GBCI Glacier Bancorp Inc

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This document, including information included or incorporated by reference in this document may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to: (i) statements about the benefits of the merger, including future financial and operating results, cost savings, enhancements to revenue and accretion to reported earnings that may be realized from the merger; (ii) statements about Glacier’s and AB’s plans, objectives, expectations, intentions, projected financial information, future opportunities and any other statements regarding Glacier’s and AB’s future expectations, beliefs, plans, objectives, results of operations, financial condition and cash flows that are not historical facts; (iii) the expected timetable for completing the merger; (iv) the ability to complete the merger; and (v) other statements identified by words such as “expects,” “anticipates,” “intends,” “plans,” “believes,” “seeks,” “estimates,” or words of similar meaning. These forward-looking statements are based on current beliefs and expectations of Glacier’s and AB’s management and are inherently subject to significant business, economic and competitive uncertainties and contingencies, many of which are beyond Glacier’s and AB’s control. In addition, these forward-looking statements are subject to assumptions with respect to future business strategies and decisions that are subject to change.

In addition to factors previously disclosed in Glacier’s and AB’s reports filed with the SEC relating to risks to Glacier’s and AB’s business and stock price, and those identified elsewhere in this document (including the section entitled “Risk Factors”), the following potential factors, among others, could cause actual results to differ materially from the anticipated results or other expectations expressed or implied in the forward-looking statements:

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The foregoing list of factors is not intended to be exhaustive. These forward-looking statements reflect Glacier’s and AB’s current views with respect to future events and are based on numerous assumptions and assessments made by Glacier and AB in light of their experiences and perceptions of historical trends, current conditions, business strategies, operating environments, future developments and other factors they believe appropriate. By their nature, forward-looking statements involve known and unknown risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. The factors described in the context of such forward-looking statements in this document could cause Glacier’s and AB’s plans with respect to the merger, actual results, performance or achievements, industry results and developments to differ materially from those expressed in or implied by such forward-looking statements. Although it is believed that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct and persons reading this document are therefore cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this proxy statement/prospectus or, in the case of a document incorporated by reference, as of the date of that document. All subsequent written and oral forward-looking statements concerning the proposed transaction or other matters attributable to Glacier or AB or any person acting on behalf of Glacier or AB are expressly qualified in their entirety by the cautionary statements above. Neither Glacier nor AB undertakes any obligation to update any forward-looking statements to reflect circumstances or events that occur after the date the forward-looking statements are made.

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COMPARATIVE STOCK PRICE AND DIVIDEND INFORMATION

The following table sets forth the closing sale prices per share of Glacier common stock and AB common shares on May 17, 2021, the last trading day before the public announcement of the signing of the merger agreement, and on July 15, 2021, the latest practicable trading day before the printing date of this joint proxy statement/prospectus. The table also shows the implied value of the merger consideration payable for each AB common share on May 17, 2021 and on July 15, 2021, the latest practicable trading day before the printing date of this joint proxy statement/prospectus, determined by multiplying the closing price of the Glacier common stock on such dates by the exchange ratio of 0.7971.

As of the record date, the 18,882,463 outstanding AB common shares were held by approximately 3,266 holders of record, including (1) 726 registered holders (including registered holders with shares in the Altabancorp Employee Stock Ownership Plan, as amended (the “ESOP”), which shareholders may also hold shares separately outside of the ESOP), and (ii) 2,540 beneficial holders. As of the record date, the 95,507,234 outstanding shares of Glacier common stock were held by approximately 1,890 holders of record.

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AB SPECIAL SHAREHOLDERS’ MEETING

Date, Time, Place

The AB special meeting of shareholders will be held on August 31, 2021, at 8:00 a.m. Mountain Time. The special meeting will be held in virtual meeting format only. In order to attend the special meeting, AB shareholders must register at www.proxydocs.com/ALTA by 5:00 p.m. Mountain Time on August 27, 2021.

As described below under the “Votes Required and Quorum,” approval of the merger agreement requires the affirmative vote of at least a majority of the outstanding shares of AB’s common stock entitled to vote on the matter. The proposal to approve merger-related compensation to named executives on an advisory basis will be approved if the votes cast in favor of the proposal exceed the votes cast opposing the proposal, assuming a quorum is present. The proposal to adjourn the special meeting, if necessary or appropriate, including adjournments to solicit additional proxies, will be approved if the votes cast in favor of the proposal exceed the votes cast opposing the proposal, whether or not a quorum is present.

Purpose

At the special meeting, AB shareholders will:

Record Date; Shares Outstanding and Entitled to Vote

The AB Board has fixed the close of business on July 14, 2021, as the record date for determining the holders of AB common shares entitled to notice of and to vote at the special meeting. At the close of business on the record date, there were approximately 3,266 holders of record and 18,882,463 AB common shares issued and outstanding. Holders of record of AB common shares on the record date are entitled to one vote per share. Unvested RSUs do not have voting rights.

AB’s directors and executive officers and certain significant shareholders have agreed to vote all AB common shares they are entitled to vote that are held or controlled by them in favor of approval of the merger agreement. As of the record date, to AB’s knowledge, a total of 7,724,949 AB common shares, representing approximately 41% of all outstanding AB common shares are subject to voting agreements. See “The Merger – Voting Agreements”.

