Filed Pursuant to Rule 424(b)(5)
Registration No. 333-255724
Prospectus Supplement
(To Prospectus dated May 3, 2021)
3,500,000 Shares
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Common Stock
We are offering 3,500,000 shares of our common stock to be sold in the offering. Our common stock is listed on The Nasdaq Global Market under the symbol “KROS.” On January 3, 2024, the last reported sale price of our common stock as reported on The Nasdaq Global Market was $41.26 per share.
Investing in our common stock involves a high degree of risk. See “Risk Factors” on page S-10 of this prospectus supplement and in the documents incorporated by reference into this prospectus supplement before investing in our common stock.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
Per ShareTotal
Public offering price$40.00 $140,000,000 
Underwriting discounts and commissions(1)
$2.40 $8,400,000 
Proceeds, before expenses, to us$37.60 $131,600,000 
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(1)See the section titled “Underwriting” for additional information regarding underwriter compensation and estimated offering expenses.
We have granted the underwriters an option for a period of 30 days to purchase up to 525,000 additional shares of our common stock. If the underwriters exercise the option in full, the total underwriting discounts and commissions payable by us will be approximately $9.7 million, and the total proceeds to us, before expenses, will be approximately $151.3 million.
The underwriters expect to deliver the shares to purchasers on or about January 8, 2024.
Joint Book-Running Managers
Goldman Sachs & Co. LLCLeerink PartnersPiper SandlerTruist Securities
Prospectus Supplement dated January 3, 2024.



TABLE OF CONTENTS
Prospectus Supplement
Prospectus
We and the underwriters have not authorized anyone to provide you with information different than that which is contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and in any free writing prospectus that we have authorized for use in connection with this offering. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We and the underwriters are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their
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entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus supplement entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”
We are not, and the underwriters are not, making an offer to sell our common stock in any jurisdiction where the offer or sale is not permitted. We have not, and the underwriters have not, done anything that would permit this offering or possession or distribution of this prospectus supplement, the accompanying prospectus or any free writing prospectus we have authorized for use in connection with this offering in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the shares of common stock and the distribution of this prospectus outside the United States.
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ABOUT THIS PROSPECTUS SUPPLEMENT
This prospectus supplement and the accompanying prospectus is a part of an automatic registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process available to us as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act of 1933, as amended, or the Securities Act. The prospectus supplement describes the specific terms of this offering and also adds to and updates the information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The accompanying prospectus gives more general information, some of which may not apply to this offering. This prospectus supplement may add, update or change information contained in the accompanying prospectus. To the extent that any statement we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus, or any documents incorporated by reference, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus, including the documents incorporated by reference therein. Information in any document we subsequently file that is incorporated by reference shall modify or supersede the information in this prospectus supplement, the accompanying prospectus and documents incorporated by reference prior to such subsequent filing. Generally, when we refer to the prospectus, we are referring to this prospectus supplement and the accompanying prospectus combined.
We have not authorized anyone to provide you with information different than or inconsistent with the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and in any free writing prospectus that we have authorized for use in connection with this offering. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents, regardless of the time of delivery of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus supplement entitled “Where You Can Find Additional Information” and “Incorporation of Certain Information by Reference.”
We are offering to sell, and seeking offers to buy, our securities only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the accompanying prospectus and the offering of our securities in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of our securities and the distribution of this prospectus supplement and the accompanying prospectus outside the United States. This prospectus supplement and the accompanying prospectus do not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement and the accompanying prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.
Unless the context requires otherwise, references in this prospectus to the “company,” “Keros,” “we,” “us” and “our” refer to Keros Therapeutics, Inc. and its consolidated subsidiaries.
This prospectus supplement, the accompanying prospectus and the information incorporated herein and therein by reference may include trademarks, service marks and trade names owned by us or other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus supplement or the accompanying prospectus are the property of their respective owners.
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PROSPECTUS SUPPLEMENT SUMMARY
This summary highlights selected information contained elsewhere or incorporated by reference in this prospectus supplement and the accompanying prospectus. This summary does not contain all the information you should consider before investing in our common stock. You should read and consider carefully the more detailed information in this prospectus supplement and the accompanying prospectus, including the factors described under the heading “Risk Factors” in this prospectus supplement and the financial and other information incorporated by reference in this prospectus supplement and the accompanying prospectus, as well as the information included in any free writing prospectus that we have authorized for use in connection with this offering, before making an investment decision.
Company Overview
We are a clinical-stage biopharmaceutical company focused on developing and commercializing novel therapeutics to treat a wide range of patients with disorders that are linked to dysfunctional signaling of the transforming growth factor-beta, or TGF-ß, family of proteins. We are a leader in understanding the role of the TGF-ß family of proteins, which are master regulators of the growth, repair and maintenance of blood cells and a number of tissues, including bone, skeletal muscle, adipose and heart tissue. By leveraging this understanding, we have discovered and are developing large and small molecules that have the potential to provide meaningful and potentially disease-modifying benefit to patients.
Our lead protein therapeutic product candidate, KER-050 (elritercept), is an engineered ligand trap comprised of a modified ligand-binding domain of the TGF-ß superfamily receptor known as activin receptor type IIA, or ActRIIA, that is fused to the portion of the human antibody known as the Fc domain. KER-050 is being developed for the treatment of low blood cell counts, or cytopenias, including anemia and thrombocytopenia, in patients with myelodysplastic syndromes, or MDS, and in patients with myelofibrosis. In December 2023, we announced additional data from our ongoing Phase 2 clinical trial evaluating KER-050 for the treatment of anemia and thrombocytopenia in patients with very low-, low-, or intermediate-risk MDS. We expect to report additional data from Part 2 of the trial in the first half of 2024, and plan to engage with regulators on the design of the planned Phase 3 clinical trial of KER-050 in patients with MDS in the first half of 2024. Additionally, in December 2023, we announced additional data from our ongoing Phase 2 clinical trial evaluating KER-050 for the treatment of patients with myelofibrosis-associated cytopenias, which we refer to as the RESTORE trial. We expect to announce additional data from this trial in the first half of 2024.
Our second product candidate, KER-012, is designed to bind to and inhibit the signaling of TGF-ß ligands that stimulate smooth muscle hypertrophy and fibrosis, including activin A, activin B and myostatin (GDF8). We believe that KER-012 has the potential to increase the signaling of bone morphogenic protein, or BMP, pathways through this inhibition of activin A and activin B signaling, and consequently treat diseases such as pulmonary arterial hypertension, or PAH, that are associated with reduced BMP signaling, including inactivating mutations in the BMP receptors. We are developing KER-012 for the treatment of PAH and for the treatment of cardiovascular disorders, and have dosed the first patient in our Phase 2 clinical trial evaluating KER-012 in patients with PAH, which we refer to as the TROPOS trial. We expect to provide an update on enrollment for the TROPOS trial in the first half of 2024. We also expect to announce initial data from an open-label Phase 2 biomarker clinical trial of KER-012 in patients with chronic heart failure with preserved ejection fraction and in such patients with reduced ejection fraction in the second half of 2024.
Our third product candidate, KER-065, is designed to bind to and inhibit TGF-ß ligands, including myostatin (GDF8) and activin A, which are negative regulators of muscle and bone mass and strength. Through inhibition of these TGF-ß ligands, we believe that KER-065 has the potential to induce muscle and bone anabolic effects, increase fat metabolism and reduce fibrosis. We are developing KER-065 for the treatment of obesity and for the treatment of neuromuscular diseases. Significant loss of lean muscle mass has been associated with weight loss mediated by the class of glucagon-like pepetide-1, or GLP-1, receptor agonists. We believe that KER-065 has the potential to increase skeletal muscle by targeting myostatin and activin A, increase energy expenditure, reduce body fat, improve insulin resistance and improve cardiac function. Additionally, glucocorticoids, the standard of care in Duchenne muscular dystrophy, or DMD, can have significant side effects when used long-term, including
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catabolism of muscle, increased fat and accelerated bone loss. Increased body adiposity, loss of skeletal muscle and bone loss are consequences of obesity. We have initiated a Phase 1 clinical trial of KER-065 in a healthy volunteer adult population, and expect to announce initial data from this trial in the first quarter of 2025. Following the completion of this trial, we plan to initiate a proof-of-concept trial of KER-065 in obese patients.
The following table sets forth our product candidates and their current development stages.
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Recent Developments
KER-065 Update
KER-065 is a novel ligand trap comprised of a modified ligand-binding domain derived from ActRIIA and activin receptor type IIB, or ActRIIB, that is fused to the portion of the human antibody known as the Fc domain. We are developing KER-065 for the treatment of obesity and for the treatment of neuromuscular diseases.
Obesity
Obesity is a complex and chronic disease defined as having a body mass index, or BMI, of greater than or equal to 30, and is caused by abnormal or excessive fat accumulation due to an imbalance in energy intake and consumption over a long period of time. There are many comorbidities associated with obesity, including type 2 diabetes, cardiovascular disease, hypertension, heart disease, sleep apnea and some cancers, as well as an increased risk of death. According to the World Health Organization, in 2016, more than 1.9 billon adults worldwide were overweight, with 650 million considered to be obese. The prevalence of obesity has tripled since 1975 and is projected to affect one billion people globally by 2030. According to the Centers for Disease Control and Prevention, the estimated annual medical cost of obesity in the U.S. was nearly $173.0 billion in 2019 dollars.
Limitations of Current Treatment Options for Obesity
The first-line treatment for obesity is lifestyle change brought about through a combination of diet, exercise and behavior therapy. While lifestyle modifications can lead to weight loss, the magnitude required (approximately 10% to 15% of total body weight) to translate into clinical improvement for certain comorbid conditions, including obstructive sleep apnea and non-alcoholic steatotic hepatitis, is often difficult to achieve and sustain over time outside of a clinical trial setting. A third-party retrospective observational study of over 10,000 obese participants enrolled in a medically supervised weight management program demonstrated an average weight loss of 5.8% from baseline over a five-year period.
GLP-1 is a metabolic hormone, or incretin, and GLP-1 receptor agonists represent an emerging class of therapies used to achieve weight loss. Third-party clinical data with incretin-targeted therapeutics have demonstrated substantial and sustained reductions in body weight. Wegovy, a GLP-1 receptor agonist, and Zepbound, a dual GLP-1/glucose-dependent insulinotropic polypeptide receptor agonist, are both approved in the United States for the treatment of obesity.
