RETA Reata Pharmaceuticals Inc

CUSIP No.: 75615P 10 3

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This amendment (“ Amendment No.  5 ”) amends the Schedule 13D originally filed with the Commission on June 2, 2016, as subsequently amended by Amendment No. 1 filed on August 5, 2016, Amendment No. 2 filed on December 9, 2016, Amendment No. 3 filed on March 3, 2017 and Amendment No. 4 filed on June 15, 2017 (collectively, the “ Amended Schedule ”), to update the directors and executive officers of the Reporting Person on Schedule I and to report a decrease in beneficial ownership of the Class A common stock of the Issuer held by Novo Holdings A/S resulting from the private sale of shares by Novo Holdings A/S. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Amended Schedule.

Item 2. Identity and Background

Item 2 of the Schedule is amended and replaced in its entirety as follows:

The name of each director and executive officer of both Novo and the Foundation is set forth on Schedule I to this Amendment No. 5.

The residence or business address of each director and executive officer of both Novo and the Foundation is set forth on Schedule I to this Amendment No. 5.

The Foundation is a Danish self-governing and profit-making foundation, whose objectives are to provide a stable basis for commercial and research activities undertaken by the group of Novo companies and to support scientific, humanitarian and social purposes through grants.

Item 5. Interest in Securities of the Issuer

Item 5(a) of the Schedule is amended and replaced in its entirety as follows:

(a) Novo is deemed to beneficially owns an aggregate of 1,794,763 shares of Class A common stock, comprised of 592,794 shares of Class A common stock and 1,201,969 shares of Class B common stock (the “ Novo Shares ”), representing 11.3% of the Class A common stock based on conversion of only the 1,201,969 shares of Class B common stock held by the Novo into Class A common stock on a one-for-one basis. The Class B common stock converts on a one-for-one basis into Class A common stock at the election of the holder and upon any sale or transfer, subject to certain exceptions. Assuming all outstanding 7,631,743 shares of Class B common

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stock are converted into Class A common stock, Novo would beneficially own 8.0% of the Class A common stock. The foregoing percentage ownership calculations are based upon 14,733,864 shares of Class A common stock and 7,631,743 shares of Class B common stock outstanding as of June 23, 2017, based on information reported in the Issuer’s Quarterly Report on Form 10-Q filed with the Commission on May 10, 2017, and assuming automatic conversion of 742,289 shares of Class B common stock upon the Sale (as defined below) based on information provided by the Issuer.

Item 5(b) of the Schedule is amended and replaced in its entirety as follows:

(b) Novo is a Danish limited liability company wholly owned by the Foundation. Novo, through its Board of Directors (the “ Novo Board ”), has the sole power to vote and dispose of the Novo Shares. The Novo Board, currently comprised of Sten Scheibye, Goran Ando, Jeppe Christiansen, Steen Riisgaard, Lars Rebien Sørensen and Per Wold-Olsen, may exercise voting and dispositive control over the Novo Shares only with the support of a majority of the Novo Board. As such, no individual member of the Novo Board is deemed to hold any beneficial ownership or reportable pecuniary interest in the Novo Shares. Except as described in this Amendment No. 5, neither the Foundation, Novo nor any of their respective directors or executive officers has the power to direct the vote as to, or the disposition of the Novo Shares.

Item 5(c) of the Schedule is supplemented as follows:

(c) On June 22, 2017, Novo entered into a Purchase Agreement with the Issuer and certain funds affiliated with CPMG, Inc., a Texas Corporation (“ CPMG ”), R. Kent McGaughy Jr., and James W. Traweek, Jr. listed on Schedule I to the Purchase Agreement (collectively, the “ CPMG Purchasers ”) for the sale by Novo to the CPMG Purchasers of 1,200,000 shares of the Issuer’s Class B common stock for $25.00 per share (the “ Sale ”). The closing of the Sale is scheduled to occur on or before June 29, 2017, subject to completion of customary deliveries. In accordance with the Issuer’s Thirteenth Amended and Restated Certificate of Incorporation, promptly following the closing of the Sale, 742,289 shares of the 1,200,000 shares of Class B common stock sold by Novo will convert to shares of Class A common stock, with 457,711 shares remaining as Class B common stock.

Other than the Sale and the sales previously reported on the Amended Schedule, Novo has not effected any transactions in the Issuer’s Common Stock within the past 60 days and neither the Foundation nor any person listed on Schedule I has effected any transactions in the Issuer’s Common Stock within the past 60 days.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Item 6 of the Schedule is amended and supplemented by the following:

On June 22, 2017, Novo entered into a Purchase Agreement with the Issuer and the CPMG Purchasers for the Sale by Novo to the CPMG Purchasers of 1,200,000 shares of the Issuer’s Class B common stock for $25.00 per share. The closing of the Sale is scheduled to occur on or before June 29, 2017, subject to completion of customary deliveries. The Purchase Agreement contained standard representations and warranties.

In connection with the Sale, Novo entered into a Lock-up Agreement with the Issuer dated June 22, 2017 (“ Lock-Up Agreement ”) with respect to a potential firm commitment underwritten public offering by the Issuer (the “ Offering ”). Under the Lock-Up Agreement, Novo agreed that during the “Lock-Up Period” as defined below and subject to certain limited exceptions specified in the Lock-Up Agreement, Novo will not, without the prior consent of the Issuer, offer, sell, contract to sell, pledge or otherwise dispose of (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition directly or indirectly of), including the filing of a registration statement (other than the registration statement relating to the Offering by the Issuer) with the Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position for, any shares of capital stock of the Issuer. The “Lock-Up Period” commenced on June 22, 2017 and continues until the earlier of (a) 90 days after the signing date of the underwriting agreement for the Offering and (b) December 15, 2017.

In connection with the Sale, Novo executed a Registration Rights Agreement Acknowledgement and Waiver dated June 22, 2017 (the “ Waiver ”), with respect to the registration statement on Form S-3 expected to be filed by the Issuer on or about June 23, 2017 (the “ Registration Statement ”) and the potential one or more underwritten offerings, at-the market offerings, or other types of distributions permitted pursuant to the prospectus included in the Registration Statement (collectively, the “ Proposed Offerings ”). Under the Waiver, Novo declined to

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exercise and waived its rights under Section 3.1 of the Registration Rights Agreement with respect to the inclusion of any of Novo’s Registrable Securities in the Registration Statement or any Proposed Offerings. Novo further waived any defects in the notice obligations required under the Registration Rights Agreement related to the Registration Statement or the Proposed Offerings. The Waiver will be null and void as of September 1, 2017, if the Registration Statement has not been filed on or before such date.

Except for the Registration Rights Agreement described in the Amended Schedule, the Purchase Agreement, the Waiver and the Lock-Up Agreement, neither Novo, the Foundation, nor any person named in Schedule I has entered into any contracts, arrangements, understandings or relationships with respect to securities of the Issuer

Item 7. Material to be Filed as Exhibits.

Exhibit A – Purchase Agreement dated June 22, 2017

Exhibit B – Lock-Up Agreement dated June 22, 2017

Exhibit C – Registration Rights Agreement Acknowledgement and Waiver dated June 22, 2017

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Schedule I

Information regarding each director and executive officer of both Novo Holdings A/S and the Novo Nordisk Foundation is set forth below.