Votes Required and Quorum

The affirmative vote of the holders of at least a majority of the outstanding shares of AB’s common stock entitled to vote is required to approve the merger agreement. At least a majority of the total outstanding AB common shares entitled to vote must be present, either at the meeting or by proxy, in order to constitute a quorum for the special meeting. For purposes of determining a quorum, abstentions and broker non-votes will be counted in determining the shares present at a meeting.

For voting purposes, however, shares must be affirmatively voted FOR approval of the merger agreement in order to be counted as votes in favor of the merger. As a result, abstentions and broker non-votes with respect to the proposal to approve the merger agreement will have the same effect as votes against such proposal.

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With respect to the merger-related named executive compensation proposal, approval of such proposal requires that the votes cast in favor of the proposal exceed the votes cast opposing the proposal. As a result, abstentions and broker non-votes with respect to the merger-related named executive officer compensation proposal will have no effect on the merger-related named executive officer compensation proposal.

With respect to the proposal to adjourn the special meeting if necessary or appropriate, if a quorum is not present at the special meeting, shareholders entitled to vote at the special meeting, present at the meeting or by proxy, will have the power to adjourn the special meeting. If a quorum is present at the special meeting, the proposal to adjourn the special meeting, if necessary or appropriate, including an adjournment to solicit additional proxies in favor of the merger agreement, will be approved if the votes cast in favor of the proposal exceed the votes cast opposing the proposal.

Voting, Solicitation, and Revocation of Proxies

If you are a holder of record of AB common shares as of the record date for the special meeting, there are four ways to have your shares voted:

If the enclosed proxy card is duly executed and received in time for the special meeting, it will be voted in accordance with the instructions given. If the proxy card is duly executed and received but no instructions are given, it is the intention of the persons named in the proxy to vote the shares represented by the proxy FOR the approval of the merger agreement, FOR the proposal to approve merger-related compensation of AB’s named executive officers and FOR the proposal to approve one or more adjournments to solicit additional proxies, and in the proxy holder’s discretion on any other matter properly coming before the meeting. Any proxy given by a shareholder may be revoked before its exercise by:

AB is soliciting the proxy for the special meeting on behalf of the AB Board. AB will bear the cost of solicitation of proxies from its shareholders. In addition to using the mail, AB may solicit proxies by personal interview, telephone, and facsimile. Banks, brokerage houses, other institutions, nominees, and fiduciaries will be requested to forward their proxy soliciting material to their principals and obtain authorization for the execution of proxies. AB will, upon request, pay the standard charges and expenses of banks, brokerage houses, other institutions, nominees, and fiduciaries for forwarding proxy materials to and obtaining proxies from their principals.

Voting at the Special Meeting

Shares held directly in your name as the shareholder of record may be voted during the special meeting by following the instructions available on the meeting website. Even if you plan to participate at the virtual special

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meeting, AB recommends that you vote your AB common shares in advance as described above so that your vote will be counted if you later decide not to attend the special meeting.

If your shares are registered in “street name” in the name of a broker or other nominee and you wish to vote during the special meeting, you will need to obtain a legal proxy from your bank or brokerage firm. Please consult the voting form sent to you by your bank or broker to determine how to obtain a legal proxy in order to vote at the meeting.

The AB Proposals

Proposal 1: Merger Proposal

AB is asking its shareholders to approve the merger agreement. For a detailed discussion of the terms and conditions of the merger agreement, please see the section entitled “The Merger.” AB shareholders should read this proxy statement/prospectus, including any documents incorporated in this proxy statement/prospectus by reference, and its annexes, carefully and in their entirety for more detailed information concerning the merger agreement and the merger. A copy of the merger agreement is attached to this proxy statement/prospectus as Appendix A.

As discussed in the section entitled “Background of and Reasons for the Merger,” after careful consideration, the AB Board approved the execution, delivery and performance of the merger agreement and the transactions contemplated by it, including the merger, and determined the merger to be fair and in the best interests of AB and the AB shareholders.

Required Vote

Approval of the proposal to approve the merger agreement requires the affirmative vote of at least a majority of the outstanding shares of AB’s common stock entitled to vote. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or via remote participation through the virtual format of the meeting at the AB special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have the same effect as votes against the merger proposal.

The approval of the merger by holders of AB common shares is a condition to the completion of the merger.

The AB Board recommends that AB shareholders vote “FOR” the proposal to approve the merger agreement.

Proposal 2: Advisory Proposal to Approve Merger-Related Named Executive Officer Compensation

Pursuant to Section 14A of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), AB is providing its shareholders with the opportunity to cast an advisory (non-binding) vote to approve the compensation that may be paid or become payable to its named executive officers that is based on or otherwise relates to the merger, as disclosed in the section entitled “The Merger—Interests of AB Directors and Executive Officers in the Merger.” As required by Section 14A of the Exchange Act, AB is asking its shareholders to vote to adopt the following resolution:

“RESOLVED, that the compensation that may be paid or become payable to AB’s named executive officers that is based on or otherwise relates to the merger, and the agreements or understandings pursuant to which such compensation may be paid or become payable, in each case as disclosed pursuant to Item 402(t) of Regulation S-K in the section of the proxy statement/prospectus statement entitled “The Merger—Merger-Related Compensation for AB’s Named Executive Officers”, are hereby APPROVED.”