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In a double-blind Phase 3 clinical trial of Wegovy, adults with obesity who did not have diabetes were randomly assigned, in a 2:1 ratio, to 68 weeks of treatment with once-weekly subcutaneous Wegovy (at a dose of 2.4 mg) or placebo, plus lifestyle intervention. In this trial, the mean change in body weight from baseline to week 68 was −14.9% in the Wegovy group as compared with −2.4% in the placebo group. However, based on the publicly reported data, we estimate that nearly 40% of the weight loss in a subpopulation assessed by dual energy X-ray absorptiometry (DEXA) was attributable to loss of lean mass, which could potentially lead to frailty. Accordingly, we believe there is a need for a treatment option that leads to weight loss without an associated loss of muscle and the potential for premature onset of sarcopenia.
Based on our preclinical data, we believe that KER-065 has the potential to increase skeletal muscle in obese individuals and to reduce fat mass through an increase in energy expenditure, improve insulin sensitivity and improve cardiac function. Additionally, we believe that KER-065 in combination with incretins has the potential to ameliorate muscle loss, further reduce fat mass and improve cardiac health directly.
Preclinical Data
We have generated preclinical data that we believe demonstrated proof-of-mechanism of KER-065 for the treatment of obesity with a research form of KER-065, or RKER-065, and with a research form of another ActRII ligand trap closely related to KER-065, which we refer to as RKER-034. Specifically, in preclinical studies:
KER-065 and KER-034 each showed high affinity for and potent inhibition of ligands involved in the regulation of muscle and bone homeostasis;
RKER-065 and RKER-034 had equivalent increases in skeletal muscle in the diet-induced obesity model in mice; and
A combination treatment of RKER-034 and a GLP-1 receptor agonist increased lean mass in a diet-induced obesity model in mice, as compared to the loss of lean mass observed in obese mice treated with the GLP-1 receptor agonist alone.
KER-065 targeted ligands that signal through ActRIIA and ActRIIB to increase skeletal muscle and bone in preclinical studies.
KER-065 is a modified ActRII ligand trap that contains sequences from both wild-type ActRIIB and wild-type ActRIIA. In preclinical studies, KER-065 bound to and inhibited multiple ligands that signal through these cell surface receptors, including activin A and myostatin (GDF8). These ligands are key negative regulators of muscle and bone growth. Consequently, we believe KER-065 has the potential to increase skeletal muscle and bone mass, increase fat metabolism and reduce fibrosis.
KER-034, a preclinical asset from our proprietary library of investigational ActRII ligand traps, is closely related to KER-065. Similar to KER-065, KER-034 is designed to bind to and inhibit multiple TGF-ß ligands, including activin A and myostatin (GDF8), and has increased skeletal mass and bone in preclinical studies.
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Treatment with RKER-065 increased muscle mass in the mouse model of diet-induced obesity.
In preclinical studies conducted in obese mice on a high calorie diet, twice weekly dosing for four weeks of either 10 mg/kg of RKER-065, a research form of KER-065, or 10 mg/kg of RKER-034 resulted in equivalent increases in lean mass.
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**** P value <0.0001
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Twice weekly dosing of 0.041 mg/kg of semaglutide, or sema, resulted in loss of lean mass in the sema-treated obese mice. The combination treatment of 10 mg/kg of RKER-034 and 0.041 mg/kg of sema increased lean mass, while a loss of lean mass was observed in sema-treated obese mice.
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**** P value <0.0001
Twice weekly dosing of 0.041 mg/kg of sema and twice weekly dosing of 10 mg/kg of RKER-034 led to reductions in fat gain compared to untreated obese mice. However, the combination treatment of 10 mg/kg of RKER-034 and 0.041 mg/kg of sema resulted in fat loss.
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** P value <0.01
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Additionally, once weekly dosing of 0.041 mg/kg of sema resulted in loss of muscle mass of tibialis anterior from the sema-treated obese mice. The combination treatment of 10 mg/kg of RKER-034 and 0.041 mg/kg of sema increased tibialis anterior muscle mass, at equivalent levels to KER-034 treated mice.
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ns=not significant; **** P value <0.0001
Ongoing Phase 1 Clinical Trial in Healthy Volunteers
We have initiated a randomized, double-blind, placebo-controlled, two-part Phase 1 clinical trial to evaluate single and multiple ascending doses of KER-065 in healthy volunteers. The primary objectives of this trial are to assess safety, tolerability and pharmacokinetics of KER-065. Exploratory endpoints include assessments of the pharmacodynamic effect on bone, adipose, muscle, cardiac tissue and fibrosis. To aid in the assessment of adipose tissue, volunteers will be required to have a BMI ≥ 27 to ≤ 33 kg/m2 to be enrolled in Part 2 of this trial. The trial design is summarized in the figure below.
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Phase 1 Clinical Trial Design
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Clinical Development Strategy
We expect to report initial data from this trial in the first quarter of 2025. Following the completion of this trial, we plan to initiate a proof-of-concept trial of KER-065 in obese patients.
KER-012 Update
We have initiated an open-label, exploratory Phase 2 clinical trial to evaluate KER-012 in adult patients with chronic heart failure with preserved ejection fraction, or HFpEF, or with reduced ejection fraction, or HFrEF. The primary objective of this trial is to evaluate the tolerability and safety of KER-012 administered as multiple subcutaneous doses once every four weeks in patients with chronic heart failure. In addition, this trial will explore pharmacokinetics, pharmacodynamic effects and N-terminal pro B-type natriuretic peptide, a biomarker of myocardial stress.
Initially in this trial, six patients with HFpEF will be dosed with 4.5 mg/kg of KER-012 once every four weeks for up to 24 weeks. Once all six patients have completed Study Day 29, the preliminary safety data will be reviewed by the Safety Review Committee. If the Safety Review Committee recommends that the trial proceed, six further patients with HFrEF are expected to be enrolled. These patients will also receive 4.5 mg/kg of KER-012 once every four weeks for up to 24 weeks. After the last dose of KER-012, patients will enter into a safety follow-up period for eight weeks.
We expect to announce initial data from this trial in the second half of 2024.
Corporate Information
Keros Therapeutics, Inc. was originally incorporated under the laws of the State of Delaware under the name Keros Therapeutics, Inc. in December 2015. Our principal executive office is located at 1050 Waltham Street, Suite 302, Lexington, Massachusetts 02421. Our telephone number is (617) 314-6297. Our website address is www.kerostx.com. The information contained in, or that can be accessed through, our website is not incorporated by reference herein and is not part of this prospectus supplement.
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The Offering
Common stock offered by us
3,500,000 shares of our common stock.
Common stock to be outstanding immediately after this offering
33,179,143 shares (or 33,704,143 shares if the underwriters exercise their option to purchase additional shares in full).
Option to purchase additional shares
We have granted the underwriters an option to purchase up to 525,000 additional shares of our common stock. This option is exercisable, in whole or in part, for a period of 30 days from the date of this prospectus supplement.
Use of proceeds
We intend to use the net proceeds of this offering, together with our existing cash and cash equivalents, to continue to advance the development of KER-050 in two Phase 2 clinical trials, one in patients with MDS and one in patients with myelofibrosis, and to initiate one Phase 3 clinical trial; to continue the development of KER-012 in two Phase 2 clinical trials, one in patients with PAH and one in patients with chronic heart failure with preserved ejection fraction and in such patients with reduced ejection fraction; to advance the development of KER-065, including the completion of the ongoing Phase 1 clinical trial; and to continue the development of our preclinical pipeline. We intend to use the remainder, if any, to fund other research and development activities, including activities related to our proprietary discovery approach, for working capital and for general corporate purposes. See section entitled “Use of Proceeds” on page S-13 of this prospectus supplement.
Risk factors
Investing in our common stock involves a high degree of risk. See section entitled “Risk Factors” on page S-10 of this prospectus supplement and in our Annual Report on Form 10-K for the year ended December 31, 2022, in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2023 and in the other documents which are incorporated by reference in this prospectus supplement in their entirety.
Nasdaq Global Market symbol
“KROS.”
The number of shares of our common stock to be outstanding immediately after this offering is based on 29,679,143 shares outstanding as of September 30, 2023, and excludes:
4,424,107 shares of our common stock issuable upon the exercise of options outstanding as of September 30, 2023, at a weighted-average exercise price of $35.61 per share;
1,038,414 shares of our common stock reserved for future issuance pursuant to our 2020 Equity Incentive Plan, or 2020 Plan, as of September 30, 2023, as well as any shares reserved pursuant to provisions in our 2020 Plan that automatically increase the number of shares of common stock reserved for issuance under the 2020 Plan; and
929,451 shares of our common stock reserved for issuance under our 2020 Employee Stock Purchase Plan, or the ESPP, as of September 30, 2023, as well as any shares reserved pursuant to provisions in the ESPP that automatically increase the number of shares of common stock reserved for issuance under the ESPP.
Except as otherwise indicated, all information in this prospectus supplement assumes no exercise by the underwriters of their option to purchase additional shares.
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In addition, the number of shares of our common stock to be outstanding immediately after this offering as shown above does not include the up to $141.0 million of shares issuable as of September 30, 2023 pursuant to our Sales Agreement with Leerink Partners LLC, which we refer to as the Sales Agreement. As of September 30, 2023, we have sold 5,921,311 shares of common stock at a weighted average price of $43.74 per share pursuant to the Sales Agreement.
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RISK FACTORS
Investing in our common stock involves a high degree of risk. Our business, prospects, financial condition or operating results could be materially adversely affected by the risks identified below and in the documents incorporated by reference in this prospectus supplement, as well as other risks not currently known to us or that we currently consider immaterial. The trading price of our common stock could decline due to any of these risks, and you may lose all or part of your investment. In assessing the risks described below, you should also refer to the information, including under the heading “Risk Factors,” contained in our Annual Report on Form 10-K for the year ended December 31, 2022, in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2023, and in the other documents which are incorporated by reference in this prospectus supplement in their entirety.
Risks Related to this Offering
Management will have broad discretion as to the use of the net proceeds from the shares of common stock we are selling in this offering, and we may not use these proceeds effectively.
Our management will have broad discretion in the application of the net proceeds from the shares of common stock we are selling in this offering and could spend these proceeds in ways that do not improve our results of operations or enhance the value of our common stock. Our failure to apply these funds effectively could have a material adverse effect on our business, delay the development of our product candidates, and cause the price of our common stock to decline.
If you purchase the common stock sold in this offering, you will experience immediate and substantial dilution in your investment. You will experience further dilution if we issue additional equity securities in the future.
Since the price per share of our common stock being offered is substantially higher than the net tangible book value per share of our common stock, you will suffer substantial dilution as described below. Based on the public offering price of $40.00 per share, and our pro forma as adjusted net tangible book value as of September 30, 2023, after giving effect to this offering and the sale of 2,070,679 shares of our common stock pursuant to the Sales Agreement subsequent to September 30, 2023, for net proceeds of approximately $68.5 million, if you purchase shares of common stock in this offering, you will suffer immediate and substantial dilution of $25.94 per share with respect to the pro forma as adjusted net tangible book value per share of the common stock. See the section of this prospectus supplement entitled “Dilution” for a more detailed discussion of the dilution you will incur if you purchase common stock in this offering.