Required Vote

Approval of the advisory proposal to approve merger-related named executive officer compensation requires that the number of votes cast in favor of the proposal exceed the votes cast opposing the proposal,

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assuming a quorum is present. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or via remote participation through the virtual format of the meeting at the AB special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have no effect on the merger-related named executive officer compensation proposal.

The vote to approve the merger-related named executive officer compensation proposal is a vote separate and apart from the vote to approve the merger agreement. Accordingly, a shareholder may vote to approve the merger-related named executive officer compensation proposal and vote not to approve the merger agreement or vice versa. Because the merger-related named executive officer compensation proposal vote is advisory only, it will not be binding on the parties to the merger. If the merger is completed, the merger-related named executive officer compensation subject to the merger-related named executive officer compensation proposal will be paid to AB’s named executive officers to the extent payable in accordance with the terms of the applicable compensation agreements and arrangements even if holders of AB common shares fail to approve the merger-related named executive officer compensation proposal.

The approval of the merger-related named executive officer compensation proposal is not a condition to the completion of the merger.

The AB Board recommends a vote “FOR” the proposal to approve merger-related compensation of AB’s named executive officers.

Proposal 3: Adjournment Proposal

AB is asking its shareholders to approve the adjournment of the AB special meeting to another date and place if necessary or appropriate to solicit additional votes in favor of the merger proposal if there are insufficient votes at the time of such adjournment to approve the merger proposal.

If, at the AB special meeting, an insufficient number of AB common shares are present via remote participation through the virtual format of the meeting or represented by proxy and voting in favor of the merger proposal, AB will move to adjourn the AB special meeting to enable the AB Board to solicit additional proxies for approval of the merger proposal. If the AB shareholders approve the adjournment proposal, AB may adjourn the AB special meeting and use the additional time to solicit additional proxies, including the solicitation of proxies from AB shareholders who have previously voted. If the date of the adjournment is not announced at the AB special meeting or a new record date is fixed for the adjourned meeting, a new notice of the adjourned meeting will be given to each shareholder of record entitled to vote at the adjourned meeting.

Required Vote

Approval of the adjournment proposal requires that the number of votes cast in favor of the proposal exceed the votes cast opposing the proposal, whether or not a quorum is present. If you mark “ABSTAIN” on your proxy card, fail to submit a proxy card or fail to vote by mail, by telephone, via the Internet, or via remote participation through the virtual format of the meeting at the AB special meeting, or are a “street name” holder and fail to instruct your bank, broker, or other nominee how to vote, it will have no effect on the adjournment proposal.

The AB Board recommends that AB shareholders vote “FOR” the adjournment proposal.

Other Matters to Come Before the AB Special Meeting

As of the date of this proxy statement/prospectus, the AB Board is not aware of any matters that will be presented for consideration at the AB special meeting other than as described in this proxy statement/prospectus. If, however, the AB Board properly brings any other matters before the AB special meeting, the persons named in the proxy will vote the shares represented thereby in accordance with the recommendation of the AB Board on any such matter.

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BACKGROUND OF AND REASONS FOR THE MERGER

Background of the Merger

The AB Board, with the assistance of executive management, periodically reviews, assesses, and discusses AB’s strategic direction, performance, and prospects. These reviews and discussions have included from time to time, third party advisors, including investment bankers and external legal counsel, and have addressed the potential strategic alternatives that might be available to AB, including organic growth opportunities, potential mergers and acquisitions (including potential acquisition targets and the sale of AB), and capital planning decisions, all with the goal of enhancing shareholder value. These reviews and discussions have also included analyses of the business environment for financial institutions, including technology initiatives and investments, the impact of low interest rates, the evolution of community banking, and talent acquisition and retention. Economic outlook nationally and locally, the regulatory and compliance environment, financial institution industry trends, peer comparisons, ongoing consolidation among financial institutions, and the benefits and risks of continued operation as a standalone company have also been considered. Factors assessed in connection with these reviews have included the risks and opportunities associated with operating in existing and new markets, competition, potential positive and negative expense and revenue synergies, regulatory requirements, interest rate environment and prospects, scale, operational risk, credit risk, market risk, and changes in technology and in delivery and marketing channels. In connection with the evaluation of strategic alternatives, AB’s executive management has had, from time to time, informal discussions, including regarding potential acquisitions or the sale of AB, with representatives of other financial institutions and has regularly updated the AB Board regarding such discussions.

Randall M. Chesler, President and Chief Executive Officer of Glacier, and Len E. Williams, President and Chief Executive Officer of AB, have lengthy careers in the financial institutions industry and have known each other professionally for the last two to three years since Mr. Williams joined AB. Messrs. Chesler and Williams have periodically informally discussed matters of mutual interest to their respective institutions, and Mr. Chesler inquired on at least one occasion about a potential business combination.