In addition, we have a significant number of stock options outstanding. To the extent that outstanding stock options have been or may be exercised, investors purchasing our common stock in this offering may experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders or result in downward pressure on the price of our common stock.
A sale of a substantial number of shares of our common stock may cause the price of our common stock to decline.
Sales of a substantial number of shares of our common stock in the public market could occur at any time. If our stockholders sell, or the market perceives that our stockholders intend to sell, substantial amounts of our common stock in the public market, the market price of our common stock could decline significantly.
We cannot predict what effect, if any, sales of our shares in the public market or the availability of shares for sale will have on the market price of our common stock. However, future sales of substantial amounts of our common stock in the public market, including shares issued upon exercise of outstanding options or warrants, or the perception that such sales may occur, could adversely affect the market price of our common stock.
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In addition, Goldman Sachs & Co. LLC, Leerink Partners LLC and Piper Sandler & Co. may, in their sole discretion, release all or some portion of the shares subject to lock-up agreements at any time and for any reason. Sales of a substantial number of such shares upon expiration of the lock-up and market stand-off agreements, the perception that such sales may occur, or early release of these agreements, could cause our market price to fall or make it more difficult for you to sell your common stock at a time and price that you deem appropriate.
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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
Statements contained in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein that are not strictly historical in nature are forward-looking statements within the meaning of Section 27A of the Securities Act, and within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These forward-looking statements are subject to the “safe harbor” created by Section 27A of the Securities Act and Section 21E of the Exchange Act and may include, but are not limited to, statements related to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. All statements other than statements of historical facts contained in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein, including statements regarding our strategy, future financial condition, future operations, research and development, planned clinical trials and preclinical studies, proprietary discovery approach, the timing and likelihood of regulatory filings and approvals for our product candidates, our ability to commercialize our product candidates, the potential benefits of collaborations, projected costs, prospects, plans, objectives of management and expected market growth, are forward-looking statements.
In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “design,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “positioned,” “potential,” “predict,” “seek,” “should,” “target,” “will,” “would” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These statements reflect our views as of the date on which they were made with respect to future events and are based on assumptions and subject to risks and uncertainties. The underlying information and expectations are likely to change over time. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date the statement is made, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.
Given these uncertainties, you should not place undue reliance on these forward-looking statements as actual events or results may differ materially from those projected in the forward-looking statements due to various factors, including, but not limited to, those set forth under the heading “Risk Factors” in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein, or any free writing prospectus that we authorized. These forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements contained in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein by these cautionary statements. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. Before deciding to purchase our common stock, you should carefully consider the risk factors discussed herein or incorporated by reference, in addition to the other information set forth in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein and therein. or any free writing prospectus that we authorized.
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USE OF PROCEEDS
We estimate that the net proceeds we will receive from this offering will be approximately $131.2 million (or approximately $151.0 million if the underwriters exercise their option to purchase additional shares of our common stock in full), after deducting the underwriting discounts and commissions and estimated offering expenses payable by us.
We intend to use the net proceeds of this offering, together with our existing cash and cash equivalents, to continue to advance the development of KER-050 in two Phase 2 clinical trials, one in patients with MDS and one in patients with myelofibrosis, and to initiate one Phase 3 clinical trial; to continue the development of KER-012 in two Phase 2 clinical trials, one in patients with PAH and one in patients with chronic heart failure with preserved ejection fraction and in such patients with reduced ejection fraction; to advance the development of KER-065, including the completion of the ongoing Phase 1 clinical trial; and to continue the development of our preclinical pipeline. We intend to use the remainder, if any, to fund other research and development activities, including activities related to our proprietary discovery approach, for working capital and for general corporate purposes. We may also use a portion of the remaining net proceeds to in-license, acquire or invest in complementary businesses, technologies, products or assets. However, we have no current commitments or obligations to do so.
Based on our current operating plan, we believe that the net proceeds from this offering, together with our cash and cash equivalents as of September 30, 2023 and net proceeds of approximately $68.5 million from the sale of shares of our common stock pursuant to the Sales Agreement subsequent to September 30, 2023, will enable us to fund our planned operating expenses and capital expenditure requirements to the end of 2026. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect.
The amounts and timing of these expenditures will depend on a number of factors, such as the timing and progress of our research and development efforts, the timing and progress of any partnering efforts, and the competitive environment for our product candidates. We may temporarily invest the net proceeds in a variety of capital preservation instruments, including short-term, investment-grade, interest-bearing instruments and U.S. government securities, or may hold such proceeds as cash, until they are used for their stated purpose. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses of the net proceeds from this offering. Accordingly, we will retain broad discretion over the use of such proceeds.
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DIVIDEND POLICY
We have never declared or paid any cash dividends on our capital stock. We currently intend to retain all available funds and any future earnings to support our operations and finance the growth and development of our business. We do not intend to pay cash dividends on our common stock for the foreseeable future. Any future determination related to our dividend policy will be made at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements, contractual restrictions, business prospects and other factors our board of directors may deem relevant.
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DILUTION
Investors purchasing shares of our common stock in this offering will experience immediate and substantial dilution in the pro forma net tangible book value of their shares of common stock. Dilution in net tangible book value represents the difference between the public offering price per share and the adjusted net tangible book value per share of our common stock immediately after this offering.
The historical net tangible book value as of September 30, 2023 was $295.8 million, or $9.97 per share. Historical net tangible book value per share of our common stock represents our total tangible assets (total assets less intangible assets) less total liabilities, divided by the number of shares of common stock outstanding as of that date.
The pro forma net tangible book value as of September 30, 2023 was $364.3 million, or $11.47 per share. Pro forma net tangible book value per share of our common stock represents our total tangible assets (total assets less intangible assets) less total liabilities, divided by the number of shares of common stock outstanding as of that date, after giving effect to the sale of 2,070,679 shares of our common stock pursuant to the Sales Agreement subsequent to September 30, 2023, for net proceeds of approximately $68.5 million.
After giving effect to the issuance of 3,500,000 shares of common stock by us at the public offering price of $40.00 per share, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us, our pro forma as adjusted net tangible book value as of September 30, 2023 would have been approximately $495.6 million, or $14.06 per share of common stock. This represents an immediate increase in pro forma net tangible book value of $2.59 per share to existing stockholders and an immediate dilution of $25.94 per share to new investors purchasing our common stock in this offering.
The following table illustrates this dilution on a per share basis to new investors, assuming the underwriters do not exercise their option to purchase additional shares of our common stock:
Public offering price per share
$40.00 
Historical net tangible book value per share as of September 30, 2023
$9.97 
Pro forma increase in net tangible book value per share as of September 30, 2023 attributable to the pro forma Sales Agreement transactions described above
1.50 
Pro forma net tangible book value per share as of September 30, 2023
$11.47 
Increase in pro forma net tangible book value per share attributable to new investors purchasing shares in this offering
2.59
Pro forma as adjusted net tangible book value per share after giving effect to this offering
$14.06 
Dilution per share to new investors participating in this offering
$25.94 
If the underwriters exercise their option in full to purchase an additional 525,000 shares of common stock from us in this offering, the pro forma as adjusted net tangible book value per share after the offering would be $14.40 per share, the increase in the pro forma as adjusted net tangible book value per share to existing stockholders would be $2.93 per share and the dilution to new investors purchasing our common stock in this offering would be $25.60 per share.
The above discussion and table are based on 29,679,143 shares of common stock outstanding as of September 30, 2023, and excludes:
4,424,107 shares of our common stock issuable upon the exercise of options outstanding as of September 30, 2023, at a weighted-average exercise price of $35.61 per share;
1,038,414 shares of our common stock reserved for future issuance pursuant to our 2020 Plan as of September 30, 2023, as well as any shares reserved pursuant to provisions in our 2020 Plan that
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automatically increase the number of shares of common stock reserved for issuance under the 2020 Plan; and
929,451 shares of our common stock reserved for issuance under the ESPP as of September 30, 2023, as well as any shares reserved pursuant to provisions in the ESPP that automatically increase the number of shares of common stock reserved for issuance under the ESPP.
In addition, the number of shares of our common stock to be outstanding immediately after this offering as shown above does not include the up to $141.0 million of shares issuable as of September 30, 2023 pursuant to the Sales Agreement. As of September 30, 2023, we have sold 5,921,311 shares of common stock at a weighted average price of $43.74 per share pursuant to the Sales Agreement.
In addition, we may choose to raise additional capital due to market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. To the extent that we raise additional capital by issuing equity securities or convertible debt, your ownership will be further diluted.
To the extent that existing options are exercised, new options are issued under our 2020 Plan or shares of common stock are issued under our ESPP in the future, there will be further dilution to investors participating in this offering.
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UNDERWRITING
Subject to the terms and conditions set forth in the underwriting agreement, dated January 3, 2024, among us and Goldman Sachs & Co. LLC, Leerink Partners LLC, Piper Sandler & Co. and Truist Securities, Inc., as the representatives of the underwriters named below and the joint book-running managers of this offering, we have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase from us, the respective number of shares of common stock shown opposite its name below:
Underwriter
Number of Shares
Goldman Sachs & Co. LLC
1,365,000
Leerink Partners LLC
1,102,500
Piper Sandler & Co.
787,500
Truist Securities, Inc.
245,000
Total
3,500,000
The underwriting agreement provides that the obligations of the several underwriters are subject to certain conditions precedent such as the receipt by the underwriters of officers’ certificates and legal opinions and approval of certain legal matters by their counsel. The underwriting agreement provides that the underwriters will purchase all of the shares of common stock if any of them are purchased. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the nondefaulting underwriters may be increased or the underwriting agreement may be terminated. We have agreed to indemnify the underwriters and certain of their controlling persons against certain liabilities, including liabilities under the Securities Act, and to contribute to payments that the underwriters may be required to make in respect of those liabilities.
The underwriters have advised us that, following the completion of this offering, they currently intend to make a market in the common stock as permitted by applicable laws and regulations. However, the underwriters are not obligated to do so, and the underwriters may discontinue any market-making activities at any time without notice in their sole discretion. Accordingly, no assurance can be given as to the liquidity of the trading market for the common stock, that you will be able to sell any of the common stock held by you at a particular time or that the prices that you receive when you sell will be favorable.
The underwriters are offering the shares of common stock subject to prior sale, when, as and if issued to and accepted by them, subject to approval of legal matters by their counsel, including the validity of the shares of common stock. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.
Commission and Expenses
The underwriters have advised us that they propose to offer the shares of common stock to the public at the public offering price set forth on the cover page of this prospectus supplement and to certain dealers, which may include the underwriters, at that price less a concession not in excess of $1.44 per share of common stock. The underwriters may allow, and certain dealers may reallow, a discount from the concession not in excess of $0.48 per share of common stock to certain brokers and dealers. After the offering, the public offering price, concession and reallowance to dealers may be reduced by the representatives. No such reduction will change the amount of proceeds to be received by us as set forth on the cover page of this prospectus supplement.
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The following table shows the public offering price, the underwriting discounts and commissions that we are to pay the underwriters and the proceeds, before expenses, to us in connection with this offering. Such amounts are shown assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares.
Per Share
Total
Without Option to Purchase Additional Shares
With Option to Purchase Additional Shares
Without Option to Purchase Additional Shares
With Option to Purchase Additional Shares
Public offering price
$40.00 $40.00 $140,000,000 $161,000,000 
Underwriting discounts and commissions paid by us
$2.40 $2.40 $8,400,000 $9,660,000 
Proceeds to us, before expenses
$37.60 $37.60 $131,600,000 $151,340,000 
We estimate expenses payable by us in connection with this offering, other than the underwriting discounts and commissions referred to above, will be approximately $375,000. We have agreed to reimburse the underwriters for certain of their expenses incurred in connection with this offering in an amount not to exceed $25,000.
Listing
Our common stock is listed on The Nasdaq Global Market under the trading symbol “KROS.”
Stamp Taxes
If you purchase shares of common stock offered in this prospectus supplement, you may be required to pay stamp taxes and other charges under the laws and practices of the country of purchase, in addition to the offering price listed on the cover page of this prospectus supplement.
Option to Purchase Additional Shares
We have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase, from time to time, in whole or in part, up to an aggregate of 525,000 shares from us at the public offering price set forth on the cover page of this prospectus supplement, less underwriting discounts and commissions. If the underwriters exercise this option, each underwriter will be obligated, subject to specified conditions, to purchase a number of additional shares proportionate to that underwriter’s initial purchase commitment as indicated in the table above.
No Sales of Similar Securities
We, our executive officers, directors and certain affiliates have agreed, subject to specified exceptions, not to directly or indirectly:
sell, offer, contract or grant any option to sell (including any short sale), pledge, transfer, establish an open “put equivalent position” within the meaning of Rule 16a-l(h) under the Exchange Act;
otherwise dispose of any shares of common stock, options or warrants to acquire shares of common stock, or securities exchangeable or exercisable for or convertible into shares of common stock currently or hereafter owned either of record or beneficially; or
publicly announce an intention to do any of the foregoing for a period of 90 days after the date of this prospectus supplement without the prior written consent of Goldman Sachs & Co. LLC, Leerink Partners LLC and Piper Sandler & Co.
This restriction terminates after the close of trading of the common stock on and including the 90th day after the date of this prospectus supplement.
Goldman Sachs & Co. LLC, Leerink Partners LLC and Piper Sandler & Co. may, in their sole discretion and at any time or from time to time before the termination of the 90-day period, release all or any portion of the securities subject to lock-up agreements. There are no existing agreements between the underwriters and any of our
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shareholders who will execute a lock-up agreement, providing consent to the sale of shares prior to the expiration of the lock-up period.
Stabilization
The underwriters have advised us that, pursuant to Regulation M under the Exchange Act, certain persons participating in the offering may engage in short sale transactions, stabilizing transactions, syndicate covering transactions or the imposition of penalty bids in connection with this offering. These activities may have the effect of stabilizing or maintaining the market price of the common stock at a level above that which might otherwise prevail in the open market. Establishing short sales positions may involve either “covered” short sales or “naked” short sales.
“Covered” short sales are sales made in an amount not greater than the underwriters’ option to purchase additional shares of our common stock in this offering. The underwriters may close out any covered short position by either exercising their option to purchase additional shares of our common stock or purchasing shares of our common stock in the open market. In determining the source of shares to close out the covered short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option to purchase additional shares.
“Naked” short sales are sales in excess of the option to purchase additional shares of our common stock. The underwriters must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the shares of our common stock in the open market after pricing that could adversely affect investors who purchase in this offering.
A stabilizing bid is a bid for the purchase of shares of common stock on behalf of the underwriters for the purpose of fixing or maintaining the price of the common stock. A syndicate covering transaction is the bid for or the purchase of shares of common stock on behalf of the underwriters to reduce a short position incurred by the underwriters in connection with the offering. Similar to other purchase transactions, the underwriter’s purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. A penalty bid is an arrangement permitting the underwriters to reclaim the selling concession otherwise accruing to a syndicate member in connection with the offering if the common stock originally sold by such syndicate member are purchased in a syndicate covering transaction and therefore have not been effectively placed by such syndicate member.
Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. The underwriters are not obligated to engage in these activities and, if commenced, any of the activities may be discontinued at any time.
The underwriters may also engage in passive market making transactions in our common stock on The Nasdaq Global Market in accordance with Rule 103 of Regulation M during a period before the commencement of offers or sales of shares of our common stock in this offering and extending through the completion of distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded.
Electronic Distribution
A prospectus supplement and accompanying prospectus in electronic format may be made available by e-mail or on the web sites or through online services maintained by one or more of the underwriters or their affiliates. In those cases, prospective investors may view offering terms online and may be allowed to place orders online. The underwriters may agree with us to allocate a specific number of shares of common stock for sale to online brokerage account holders. Any such allocation for online distributions will be made by the underwriters on the same basis as other allocations. Other than this prospectus supplement and the accompanying prospectus in electronic format, the information on the underwriters’ web sites and any information contained in any other web site maintained by any of
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the underwriters is not part of this prospectus supplement and the accompanying prospectus, has not been approved and/or endorsed by us or the underwriters and should not be relied upon by investors.
Other Activities and Relationships
The underwriters and certain of their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. The underwriters and certain of their respective affiliates have, from time to time, performed, and may in the future perform, various commercial and investment banking and financial advisory services for us and our affiliates, for which they received or will receive customary fees and expenses.
In the ordinary course of their various business activities, the underwriters and certain of their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investment and securities activities may involve securities and/or instruments issued by us and our affiliates. If the underwriters or certain of their respective affiliates have a lending relationship with us, they routinely hedge their credit exposure to us consistent with their respective customary risk management policies. The underwriters and certain of their respective affiliates may hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities or the securities of our affiliates, including potentially the common stock offered hereby. Any such short positions could adversely affect future trading prices of the common stock offered hereby. The underwriters and certain of their respective affiliates may also communicate independent investment recommendations, market color or trading ideas and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.
Leerink Partners LLC is the sales agent under an "at the market offering" sales program ("ATM Program") under which we may offer and sell our common stock having aggregate sales proceeds of up to $400.0 million from time to time. We may not make sales of common stock under the ATM Program during the period of 90 days after the date of this prospectus supplement, in accordance with the lock-up restrictions described above.
Selling Restrictions
Notice to Prospective Investors in the EEA
In relation to each Member State of the EEA and the United Kingdom, each, a Relevant State, no offer of the shares may be made to the public in that Relevant State prior to the publication of a prospectus in relation to the shares which has been approved by the competent authority in that Relevant State or, where appropriate, approved in another Relevant State and notified to the competent authority in that Relevant State, all in accordance with the Prospectus Regulation, except that offers of shares may be made to the public in that Relevant State at any time under the following exemptions under the Prospectus Regulation:
to any legal entity which is a “qualified investor” as defined in the Prospectus Regulation;
to fewer than 150 natural or legal persons (other than qualified investors as defined in the Prospectus Regulation), subject to obtaining the prior consent of the representatives; or
in any other circumstances falling within Article 1(4) of the Prospectus Regulation,
provided that no such offer of ordinary shares referred to above shall result in a requirement for the Company or any representative to publish a prospectus pursuant to Article 3 of the Prospectus Regulation, or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation.
Each person in a Relevant State who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged, and agreed to and with the Company and the underwriters that it is a qualified investor within the meaning of the Prospectus Regulation.
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In the case of any shares being offered to a financial intermediary as that term is used in Article 5(1) of the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged, and agreed that the shares acquired by it in the offer have not been acquired on a nondiscretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer to the public other than their offer or resale in a Relevant State to qualified investors, in circumstances in which the prior consent of the underwriters has been obtained to each such proposed offer or resale.
The Company, the underwriters and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements, and agreements.
For the purposes of this provision, the expression an “offer to the public” in relation to any shares in any Relevant State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression “Prospectus Regulation” means Regulation (EU) 2017/1129.
References to the Prospectus Regulation includes, in relation to the United Kingdom, the Prospectus Regulation as it forms part of U.K. domestic law by virtue of the European Union (Withdrawal) Act 2018.
The above selling restriction is in addition to any other selling restrictions set out below.
Notice to Prospective Investors in the United Kingdom
This document is for distribution only to persons who (i) have professional experience in matters relating to investments and who qualify as investment professionals within the meaning of Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended, or the Financial Promotion Order; (ii) are persons falling within Article 49(2)(a) to (d) (“high net worth companies, unincorporated associations etc.”) of the Financial Promotion Order; (iii) are outside the United Kingdom; or (iv) are persons to whom an invitation or inducement to engage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act 2000, as amended) in connection with the issue or sale of any securities may otherwise lawfully be communicated or caused to be communicated (all such persons together being referred to as “relevant persons”). This document is directed only at relevant persons and must not be acted on or relied on by persons who are not relevant persons. Any investment or investment activity to which this document relates is available only to relevant persons and will be engaged in only with relevant persons.
Notice to Prospective Investors in Bermuda
Securities may be offered or sold in Bermuda only in compliance with the provisions of the Investment Business Act of 2003 of Bermuda which regulates the sale of securities in Bermuda. Additionally, non-Bermudian persons (including companies) may not carry on or engage in any trade or business in Bermuda unless such persons are permitted to do so under applicable Bermuda legislation.
Notice to Prospective Investors in Australia
No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission, or the ASIC, in relation to this offering. This prospectus does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001, or the Corporations Act, and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.
Any offer in Australia of the shares may only be made to persons, or the Exempt Investors, who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares without disclosure to investors under Chapter 6D of the Corporations Act.
The shares applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under this offering, except in circumstances where disclosure to investors
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under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares must observe such Australian on-sale restrictions.
This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.
Notice to Prospective Investors in Hong Kong
The shares have not been will not be offered or sold in Hong Kong by means of any document other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made thereunder or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies (Winding Up and Miscellaneous Provisions) Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the shares has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance of Hong Kong and any rules made under that Ordinance.