Certain members of the Gunther family and their related entities (the “Section 13D Group”) executed a shareholder agreement on January 28, 2020 and jointly filed a Schedule 13D with the Securities & Exchange Commission on June 12, 2020. At the time, two of the 10 members of the AB Board were part of the Section 13D Group.

To avoid potential conflicts of interest and to advance the best interests of the company and its shareholders, in July of 2020, all 10 members of the AB Board unanimously voted to establish a special committee comprising all directors other than the directors that were members of the Section 13D Group to act on behalf of the company with respect to considering and responding to the goals and requests of the Section 13D Group.

In August 2020, the AB Board convened its regularly scheduled annual two-day retreat to review, assess, and set the company’s strategic direction. As is customary practice, the AB Board, with the assistance of executive management, considered and set various key strategic objectives for the company. In addition, the AB Board and executive management considered and discussed the contents and potential impacts of the Schedule 13D filing by the Section 13D Group. After considering the positive performance trajectory of the company, the successful implementation of technology initiatives, and the experience and capabilities of executive management, among other factors, the AB Board adopted and endorsed the strategic direction for the company, including to remain independent and pursue organic growth and potential acquisition opportunities.

In November 2020, executive management presented an opportunity to acquire a bank outside of the state of Utah. The AB Board unanimously directed executive management to begin formal discussions with Party X regarding a potential acquisition.

During the course of the next several months, at regularly-scheduled Board meetings and through periodic communications with the AB Board, executive management provided the AB Board updates on unsolicited

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contacts and inquiries from third parties regarding a possible sale of the company, including unsolicited approaches from Glacier and Party B, key metrics on the company’s strategic direction adopted at the AB Board’s annual retreat, and progress on various potential acquisition opportunities.

On January 11, 2021, the AB Board unanimously approved the submission of a non-binding letter of interest to Party X regarding the acquisition of Party X by AB.

On January 15, 2021, Paul Gunther, a member of the Section 13D Group, resigned as a director of AB.

At a special meeting convened on January 15, 2021, the AB Board considered and discussed the strategic objectives of the company. Mr. Williams also provided an update to the AB Board on potential acquisition opportunities. In addition, the AB Board considered and discussed the amended Schedule 13D filed by the Section 13D Group on January 14, 2021, which included a letter to the AB Board requesting that the AB Board review strategic alternatives for AB, including a potential sale of the company. The filing also noted the 13D Group’s objection to AB acquiring another bank and its concern that the current Board of Directors and executive management would be incapable of successfully executing such a transaction. Keefe, Bruyette & Woods, Inc., acting as financial advisor to AB (“KBW”), was invited to the meeting to discuss with the AB Board the potential process for undertaking a review of the company’s strategic alternatives and how KBW could assist in that review.

At its regularly-scheduled meeting on January 26, 2021, the AB Board received a presentation from Jones Day, legal counsel to AB, regarding the directors’ fiduciary duties under applicable law and related obligations in reviewing and considering strategic alternatives, which was followed by review and discussion with KBW of strategic considerations and the following alternatives: (i) remain standalone/independent; (ii) pursue mergers and acquisitions; (iii) explore a merger of equals; or (iv) undertake a controlled sale process. The market landscape, potential targets, prospective buyers, valuation considerations, and related financial considerations were reviewed and discussed. The AB Board met in executive session to discuss the foregoing, after which the AB Board voted unanimously to continue with the strategic direction previously agreed to in August 2020 at the AB Board’s annual retreat, mainly to remain as an independent entity and pursue potential acquisition opportunities, including the potential acquisition of Party X.

On January 27, 2021, the Section 13D Group filed an amended Schedule 13D, which included a letter to the AB Board, reiterating the Section 13D Group’s request that AB review strategic alternatives, including a potential sale of the company.

On February 1, 2021, Jonathan Gunther, a member of the Section 13D Group, resigned as a director of AB.

At a special meeting convened on February 11, 2021, The AB Board considered recent developments, including the ongoing consolidation among financial institutions, executive management’s ongoing discussions regarding a potential acquisition opportunity, and the significant potential costs likely to be incurred by AB and the potential disruption to AB’s business in the event of a proxy contest. The AB Board discussed the company’s strategic alternatives in light of these developments and how best to further validate the best future strategy for AB. The AB Board determined to direct KBW to (i) approach prospective buyers to solicit interest in a possible sale of the company and also (ii) to concurrently continue to move forward with a potential acquisition of Party X.

At the direction of the AB Board, on February 16, 2021 executive management, with the assistance of KBW, commenced the solicitation process for a possible sale of AB. Continuing over the course of several days, representatives of KBW contacted or were contacted by potential counterparties, including Glacier. With KBW’s assistance, the AB Board and executive management identified potential buyers of AB with (i) the greatest financial ability to pay (based on their relative buying power versus third parties, as determined based on publicly available information) and (ii) a similar strategic direction and culture as AB. Each of the nine potential

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counterparties received initial marketing information and draft non-disclosure agreements. Ultimately, seven of those parties expressed interest in the potential acquisition of AB, executed customary non-disclosure agreements, received preliminary due diligence information, and received a process letter requesting indications of interest by March 12, 2021. Of the parties that executed a non-disclosure agreement, four parties elected to receive a management presentation and meeting.

At its regularly-scheduled meeting on February 24, 2021, the AB Board received an update from KBW regarding the sale process, including preliminary due diligence performed by interested counterparties, and the anticipated timeline for indications of interest, as well as an update from executive management on the company’s concurrent pursuit of a potential acquisition of Party X.

During the period from March 2, 2021 to March 5, 2021, AB conducted management presentations and meetings with Glacier, Party A, Party B, and Party C.

On March 8, 2021, Glacier’s executive management team and D.A. Davidson & Co., financial advisor to Glacier (“D.A. Davidson”), met with the Glacier board of directors to discuss the pro forma financial modeling and approach to submitting a letter of intent later in the week. D.A. Davidson also discussed pricing strategies based on other interested banks’ ability to pay, as well as Glacier’s pricing differentiation versus the other banks needed to encourage AB to conclude the process in one round and move forward with Glacier.

At a special meeting convened on March 15, 2021, KBW reviewed with the AB Board the process undertaken to date by AB, with KBW’s assistance, in respect of a potential sale of the company. AB received indications of interest to acquire AB from (i) Glacier indicating an all-stock proposal (with the potential for a special cash dividend based on the amount of AB capital and certain other amounts at closing) at a fixed exchange ratio of 0.7971 shares of Glacier common stock for each AB common share, which (excluding any special cash dividend) represented an implied per share value of approximately $53.01 per share and an implied 37.2% premium to AB’s stock price at such time, (ii) Party A indicating an all-stock offer at a fixed exchange ratio which represented an implied per share value of approximately $48.58 per share and an implied 25.8% premium to AB’s stock price at such time, (iii) Party B indicating an all-stock offer at a fixed exchange ratio which represented an implied per share value of approximately $43.62 per share and an implied 12.9% premium to AB’s stock price at such time, and (iv) Party C indicating an all-stock offer (though Party C expressed a willingness to discuss a mix of cash and stock) at a fixed exchange ratio which represented an implied per share value of approximately $42.73 per share and an implied 10.6% premium to AB’s stock price at such time. In order to present all of the indications of interest on a per share dollar basis, certain assumptions regarding AB’s share count, AB’s share price, and the share price of the applicable potential counterparty were made. The AB Board discussed and reviewed each of the indications of interest with AB’s executive management, KBW, and Jones Day. The AB Board, with input received from management and its external advisors, discussed (i) that the Glacier proposal was more than 9% higher than the next highest proposal received from Party A, (ii) the low prospect that a superior bid could be found because (x) potential counterparties identified by AB, with KBW’s assistance, were selected on the basis of the greatest financial ability to pay (based on their relative buying power versus third parties, as determined based on publicly available information) and (y) the 37.2% premium to AB’s stock price at such time (excluding any special cash dividend) was higher than the significant majority of the previously announced bank M&A transactions reviewed with the AB Board by KBW, and (iii) that Glacier has successfully completed over a dozen acquisitions of similar banks on a set of terms and conditions that were substantially similar to one another. The AB Board considered the possibility of seeking to further negotiate the stock consideration offered by the various bidders but in light of the prices proposed and ability of each bidder to pay, the AB Board ultimately concluded that it was more advisable to proceed with the transaction proposed by Glacier. Jones Day advised the AB Board regarding their fiduciary duties under applicable law. The AB Board then unanimously voted to authorize management of the company to proceed to pursue and negotiate a business combination transaction with Glacier and to discontinue discussions regarding a potential acquisition of Party X.

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Also on March 15, 2021, the Section 13D Group filed an amended Schedule 13D, which included a letter to AB’s shareholders, announcing the Section 13D group’s intention to consider a “vote no” campaign against certain of AB’s directors.

KBW informed Glacier of the AB Board’s decision to pursue and negotiate a business combination transaction with Glacier on March 16, 2021. Executive management representatives of Glacier and AB negotiated and discussed additional deal terms within the parameters discussed with the AB Board over the course of the next several business days, including, without limitation, the amount of Glacier’s requested termination fee and the duration of the exclusivity period to be granted to Glacier for purposes of negotiating a definitive agreement. On March 18, 2021, the parties executed a letter of intent.

Commencing March 22, 2021 and continuing through May 18, 2021, Messrs. Chesler and Williams and other executive management representatives from Glacier and AB, respectively, had periodic telephonic meetings to discuss and negotiate the terms of the merger and potential integration. During this period, Glacier performed extensive diligence of AB, and AB, in turn, undertook reverse diligence of Glacier during this time period. During the diligence process, various working groups from Glacier and AB, including information technology, accounting, retail operations, legal and compliance, credit, human resources, marketing, internal audit, data warehouse, and commercial banking, met virtually to exchange information and discuss the proposed transaction. Representatives of KBW and D.A. Davidson also attended many of these meetings.

At the regularly-scheduled AB Board meeting on March 31, 2021, Mr. Williams provided the AB Board an update regarding the proposed merger transaction, including the status of due diligence and various potential integration matters. The potential negative impact of the recent decline in Glacier’s stock price, as well as the interest rate effect on the fair valuation of investment securities available for sale and the corresponding recording of the unrealized gain or loss to shareholders’ equity, on the transaction’s economics were discussed. A special meeting of the AB Board was convened on April 1, 2021 to discuss the transaction’s economics further. After consultation with and input from executive management, Jones Day, and KBW, the AB Board directed executive management of the company to move forward with due diligence and KBW and executive management of the company to continue to monitor closely the transaction economics.