Notice to Prospective Investors in Japan
The shares have not been and will not be registered pursuant to Article 4, Paragraph 1 of the Financial Instruments and Exchange Act. Accordingly, neither the shares nor any interest therein may be offered or sold, directly or indirectly, in Japan or to, or for the benefit of, any “resident” of Japan (which term as used herein means any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan or to or for the benefit of a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the Financial Instruments and Exchange Act and any other applicable laws, regulations and ministerial guidelines of Japan in effect at the relevant time.
Notice to Prospective Investors in Singapore
This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of shares may not be circulated or distributed, nor may shares be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore, or the SFA, (ii) to a relevant person pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA and in accordance with the conditions specified in Section 275 of the SFA or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.
Where shares are subscribed or purchased under Section 275 of the SFA by a relevant person which is:
a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or
a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor,
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securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares pursuant to an offer made under Section 275 of the SFA except:
to an institutional investor or to a relevant person defined in Section 275(2) of the SFA, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA;
where no consideration is or will be given for the transfer;
where the transfer is by operation of law;
as specified in Section 276(7) of the SFA; or
as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations 2005 of Singapore.
Notice to Prospective Investors in Switzerland
The shares may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange, or SIX, or on any other stock exchange or regulated trading facility in Switzerland. This prospectus supplement has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this prospectus supplement nor any other offering or marketing material relating to the shares or the offering may be publicly distributed or otherwise made publicly available in Switzerland.
Neither this prospectus supplement nor any other offering or marketing material relating to the offering, the Company or the shares have been or will be filed with or approved by any Swiss regulatory authority. In particular, this prospectus supplement will not be filed with, and the offer of shares will not be supervised by, the Swiss Financial Market Supervisory Authority, and the offer of shares has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes, or CISA. The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of shares.
Notice to Prospective Investors in Canada
The shares may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors (as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario)), and are permitted clients (as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations). Any resale of the shares must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.
Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment hereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.
Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.
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LEGAL MATTERS
The validity of the shares of common stock being offered by this prospectus will be passed upon for us by Cooley LLP, Boston, Massachusetts. As of the date of this prospectus supplement, an entity comprised of partners and associates of Cooley LLP beneficially own an aggregate of 3,722 shares of our common stock. Certain legal matters in connection with the offering will be passed upon on behalf of the underwriters by Latham & Watkins LLP.
EXPERTS
The financial statements of Keros Therapeutics, Inc. incorporated in this prospectus by reference, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report. Such financial statements are incorporated by reference in reliance upon the report of such firm, given upon their authority as experts in accounting and auditing.
WHERE YOU CAN FIND MORE INFORMATION
This prospectus supplement and the accompanying prospectus are part of the registration statement on Form S-3 we filed with the SEC under the Securities Act and do not contain all the information set forth in the registration statement. Whenever a reference is made in this prospectus supplement or the accompanying prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference in this prospectus supplement and the accompanying prospectus for a copy of such contract, agreement or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov. We maintain a website at www.kerostx.com. The information contained in, or that can be accessed through, our website is not incorporated by reference herein and is not part of this prospectus.
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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
The SEC allows us to “incorporate by reference” the information we file with it, which means that we can disclose important information to you by referring you to those documents. Information incorporated by reference is part of this prospectus supplement and the accompanying prospectus. Later information filed with the SEC will update and supersede this information.
We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement until the termination of the offering of the shares covered by this prospectus supplement (other than any information furnished under Item 2.02 or Item 7.01 of any current report on Form 8-K and exhibits filed on such form that are related to such items):
our Annual Report on Form 10-K for the year ended December 31, 2022, filed with the SEC on March 3, 2023;
the portions of our Definitive Proxy Statement on Schedule 14A for our 2023 Annual Meeting of Stockholders, filed with the SEC on April 24, 2023, specifically incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2022;
our Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2023, filed with the SEC on May 4, 2023;
our Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2023, filed with the SEC on August 7, 2023;
our Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2023, filed with the SEC on November 6, 2023;
our Current Reports on Form 8-K (other than information furnished rather than filed) filed with the SEC on January 6, 2023, April 19, 2023, May 22, 2023, June 6, 2023, June 9, 2023, July 24, 2023, August 7, 2023, October 4, 2023, December 11, 2023, and January 3, 2024; and
the description of our common stock contained in our registration statement on Form 8-A filed with the SEC on April 3, 2020, including any amendments or reports filed for the purposes of updating this description, including Exhibit 4.3 to our Annual Report on Form 10-K for the year ended December 31, 2022.
We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits which are specifically incorporated by reference into such documents. You should direct any requests for documents to Keros Therapeutics, Inc., Attn: Investor Relations, 1050 Waltham Street, Suite 302, Lexington, Massachusetts 02421.
Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus.
In accordance with Rule 412 of the Securities Act, any statement contained in a document incorporated by reference herein shall be deemed modified or superseded to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement.
S-25



PROSPECTUS
keroslogo1a.jpg
Common Stock
Preferred Stock
Debt Securities
Warrants
From time to time, we may offer and sell any combination of shares of our common stock, shares of our preferred stock, debt securities and warrants to purchase any of such securities in one or more offerings as described in this prospectus. We may also offer securities as may be issuable upon conversion, redemption, repurchase, exchange or exercise of any securities registered hereunder, including any applicable antidilution provisions.
This prospectus provides a general description of the securities we may offer. Each time we offer securities, we will specify in an accompanying prospectus supplement the terms of the securities being offered. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before you invest in any of the securities being offered.
This prospectus may not be used to consummate a sale of any securities unless accompanied by a prospectus supplement.
Our common stock is traded on the Nasdaq Global Market under the symbol “KROS.” On April 30, 2021, the last reported sale price of our common stock was $58.80 per share. The applicable prospectus supplement will contain information, where applicable, as to any other listing on the Nasdaq Global Market or any securities market or other exchange of the securities, if any, covered by the prospectus supplement. We are an “emerging growth company” as defined under the federal securities laws and, as such, have elected to comply with certain reduced public company reporting requirements and may continue to so elect for future filings.
These securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section titled “Plan of Distribution” in this prospectus. If any agents, underwriters or dealers are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such agents, underwriters or dealers and any applicable fees, commissions, discounts or over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.
Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” on page 5 of this prospectus and contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
The date of this prospectus is May 3, 2021.



TABLE OF CONTENTS
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ABOUT THIS PROSPECTUS
This prospectus is a part of an automatic registration statement on Form S-3 that we filed with the U.S. Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process available to us as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act of 1933, as amended, or the Securities Act. Under this shelf registration process, we may offer and sell from time to time in one or more offerings the securities described in this prospectus. No limit exists on the aggregate number or amount of securities we may sell pursuant to the registration statement of which this prospectus is a part.
This prospectus provides you with a general description of the securities we may offer. Each time we offer securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of these securities and offerings. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in any documents that we have incorporated by reference into this prospectus. We urge you to read carefully this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the heading “Incorporation of Certain Information by Reference,” before investing in any of the securities offered.
THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.
Neither we, nor any agent, underwriter or dealer has authorized any person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus, any applicable prospectus supplement or any related free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus, any applicable supplement to this prospectus or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.
You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date.
This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find More Information.”
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PROSPECTUS SUMMARY
This summary highlights selected information contained elsewhere in this prospectus or incorporated by reference in this prospectus, and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities discussed under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements and the related notes thereto, and the exhibits to the registration statement of which this prospectus is a part.
Unless the context requires otherwise, references in this prospectus to the “company,” “Keros,” “we,” “us” and “our” refer to Keros Therapeutics, Inc. and its consolidated subsidiaries.
Company Overview
We are a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of novel treatments for patients suffering from hematological and musculoskeletal disorders with high unmet medical need. We are a leader in understanding the role of the Transforming Growth Factor-Beta, or TGF-ß, family of proteins, which are master regulators of red blood cell and platelet production as well as of the growth, repair and maintenance of muscle and bone. We have leveraged this understanding and developed a discovery approach to generate large and small molecules to address diseases of these tissues. Targeting TGF-ß signaling pathways has been clinically proven to elicit robust changes in blood cells, muscle and bone, which we believe provides a precedent and strong rationale for our strategy. Our lead protein therapeutic product candidate, KER-050, is being developed for the treatment of low blood cell counts, or cytopenias, including anemia and thrombocytopenia, in patients with myelodysplastic syndromes and in patients with myelofibrosis. Our lead small molecule product candidate, KER-047, is being developed for the treatment of anemia resulting from iron imbalance, as well as for the treatment of fibrodysplasia ossificans progressiva, a rare musculoskeletal disorder. Our third product candidate, KER-012, is being developed for the treatment of disorders associated with bone loss, such as osteoporosis and osteogenesis imperfecta, and for the treatment of pulmonary arterial hypertension. We believe KER-047 and KER-012 offer substantial opportunities for us to continue to apply our understanding of TGF-ß signaling pathways and expand our development programs in related hematological and musculoskeletal disorders with high unmet medical need.
Corporate Information
Keros Therapeutics, Inc. was originally incorporated under the laws of the State of Delaware under the name Keros Therapeutics, Inc. in December 2015. Our principal executive office is located at 99 Hayden Avenue, Suite 120, Building E, Lexington, Massachusetts 02421. Our telephone number is (617) 314-6297. Our website address is www.kerostx.com. The information contained in, or that can be accessed through, our website is not incorporated by reference herein and is not part of this prospectus.
We use various trademarks and trade names in our business, including without limitation our corporate name and logo. All other trademarks or trade names referred to in this prospectus are the property of their respective owners. This prospectus, any applicable prospectus supplement and the information incorporated herein or therein by reference may also contain trademarks and trade names of third parties, which are the property of their respective owners. Solely for convenience, the trademarks and trade names referred to or incorporated by reference in this prospectus, any applicable prospectus supplement or any free writing prospectus may be referred to without the ® and TM symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.
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Implications of Being an Emerging Growth Company
We qualify as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. As an emerging growth company, we may take advantage of specified reduced disclosure and other requirements that are otherwise applicable generally to public companies. These provisions include:
being permitted to present in this prospectus only two years of audited financial statements, with correspondingly reduced “Management’s Discussion and Analysis of Financial Condition and Results of Operations” disclosure;
reduced disclosure about the compensation paid to our executive officers;
not being required to submit to our stockholders advisory votes on executive compensation or golden parachute arrangements;
an exemption from the auditor attestation requirement in the assessment of our internal control over financial reporting pursuant to the Sarbanes-Oxley Act of 2002, or the Sarbanes-Oxley Act; and
an exemption from new or revised financial accounting standards until they would apply to private companies and from compliance with any new requirements adopted by the Public Company Accounting Oversight Board requiring mandatory audit firm rotation.