On April 16, 2021, Miller Nash LLP, legal counsel to Glacier (“Miller Nash”), provided an initial draft of the merger agreement. Between that receipt date and May 14, 2021, Miller Nash and Jones Day exchanged drafts of the merger agreement and other transaction documents, including voting agreements to be entered into by each of the directors and each of the executive officers of AB and certain other shareholders of AB and non-compete/non-solicitation agreements to be entered into by each of the directors. The two law firms and the respective management teams negotiated, exchanged drafts, and worked towards finalizing the terms and conditions of the merger agreement, the voting agreements and other transaction documents. AB negotiated with Glacier to obtain more favorable terms and conditions in the merger agreement. Reciprocal due diligence continued during this time period as well.

At the April 28, 2021 regularly-scheduled AB Board meeting, Mr. Williams provided the AB Board a detailed update regarding the proposed merger transaction, including the status of due diligence, negotiation of the merger agreement, and various operational and integration matters. With participation from Jones Day, the AB Board reviewed and discussed the negotiation of key terms of the draft merger agreement, proposed voting agreements for executive officers and directors, and proposed non-compete/non-solicitation agreements for directors. The AB Board considered the governance structure of Glacier, including its board of directors as well as its divisional board structure. The AB Board discussed a proposed timeline for completing negotiation and anticipated next steps and directed KBW to meet with D.A. Davidson and Glacier regarding the transaction and the impact of the recent decline in Glacier’s stock price, as well as the interest rate effect on the fair valuation of investment securities available for sale and the corresponding recording of the unrealized gain or loss to shareholders’ equity.

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On May 10, 2021, a special meeting of the AB Board was convened. KBW updated the AB Board on its discussion with Glacier and D.A. Davidson about the transaction’s economics. Jones Day addressed the status of the legal documentation for the proposed transaction. The proposed timing and strategy for approaching the Section 13D Group regarding the proposed transaction was also discussed. The Board discussed the overall strength and viability of the proposed transaction, taking into account the fluctuation in the implied valuation as a result of changes in stock prices, and the AB Board instructed executive management of AB to continue to move forward negotiating the potential transaction with the assistance of AB’s external advisors. The AB Board also authorized executive management and the advisors of AB to contact Davis Partnership, L.P., Davis Capital Partners, LLC and Lansing Davis (collectively, the “Davis Group”) and representatives for the Section 13D Group in connection with the potential transaction.

Also on May 10, 2021, Mr. Williams approached the Davis Group regarding execution of a customary non-disclosure agreement to facilitate discussion about the potential transaction and garnering the group’s support for the same through execution of a voting agreement.

On May 11, 2021, the Davis Group entered into a non-disclosure agreement.

On or about May 11, 2021, as directed by the AB Board, KBW and Jones Day approached the investment banker and legal counsel, respectively, for the Section 13D Group regarding execution of a customary non-disclosure agreement to facilitate discussion about the potential transaction and garnering the group’s support for the same through execution of a voting agreement.

On May 12, 2021, the Section 13D Group entered into a non-disclosure agreement with AB, after which KBW and Jones Day discussed with the Section 13D Group’s advisors the general terms of the proposed transaction and the request for execution of a voting agreement. During the period from May 12, 2021 to May 17, 2021, legal counsel to the Section 13D Group, Miller Nash, Jones Day, and executive management of AB negotiated and exchanged drafts of the voting agreement.

Also on May 12, 2021, Mr. Williams discussed the potential transaction and the voting agreement with the Davis Group. During the period between May 12, 2021 and May 17, 2021, legal counsel to the Davis Group, Miller Nash, Jones Day and management of AB negotiated and exchanged drafts of the voting agreement.

Also on May 12, 2021, certain executive officers of AB were presented with draft employment agreements to be entered into in connection with the signing of the merger agreement. During the period from May 12, 2021 to May 16, 2021, Miller Nash and certain executive officers of AB and their independent counsel negotiated and exchanged drafts of the employment agreements.

On May 17, 2021, at the Section 13D Group’s request, Mr. Chesler, Craig A. Langel, chair of Glacier’s Board of Directors, Ronald J. Copher, Executive Vice President and Chief Financial Officer of Glacier, and Donald J. Chery, Executive Vice President and Chief Administrative Officer of Glacier, met with representatives of the Section 13D Group to discuss the proposed transaction.

Also on May 17, 2021, a special meeting of the AB Board was convened to consider the proposed merger transaction. Members of executive management and representatives of KBW and Jones Day attended the meeting at the invitation of the AB Board. The AB Board was provided with a set of meeting materials in advance of the meeting, including substantially final drafts of the merger agreement, the voting agreements which included key members of the Section 13D Group and the Davis Group, the non-competition/non-solicitation agreements, and a summary of the material terms of the merger agreement prepared by Jones Day. Jones Day discussed with the directors their fiduciary duties under applicable law and reviewed the accompanying legal standards. Jones Day proceeded to review in detail with the AB Board the terms of the merger agreement, including the terms of various ancillary documents. KBW then reviewed the financial aspects of the proposed transaction, including the financial analyses with respect to the proposed transaction that KBW performed, and KBW rendered to the AB Board an opinion, initially rendered verbally and confirmed in a written opinion dated May 17, 2021, to the effect

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that, as of such date and subject to the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW as set forth in its opinion, the exchange ratio in the proposed merger was fair, from a financial point of view, to the holders of AB common shares. The AB Board considered the values of the other acquisition proposals that had been previously received, taking into account changes in stock prices, and noted that the consideration in the proposed transaction with Glacier was still clearly the best for shareholders.

After considering the proposed terms of the merger agreement and related transaction documents, and taking into consideration the matters discussed during that meeting and prior meetings of the AB Board, including the strategic options discussed at those meetings and the factors described under the section of this proxy statement/prospectus entitled “Recommendation of the AB Board and Reasons for the Merger,” the AB Board determined that the merger was fair to and in the best interests of AB and AB shareholders, and the AB Board unanimously approved, adopted and declared advisable the execution, delivery and performance of the merger agreement and the transactions contemplated by it, including the merger, and recommended to AB’s shareholders that they approve the merger and the merger agreement.

AB executive management then discussed with the AB Board the proposed communication plan, including the public announcement, internal meeting with employees, and schedule for media and investor calls.

On May 18, 2021, a special meeting of the Glacier Board was convened to consider the proposed merger transaction. Members of executive and senior management and representatives of D.A. Davidson and Miller Nash also attended the meeting at the invitation of the Glacier Board. The Glacier Board was provided with a set of meeting materials in advance of the meeting, including substantially final drafts of the merger agreement, the voting agreements, the non-competition/non-solicitation agreements, and a comprehensive due diligence review summary. Miller Nash discussed with the directors their fiduciary duties under applicable law and reviewed the accompanying legal standards. Members of Glacier’s executive and senior management team then reviewed the enhanced due diligence process in detail. This included a review of the credit, compliance and legal findings. D.A. Davidson then reviewed the financial aspects of the proposed transaction, including the financial analyses with respect to the proposed transaction that D.A. Davidson performed. Miller Nash proceeded to review in detail with the Glacier Board the terms of the merger agreement, including the terms of various ancillary documents. After considering the proposed terms of the merger agreement and related transaction documents, and taking into consideration the matters discussed during that meeting and prior meetings of the Glacier Board, the Glacier Board determined that the merger was in the best interests of Glacier and Glacier shareholders, and the Glacier Board unanimously approved, adopted and declared advisable the execution, delivery and performance of the merger agreement and the transactions contemplated by it, including the merger.

Following receipt of approval of the merger agreement and transaction from the Glacier Board on May 18, 2021, AB and Glacier executed the merger agreement, each of the directors and each of the executive officers of AB, the Davis Group and members of the Section 13D Group executed the voting agreements with Glacier, each of the directors of AB executed the non-solicitation/non-competition agreements with Glacier, and certain executive officers of AB executed their employment agreements with Glacier. On the afternoon of May 18, 2021, each of Glacier and AB issued press releases announcing the execution of the merger agreement.

On May 19, 2021, Glacier and AB each made a customary filing with the SEC on Form 8-K regarding the execution of the merger agreement and included a copy of the merger agreement as an exhibit to such filing.

Recommendation of the AB Board and Reasons for the Merger

After careful consideration, at a meeting held on May 17, 2021, the AB Board determined that the merger agreement, including the merger of the Bank into Glacier Bank, is in the best interests of AB and AB’s shareholders and approved and adopted the merger agreement.

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In reaching its decision to approve the merger agreement, the merger and the other transactions contemplated by the merger agreement and to recommend that the AB shareholders vote “FOR” the proposal to approve the merger agreement, the AB Board evaluated the merger agreement, the merger, and the other transactions contemplated by the merger agreement in consultation with AB’s executive management, as well as AB’s financial advisor, KBW, and legal advisor, Jones Day, and considered various factors, including, without limitation, the following material factors:

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The AB Board also considered a number of potential risks and uncertainties associated with the mergers in connection with its deliberation of the proposed transaction, including, without limitation, the following:

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The foregoing discussion of the information and factors considered by the AB Board is not intended to be exhaustive, but, rather, includes the material factors considered by the AB Board. In reaching its decision to approve the merger agreement, the merger of the Bank into Glacier Bank and the other transactions contemplated by the merger agreement, the AB Board did not quantify or assign any relative weights to the factors considered, and individual directors may have given different weights to different factors. The AB Board considered all these factors as a whole and overall considered the factors to be favorable to, and support, its determination to approve the merger agreement.

It should be noted that this explanation of the AB Board’s reasoning and all other information presented in this section is forward-looking in nature and, therefore, should be read in light of the factors discussed under the heading “Cautionary Statement Regarding Forward-Looking Statements.”