We may take advantage of these exemptions until December 31, 2025 or such earlier time that we are no longer an emerging growth company. We would cease to be an emerging growth company on the date that is the earliest of (1) the last day of the fiscal year in which we have total annual gross revenues of $1.07 billion or more; (2) December 31, 2025; (3) the date on which we have issued more than $1.0 billion in nonconvertible debt during the previous three years; or (4) the date on which we are deemed to be a large accelerated filer under the rules of the Securities and Exchange Commission, or the SEC. We may choose to take advantage of some but not all of these exemptions. We have taken advantage of certain reduced reporting requirements in this prospectus. Accordingly, the information contained herein may be different from the information you receive from other public companies in which you hold stock.
We have elected to take advantage of the extended transition period to comply with new or revised accounting standards and to adopt certain of the reduced disclosure requirements available to emerging growth companies. As a result of the accounting standards election, we will not be subject to the same implementation timing for new or revised accounting standards as other public companies that are not emerging growth companies which may make comparison of our financials to those of other public companies more difficult. As a result of these elections, the information that we provide in this prospectus may be different than the information you may receive from other public companies in which you hold equity interests. In addition, it is possible that some investors will find our common stock less attractive as a result of these elections, which may result in a less active trading market for our common stock and higher volatility in our stock price.
Description of Securities
We may offer shares of our common stock, shares of our preferred stock, debt securities and warrants to purchase any of such securities, either individually or in combination with other securities, from time to time in one or more offerings under this prospectus, together with any applicable prospectus supplement and any related free writing prospectus, at prices and on terms to be determined by market conditions at the time of the relevant offering. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:
designation or classification;
aggregate principal amount or aggregate offering price;
maturity date, if applicable;
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original issue discount, if any;
rates and times of payment of interest or dividends, if any;
redemption, conversion, exchange or sinking fund terms, if any;
conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;
ranking, if applicable;
restrictive covenants, if any;
voting or other rights, if any; and
material or special U.S. federal income tax considerations, if any.
The applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.
This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.
We may sell the securities directly to investors or through underwriters, dealers or agents. We, and our underwriters or agents, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities through underwriters or agents, we will include in the applicable prospectus supplement:
the names of those underwriters or agents;
applicable fees, discounts and commissions to be paid to them;
details regarding over-allotment or other options, if any; and
the estimated net proceeds to us.
Common Stock. We may issue shares of our common stock from time to time. Each holder of our common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Subject to any preferential rights of any then outstanding shares of preferred stock, in the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in the net assets remaining after payment of all of our debts and other liabilities and the liquidation preferences of any then outstanding shares of preferred stock. Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. In this prospectus, we have summarized certain general features of the common stock under the heading “Description of Capital Stock—Common Stock.” We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to any common stock being offered.
Preferred Stock. We may issue shares of our preferred stock from time to time, in one or more series. Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by stockholders, to designate up to 10,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges, qualifications and restrictions granted to or imposed upon the preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preference and sinking fund terms, any or all of which may be greater than the rights of the common stock. To date, none of the 10,000,000 authorized shares of preferred stock have been designated by our board of directors. Convertible preferred stock will be
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convertible into our common stock or exchangeable for our other securities. Conversion may be mandatory or at the option of the holders of our preferred stock and would be at prescribed conversion rates.
If we sell any series of preferred stock under this prospectus as supplemented by a prospectus supplement and, if applicable, a free writing prospectus, we will fix the designations, voting powers, preferences and rights of the preferred stock of each such series, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that contains the terms of the series of preferred stock we are offering. In this prospectus, we have summarized certain general features of the preferred stock under “Description of Capital Stock—Preferred Stock.” We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.
Debt Securities. We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible or exchangeable debt securities will be convertible into or exchangeable for our common stock or preferred stock. Conversion or exchange may be mandatory or optional (at our option or the holders’ option) and would be at prescribed conversion rates or exchange prices.
The debt securities will be issued under one or more documents called indentures, which are contracts between us and a national banking association or other eligible party, as trustee. In this prospectus, we have summarized certain general features of the debt securities under the heading “Description of Debt Securities.” We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the series of debt securities being offered, as well as the complete indenture and any supplemental indentures that contain the terms of the debt securities. A form of indenture has been filed as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.
Warrants. We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. In this prospectus, we have summarized certain general features of the warrants under the heading “Description of Warrants.” We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the form of warrant and/or the warrant agreement and warrant certificate, as applicable, that contain the terms of the warrants. We have filed the forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants that we may offer as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant and/or the warrant agreement and warrant certificate, as applicable, that contain the terms of the particular series of warrants we are offering, and any supplemental agreements, before the issuance of such warrants.
Warrants may be issued under a warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if any, in the applicable prospectus supplement relating to a particular series of warrants.
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RISK FACTORS
Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and described under the section titled “Risk Factors” contained in our most recent Annual Report on Form 10-K as well as any amendments thereto reflected in subsequent filings with the SEC, which are incorporated by reference into this prospectus in their entirety, together with other information in this prospectus, the documents incorporated by reference and any free writing prospectus that we may authorize for use in connection with a specific offering. See “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.” The risks described in these documents are not the only ones we face, but those that we consider to be material. There may be other unknown or unpredictable economic, business, competitive, regulatory or other factors that could have material adverse effects on our future results. Past financial performance may not be a reliable indicator of future performance, and historical trends should not be used to anticipate results or trends in future periods. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could be seriously harmed. This could cause the trading price of our securities to decline, resulting in a loss of all or part of your investment. Please also carefully read the section below titled “Special Note Regarding Forward-Looking Statements.”
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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
Statements contained in this prospectus, the applicable prospectus supplement and in the documents incorporated by reference herein and therein that are not strictly historical in nature are forward-looking statements within the meaning of Section 27A of the Securities Act, and within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These forward-looking statements are subject to the “safe harbor” created by Section 27A of the Securities Act and Section 21E of the Exchange Act and may include, but are not limited to, statements related to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. All statements other than statements of historical facts contained in this prospectus or in the documents incorporated by reference herein and in any prospectus supplement, including statements regarding our strategy, future financial condition, future operations, research and development, planned clinical trials and preclinical studies, technology platforms, the timing and likelihood of regulatory filings and approvals for our product candidates, our ability to commercialize our product candidates, the potential benefits of collaborations, projected costs, prospects, plans, objectives of management and expected market growth, are forward-looking statements.
In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “design,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “positioned,” “potential,” “predict,” “seek,” “should,” “target,” “will,” “would” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These statements reflect our views as of the date on which they were made with respect to future events and are based on assumptions and subject to risks and uncertainties. The underlying information and expectations are likely to change over time. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date the statement is made, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.
Given these uncertainties, you should not place undue reliance on these forward-looking statements as actual events or results may differ materially from those projected in the forward-looking statements due to various factors, including, but not limited to, those set forth under the heading “Risk Factors” in any applicable prospectus supplement, the documents incorporated by reference therein or any free writing prospectus that we authorized. These forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements contained in this prospectus, in the documents incorporated by reference herein and in any prospectus supplement by these cautionary statements. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. Before deciding to purchase our securities, you should carefully consider the risk factors discussed herein or incorporated by reference, in addition to the other information set forth in this prospectus, any accompanying prospectus supplement or free writing prospectus and in the documents incorporated by reference.
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USE OF PROCEEDS
Except as described in any applicable prospectus supplement or in any related free writing prospectus that we may authorize to be provided to you, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for our operations and other general corporate purposes including, but not limited to, repayment or refinancing of indebtedness or other corporate borrowing, repurchases and redemption of our securities, working capital, intellectual property protection and enforcement, capital expenditures, and general corporate purposes, including clinical trial expenses, research and development expenses, general and administrative expenses and capital expenditures. We may also use a portion of the net proceeds to in-license, invest in or acquire businesses, assets or technologies that we believe are complementary to our own, although we have no current plans, commitments or agreements with respect to any acquisitions. As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds from the sale of the securities offered by us hereunder. Accordingly, we will retain broad discretion in the timing and application of these proceeds.
Pending application of the net proceeds as described above, we intend to invest the net proceeds in a variety of capital preservation instruments, including short-term, investment-grade, interest-bearing instruments and U.S. government securities.
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DESCRIPTION OF CAPITAL STOCK
The following description of our capital stock is based upon our amended and restated certificate of incorporation and our amended and restated bylaws. This summary does not purport to be complete and is subject to, and is qualified in its entirety by express reference to, the applicable provisions of our amended and restated certificate of incorporation and our amended and restated bylaws, which are filed as exhibits to the registration statement of which this prospectus is part. We encourage you to read our amended and restated certificate of incorporation, our amended and restated bylaws and the applicable provisions of the Delaware General Corporation Law, or the DGCL, for more information.
General
Our amended and restated certificate of incorporation authorizes us to issue up to 200,000,000 shares of common stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share, all of which shares of preferred stock are undesignated. Our board of directors may establish the rights and preferences of the preferred stock from time to time.
Common Stock
Voting Rights
Each holder of our common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Under our amended and restated certificate of incorporation and amended and restated bylaws, our stockholders will not have cumulative voting rights. Because of this, the holders of a majority of the shares of common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they should so choose.
Dividends
Subject to preferences that may be applicable to any then-outstanding preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by the board of directors out of legally available funds.
Liquidation
In the event of our liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of our debts and other liabilities and the satisfaction of any liquidation preference granted to the holders of any then-outstanding shares of preferred stock.
Rights and Preferences
Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that we may designate in the future.
Preferred Stock
Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.
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We will fix the designations, voting powers, preferences and rights of the preferred stock of each series we issue under this prospectus, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that contains the terms of the series of preferred stock we are offering. We will describe in the applicable prospectus supplement the terms of the series of preferred stock being offered, including, to the extent applicable:
the title and stated value;
the number of shares we are offering;
the liquidation preference per share;
the purchase price per share;
the dividend rate per share, dividend period, payment date or dates and method of calculation for dividends;
whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;
our right, if any, to defer payment of dividends and the maximum length of any such deferral period;
the procedures for any auction and remarketing, if any;
the provisions for a sinking fund, if any;
the provisions for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights;
any listing of the preferred stock on any securities exchange or market;
whether the preferred stock will be convertible into our common stock or other securities of ours, including warrants, and, if applicable, the conversion period, the conversion price, or how it will be calculated, and under what circumstances and the mechanism by which it may be adjusted;
whether the preferred stock will be exchangeable into debt securities or other securities of ours, and, if applicable, the exchange price, or how it will be calculated, and under what circumstances it may be adjusted, and the exchange period;
voting rights, if any;
preemptive rights, if any;
restrictions on transfer, sale or other assignment, if any;
whether interests in the preferred stock will be represented by depositary shares;
a discussion of any material or special U.S. federal income tax considerations applicable to the preferred stock;
the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;
any limitations on issuances of any class or series of preferred stock ranking senior to or on parity with the series of preferred stock being issued as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and
any other specific terms, rights, preferences, privileges, qualifications or limitations of, or restrictions on the preferred stock.
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If we issue shares of preferred stock under this prospectus, the shares will be fully-paid and non-assessable.
Unless we specify otherwise in the applicable prospectus supplement, the preferred stock will rank, with respect to dividends and upon our liquidation, dissolution or winding up:
senior to all classes or series of our common stock and to all of our equity securities ranking junior to the preferred stock;
on a parity with all of our equity securities the terms of which specifically provide that the equity securities rank on a parity with the preferred stock; and
junior to all of our equity securities the terms of which specifically provide that the equity securities rank senior to the preferred stock.
The term “equity securities” does not include convertible debt securities.
The DGCL provides that the holders of preferred stock will have the right to vote separately as a class (or, in some cases, as a series) on an amendment to our certificate of incorporation if the amendment would change the par value or, unless the certificate of incorporation provided otherwise, the number of authorized shares of the class or change the powers, preferences or special rights of the class or series so as to adversely affect the class or series, as the case may be. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.
Our board of directors may authorize the issuance of preferred stock with voting or conversion rights that could adversely affect the voting power or other rights of the holders of the common stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring or preventing a change in our control that may otherwise benefit holders of our common stock and may adversely affect the market price of the common stock and the voting and other rights of the holders of common stock. We have no current plans to issue any shares of preferred stock.
Anti-Takeover Provisions of Delaware Law and Our Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws
Section 203 of the Delaware General Corporation Law
We are subject to Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:
before such date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder;
upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction began, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the interested stockholder) those shares owned (i) by persons who are directors and also officers and (ii) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or
on or after such date, the business combination is approved by the board of directors and authorized at an annual or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock that is not owned by the interested stockholder.
Section 203 defines a “business combination” to include the following:
any merger or consolidation involving the corporation and the interested stockholder;
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any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the interested stockholder;
subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;
any transaction involving the corporation that has the effect of increasing the proportionate share of the stock or any class or series of the corporation beneficially owned by the interested stockholder; and
the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits by or through the corporation.
In general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.
The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price.
Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws
Our amended and restated certificate of incorporation provides for our board of directors to be divided into three classes with staggered three-year terms. Only one class of directors is elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms. Because our stockholders do not have cumulative voting rights, our stockholders holding a majority of the voting power of our shares of common stock outstanding will be able to elect all of our directors. The directors may be removed by the stockholders only for cause upon the vote of holders of 66 2/3% of the shares then entitled to vote at an election of directors. Furthermore, the authorized number of directors may be changed only by resolution of our board of directors, and vacancies and newly created directorships on our board of directors may, except as otherwise required by law or determined by our board, only be filled by a majority vote of the directors then serving on the board, even though less than a quorum. Our amended and restated certificate of incorporation and amended and restated bylaws provide that all stockholder actions must be effected at a duly called meeting of stockholders and not by a consent in writing. A special meeting of stockholders may be called only by a majority of our whole board of directors, the chair of our board of directors or our chief executive officer. Our amended and restated bylaws also provide that stockholders seeking to present proposals before a meeting of stockholders to nominate candidates for election as directors at a meeting of stockholders must provide timely advance notice in writing, and will specify requirements as to the form and content of a stockholder’s notice.
Our amended and restated certificate of incorporation further provides that the affirmative vote of holders of at least 66 2/3% of the voting power of all of the then outstanding shares of voting stock, voting as a single class, is required to amend certain provisions of our amended and restated certificate of incorporation, including provisions relating to the structure of our board of directors, the size of the board, removal of directors, special meetings of stockholders, actions by written consent and cumulative voting. The affirmative vote of holders of at least 66 2/3% of the voting power of all of the then outstanding shares of voting stock, voting as a single class, is required to amend or repeal our amended and restated bylaws, although our amended and restated bylaws may be amended by a simple majority vote of our whole board of directors.
The foregoing provisions will make it more difficult for our existing stockholders to replace our board of directors as well as for another party to obtain control of our company by replacing our board of directors. Since our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change the control of our company.
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These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and its policies and to discourage certain types of transactions that may involve an actual or threatened acquisition of our company. These provisions are also designed to reduce our vulnerability to an unsolicited acquisition proposal and to discourage certain tactics that may be used in proxy rights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of deterring hostile takeovers or delaying changes in control of our company or our management. As a consequence, these provisions also may inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts.
Choice of Forum
Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware will be the exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action or proceeding asserting a breach of fiduciary duty owed by any of our current or former directors, officers or employees to us or our stockholders; (3) any action or proceeding asserting a claim against us or any of our current or former directors, officers or other employees, arising out of or pursuant to the DGCL, our certificate of incorporation or our bylaws; (4) any action or proceeding to interpret, apply, enforce or determine the validity of our certificate of incorporation or our by-laws; or (5) any action or proceeding asserting a claim against us that is governed by the internal affairs doctrine, provided that, the exclusive forum provision will not apply to suits brought to enforce any liability or duty created by the Securities Act, the Exchange Act or any other claim for which the federal courts have exclusive jurisdiction; and provided further that, if and only if the Court of Chancery of the State of Delaware dismisses any such action for lack of subject matter jurisdiction, such action may be brought in another state or federal court sitting in the State of Delaware. It is possible that a court of law could rule that the choice of forum provision contained in our amended and restated certificate of incorporation is inapplicable or unenforceable if it is challenged in a proceeding or otherwise.
Listing
Our common stock is listed on the Nasdaq Global Market under the symbol “KROS.”
Transfer Agent and Registrar
The transfer agent and registrar for our common stock is Computershare Trust Company, N.A. The transfer agent’s address is 250 Royall Street, Canton, Massachusetts 02021. The transfer agent for any series of preferred stock that we may offer under this prospectus will be named and described in the prospectus supplement for that series.
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DESCRIPTION OF DEBT SECURITIES
We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below, and the applicable prospectus supplement, to the extent inconsistent with any portion of the description of our debt securities contained in this prospectus, will supersede the applicable portion of the description contained in this prospectus. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.
We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.
The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.
General
The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.
We may issue the debt securities issued under the indenture as “discount securities,” which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with “original issue discount,” or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.
We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:
the title of the series of debt securities;
any limit upon the aggregate principal amount that may be issued;
the maturity date or dates;
the form of the debt securities of the series;
the applicability of any guarantees;
whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;
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whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms of any subordination;
if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another security or the method by which any such portion shall be determined;
the interest rate or rates, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;
our right, if any, to defer payment of interest and the maximum length of any such deferral period;
if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;
the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder’s option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;
the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof;
any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt securities of that series;
whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities; the terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities; and the depositary for such global security or securities;
if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or how it will be calculated and may be adjusted, any mandatory or optional (at our option or the holders’ option) conversion or exchange features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;
if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall be payable upon declaration of acceleration of the maturity thereof;
additions to or changes in the covenants applicable to the particular debt securities being issued, including, among others, the consolidation, merger or sale covenant;
additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;
additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;
additions to or changes in the provisions relating to satisfaction and discharge of the indenture;
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additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders of debt securities issued under the indenture;
the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars;
whether interest will be payable in cash or additional debt securities at our or the holders’ option and the terms and conditions upon which the election may be made;
the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any, and principal amounts of the debt securities of the series to any holder that is not a “United States person” for federal tax purposes;
any restrictions on transfer, sale or assignment of the debt securities of the series; and
any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.
Conversion or Exchange Rights
We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.
Consolidation, Merger or Sale
Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.
Events of Default under the Indenture
Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:
if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable, and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;
if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;
if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and
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if specified events of bankruptcy, insolvency or reorganization occur.
If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.
The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.
Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:
the direction so given by the holder is not in conflict with any law or the applicable indenture; and
subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.
A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:
the holder has given written notice to the trustee of a continuing event of default with respect to that series;
the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request;
such holders have offered to the trustee indemnity satisfactory to it against the costs, expenses and liabilities to be incurred by the trustee in compliance with the request; and
the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.
These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.
We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.
Modification of Indenture; Waiver
We and the trustee may change an indenture without the consent of any holders with respect to specific matters:
to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;
to comply with the provisions described above under the heading “Description of Debt Securities—Consolidation, Merger or Sale;”
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to provide for uncertificated debt securities in addition to or in place of certificated debt securities;
to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred upon us in the indenture;
to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;
to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;
to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above under the heading “Description of Debt Securities-General” to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;
to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or
to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.
In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:
extending the fixed maturity of any debt securities of any series;
reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any series of any debt securities; or
reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.
Discharge
Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:
provide for payment;
register the transfer or exchange of debt securities of the series;
replace stolen, lost or mutilated debt securities of the series;
pay principal of and premium and interest on any debt securities of the series;
maintain paying agencies;
hold monies for payment in trust;
recover excess money held by the trustee;
compensate and indemnify the trustee; and
appoint any successor trustee.
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In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.
Form, Exchange and Transfer
We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.
At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.
Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.
We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.
If we elect to redeem the debt securities of any series, we will not be required to:
issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or
register the transfer of or exchange of any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.
Information Concerning the Trustee
The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.
Payment and Paying Agents
Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.
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We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.
All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.
Governing Law
The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.
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DESCRIPTION OF WARRANTS
The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock or debt securities and may be issued in one or more series. Warrants may be issued independently or together with common stock, preferred stock or debt securities offered by any prospectus supplement, and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement and any applicable free writing prospectus. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.
We have filed forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants that may be offered as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant and/or the warrant agreement and warrant certificate, as applicable, that contain the terms of the particular series of warrants we are offering and any supplemental agreements, before the issuance of such warrants. The following summaries of material terms and provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements applicable to a particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements that contain the terms of the warrants.
General
We will describe in the applicable prospectus supplement the terms relating to a series of warrants being offered, including:
the title of such securities;
the offering price or prices and aggregate number of warrants offered;
the currency or currencies for which the warrants may be purchased;
if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;
if applicable, the date on and after which the warrants and the related securities will be separately transferable;
if applicable, the minimum or maximum amount of such warrants which may be exercised at any one time;
in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at which, and currency in which, this principal amount of debt securities may be purchased upon such exercise;
in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which, and the currency in which, these shares may be purchased upon such exercise;
the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;
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the terms of any rights to redeem or call the warrants;
the terms of any rights to force the exercise of the warrants;
any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;
the dates on which the right to exercise the warrants will commence and expire;
the manner in which the warrant agreements and warrants may be modified;
a discussion of any material or special U.S. federal income tax consequences of holding or exercising the warrants;
the terms of the securities issuable upon exercise of the warrants; and
any other specific terms, preferences, rights or limitations of or restrictions on the warrants.
Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:
in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture; or
in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.
Exercise of Warrants
Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. The warrants may be exercised as set forth in the prospectus supplement relating to the warrants offered. Unless we otherwise specify in the applicable prospectus supplement, warrants may be exercised at any time up to the close of business on the expiration date set forth in the prospectus supplement relating to the warrants offered thereby. After the close of business on the expiration date, unexercised warrants will become void.
Upon receipt of the required payment and the warrant or warrant certificate, as applicable, properly completed and duly executed at the corporate trust office of the warrant agent, if any, or any other office, including ours, indicated in the applicable prospectus supplement, we will, as soon as practicable, issue and deliver the securities purchasable upon such exercise. If less than all of the warrants (or the warrants represented by such warrant certificate) are exercised, a new warrant or a new warrant certificate, as applicable, will be issued for the remaining amount.
Governing Law
Unless we provide otherwise in the applicable prospectus supplement, the warrants and any warrant agreements, and any claim, controversy or dispute arising under or related to the warrants or warrant agreements, will be governed by and construed in accordance with the laws of the State of New York.
Enforceability of Rights by Holders of Warrants
Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a
21


warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.
22


LEGAL OWNERSHIP OF SECURITIES
We may issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders and investors in securities issued in book-entry form or in street name will be indirect holders.
Book-Entry Holders
We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.
Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form, or global securities, will be registered in the name of the depositary or its participants. Consequently, for global securities, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.
As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.
Street Name Holders
A global security may be terminated in certain situations as described under “—Special Situations When a Global Security Will Be Terminated,” or issue securities that are not issued in global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.
For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not holders, of those securities.
Legal Holders
Our obligations, as well as the obligations of any applicable trustee or third party employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.
For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that legal holder is required, under agreements with its participants or customers or by
23


law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.
Special Considerations for Indirect Holders
If you hold securities through a bank, broker or other financial institution, either in book-entry form because the securities are represented by one or more global securities or in street name, you should check with your own institution to find out:
the performance of third-party service providers;
how it handles securities payments and notices;
whether it imposes fees or charges;
how it would handle a request for the holders’ consent, if ever required;
whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;
how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and
if the securities are in book-entry form, how the depositary’s rules and procedures will affect these matters.
Global Securities
A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.
Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.
A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under the heading “—Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and legal holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.
If the prospectus supplement for a particular security indicates that the security will be issued in global security form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.
Special Considerations for Global Securities
The rights of an indirect holder relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do
24


not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.
If securities are issued only in the form of a global security, an investor should be aware of the following:
an investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or her interest in the securities, except in the special situations we describe below;
an investor will be an indirect holder and must look to his or her own bank or broker for payments on the securities and protection of his or her legal rights relating to the securities, as we describe above;
an investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form;
an investor may not be able to pledge his or her interest in the global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;
the depositary’s policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor’s interest in the global security;
we and any applicable trustee have no responsibility for any aspect of the depositary’s actions or for its records of ownership interests in the global security, nor will we or any applicable trustee supervise the depositary in any way;
the depositary may, and we understand that DTC will, require that those who purchase and sell interests in the global security within its book-entry system use immediately available funds, and your broker or bank may require you to do so as well; and
financial institutions that participate in the depositary’s book-entry system, and through which an investor holds its interest in the global security, may also have their own policies affecting payments, notices and other matters relating to the securities.
There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.
Special Situations When a Global Security Will Be Terminated
In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own names, so that they will be direct holders. We have described the rights of holders and street name investors above.
Unless we provide otherwise in the applicable prospectus supplement, the global security will terminate when the following special situations occur:
if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;
if we notify any applicable trustee that we wish to terminate that global security; or
if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.
The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the applicable prospectus supplement. When a
25


global security terminates, the depositary, and neither we nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.
26


PLAN OF DISTRIBUTION
We may sell the securities from time to time pursuant to underwritten public offerings, direct sales to the public, negotiated transactions, block trades or a combination of these methods. We may sell the securities to or through one or more underwriters or dealers (acting as principal or agent), through agents, or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:
at a fixed price or prices, which may be changed;
at market prices prevailing at the time of sale;
at prices related to such prevailing market prices; or
at negotiated prices.
We may also sell equity securities covered by this registration statement in an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:
on or through the facilities of the Nasdaq Global Market or any other securities exchange or quotation or trading service on which such securities may be listed, quoted or traded at the time of sale; and/or
to or through a market maker other than on the Nasdaq Global Market or such other securities exchanges or quotation or trading services.
Such “at the market offerings”, if any, may be conducted by underwriters acting as principal or agent.
A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:
the name or names of any underwriters, dealers or agents, if any;
the purchase price of the securities or other consideration therefor, and the proceeds, if any, we will receive from the sale;
any over-allotment or other options under which underwriters may purchase additional securities from us;
any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;
any public offering price;
any discounts or concessions allowed or reallowed or paid to dealers; and
any securities exchange or market on which the securities may be listed.
Only underwriters named in the prospectus supplement will be underwriters of the securities offered by the prospectus supplement. Dealers and agents participating in the distribution of the securities may be deemed to be underwriters, and compensation received by them on resale of the securities may be deemed to be underwriting discounts. If such dealers or agents were deemed to be underwriters, they may be subject to statutory liabilities under the Securities Act.
If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus
27


supplement, other than securities covered by any option to purchase additional shares or other option. If a dealer is used in the sale of securities, we or an underwriter will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale. To the extent required, we will set forth in the prospectus supplement the name of the dealer and the terms of the transaction. Any public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may change from time to time.
We may use underwriters, dealers or agents with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, dealer or agent, the nature of any such relationship.
We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities, and we will describe any commissions payable to the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, the agent will act on a best-efforts basis for the period of its appointment.
We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.
We may provide agents, underwriters and dealers with indemnification against civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents, underwriters or dealers may make with respect to these liabilities. Agents, underwriters and dealers, or their affiliates, may engage in transactions with, or perform services for, us in the ordinary course of business.
Other than common stock, all securities we offer will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.
Any underwriter may be granted an option to purchase additional shares and engage in stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. An underwriter’s option to purchase additional shares involves sales in excess of the offering size, which creates a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the option to purchase additional shares or in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.
Any underwriters , dealers or agents that are qualified market makers on the Nasdaq Global Market may engage in passive market making transactions in the common stock on the Nasdaq Global Market in accordance with Regulation M under the Exchange Act, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.
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LEGAL MATTERS
Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the securities offered by this prospectus, and any supplement thereto, will be passed upon by Cooley LLP, Boston, Massachusetts. As of the date of this prospectus, an entity comprised of partners and associates of Cooley LLP beneficially own an aggregate of 3,722 shares of our common stock. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.
EXPERTS
The financial statements incorporated in this prospectus by reference from the Company’s Annual Report on Form 10-K, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report, which is incorporated herein by reference. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.
WHERE YOU CAN FIND MORE INFORMATION
This prospectus is part of the registration statement on Form S-3 we filed with the SEC under the Securities Act. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on the information contained in this prospectus or incorporated by reference. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered by this prospectus.
We must comply with the informational requirements of the Exchange Act, and we are required to file reports and proxy statements and other information with the SEC. You may read and copy these reports, proxy statements and other information on the SEC’s website at http://www.sec.gov, which contains reports, proxy and information statements and other information regarding issuers like us that file electronically with the SEC. We maintain a website at www.kerostx.com. The information contained in, or that can be accessed through, our website is not incorporated by reference herein and is not part of this prospectus.
Statements contained in this prospectus as to the contents of any contract or other document are not necessarily complete, and in each instance we refer you to the copy of the contract or document filed as an exhibit to the registration statement, each such statement being qualified in all respects by such reference.
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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus. We also incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information or documents listed below that we have filed with the SEC (Commission File No. 001-39264):
our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 25, 2021;
the portions of our Definitive Proxy Statement on Schedule 14A for our 2021 Annual Meeting of Stockholders specifically incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on April 19, 2021; and
the description of our common stock contained in our registration statement on Form 8-A filed with the SEC on April 3, 2020, including any amendments or reports filed for the purposes of updating this description, including Exhibit 4.3 to our Annual Report on Form 10-K for the year ended December 31, 2020.
We also incorporate by reference any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act until we file a post-effective amendment that indicates the termination of the offering of the securities made by this prospectus and will become a part of this prospectus from the date that such documents are filed with the SEC. Information in such future filings updates and supplements the information provided in this prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.
We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits which are specifically incorporated by reference into such documents. You should direct any requests for documents to Keros Therapeutics, Inc., Attn: Investor Relations, 99 Hayden Avenue, Suite 120, Building E, Lexington, Massachusetts 02421.
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3,500,000 Shares
keroslogo1a.jpg
Common Stock
PROSPECTUS SUPPLEMENT
Joint Book-Running Managers
Goldman Sachs & Co. LLCLeerink PartnersPiper SandlerTruist Securities
January 3, 2024

Exhibit 107
Calculation of Filing Fee Tables
424(b)(5)
(Form Type)
Keros Therapeutics, Inc.
(Exact Name of Registrant as Specified in its Charter)
Table 1: Newly Registered and Carry Forward Securities
Security
Type
Security
Class
Title
Fee
Calculation
or Carry
Forward
Rule
Amount
Registered
Proposed
Maximum
Offering
Price Per
Unit
Maximum
Aggregate
Offering
Price
Fee
Rate
Amount of
Registration
Fee
Carry
Forward
Form
Type
Carry
Forward
File
Number
Carry
Forward
Initial
Effective
Date
Filing Fee
Previously
Paid In
Connection
with Unsold
Securities to
be Carried
Forward
Newly Registered Securities
Feeds to be
Paid
EquityCommon stock, $0.0001 par value per shareRule 457(r)
4,025,000(2)
$40.00
$161,000,000
$147.60 per $1,000,000$23,764
Fees
Previously
Paid
Carry Forward Securities
Carry
Forward
Securities
Total Offering Amounts 
$23,764 (1)
Total Fees Previously Paid 
Total Fee Offsets 
Net Fee Due $23,764
(1)This “Calculation of Registration Fee” table shall be deemed to update the “Calculation of Registration Fee” table in the registrant’s Registration Statement on Form S-3ASR (File No. 333-255724), which was filed on May 3, 2021, in accordance with Rules 456(b) and 457(r) under the Securities Act of 1933, as amended. The prospectus supplement to which this exhibit is attached is a final prospectus for the related offering.
(2)Includes 525,000 shares of common stock issuable upon exercise of the underwriters’ option to purchase additional shares of common stock.


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