Opinion of AB’s Financial Advisor

AB engaged KBW to render financial advisory and investment banking services to AB, including an opinion to the AB Board as to the fairness, from a financial point of view, to the common shareholders of AB of the exchange ratio (referred to elsewhere in this proxy statement/prospectus as the per share stock consideration) in the proposed merger. AB selected KBW because KBW is a nationally recognized investment banking firm with substantial experience in transactions similar to the merger. As part of its investment banking business, KBW is continually engaged in the valuation of financial services businesses and their securities in connection with mergers and acquisitions.

As part of its engagement, representatives of KBW attended the meeting of the AB Board held on May 17, 2021, at which the AB Board evaluated the proposed transaction. At this meeting, KBW reviewed the financial aspects of the proposed merger and rendered to the AB Board an opinion to the effect that, as of such date and subject to the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW as set forth in its opinion, the exchange ratio in the proposed merger was fair, from a financial point of view, to the holders of AB common shares. The AB Board directors approved the merger agreement at this meeting.

The description of the opinion set forth herein is qualified in its entirety by reference to the full text of the opinion, which is attached as Appendix B to this document and is incorporated herein by reference, and describes the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW in preparing the opinion.

KBW’s opinion speaks only as of the date of the opinion. The opinion was for the information of, and was directed to, the AB Board (in its capacity as such) in connection with its consideration of the financial terms of the merger. The opinion addressed only the fairness, from a financial point of view, of the exchange ratio in the merger to the holders of AB common shares. It did not address the underlying business decision of AB to engage in the merger or enter into the merger agreement or constitute a recommendation to the AB Board in connection with the merger, and it does not constitute a recommendation to any holder of AB common shares or any shareholder of any other entity as to how to vote in connection with the merger or any other matter, nor does it constitute a recommendation regarding whether or not any such shareholder should enter into a voting, shareholders’ or affiliates’ agreement with respect to the merger or exercise any dissenters’ or appraisal rights that may be available to such shareholder.

KBW’s opinion was reviewed and approved by KBW’s Fairness Opinion Committee in conformity with its policies and procedures established under the requirements of Rule 5150 of the Financial Industry Regulatory Authority.

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In connection with the opinion, KBW reviewed, analyzed and relied upon material bearing upon the financial and operating condition of AB and Glacier and bearing upon the merger, including, among other things:

KBW’s consideration of financial information and other factors that it deemed appropriate under the circumstances or relevant to its analyses included, among others, the following:

KBW also performed such other studies and analyses as it considered appropriate and took into account its assessment of general economic, market and financial conditions and its experience in other transactions, as well as its experience in securities valuation and knowledge of the banking industry generally. KBW also participated in discussions held by the managements of AB and Glacier regarding the past and current business operations, regulatory relations, financial condition and future prospects of their respective companies and such other matters

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as KBW deemed relevant to its inquiry. In addition, KBW considered the results of the efforts undertaken by AB, with KBW’s assistance, to solicit indications of interest from third parties regarding a potential transaction with AB.

In conducting its review and arriving at its opinion, KBW relied upon and assumed the accuracy and completeness of all of the financial and other information that was provided to it or that was publicly available and KBW did not independently verify the accuracy or completeness of any such information or assume any responsibility or liability for such verification, accuracy or completeness. KBW relied upon the management of AB as to the reasonableness and achievability of the publicly available consensus “street estimates” of AB and the assumed AB long-term growth rates referred to above (and the assumptions and bases therefor), and KBW assumed that all such information was reasonably prepared and represented, or in the case of the AB “street estimates” referred to above that such estimates were consistent with, the best currently available estimates and judgments of AB management and that the forecasts, projections and estimates reflected in such information would be realized in the amounts and in the time periods estimated. KBW further relied, with the consent of AB, upon Glacier management as to the reasonableness and achievability of the publicly available consensus “street estimates” of Glacier, the assumed Glacier long-term growth rates, and the estimates regarding certain pro forma financial effects of the merger on Glacier (including, without limitation, the cost savings and related expenses expected to result or be derived from the merger), all as referred to above (and the assumptions and bases for all such information), and KBW assumed that all such information was reasonably prepared and represented, or in the case of the Glacier “street estimates” referred to above that such estimates were consistent with, the best currently available estimates and judgments of Glacier management and that the forecasts, projections and estimates reflected in such information would be realized in the amounts and in the time periods estimated.

It is understood that the portion of the foregoing financial information of AB and Glacier that was provided to KBW was not prepared with the expectation of public disclosure and that all of the foregoing financial information, including the publicly available consensus “street estimates” of AB and Glacier, was based on numerous variables and assumptions that are inherently uncertain (including, without limitation, factors related to general economic and competitive conditions and, in particular, assumptions regarding the ongoing COVID-19 pandemic) and, accordingly, actual results could vary significantly from those set forth in such information. KBW assumed, based on discussions with the respective managements of AB and Glacier and with the consent of the AB Board, that all such information provided a reasonable basis upon which KBW could form its opinion and KBW expressed no view as to any such information or the assumptions or bases therefor. KBW relied on all such information without independent verification or analysis and did not in any respect assume any responsibility or liability for the accuracy or completeness thereof.

KBW also assumed that there were no material changes in the assets, liabilities, financial condition, results of operations, business or prospects of either AB or Glacier since the date of the last financial statements of each such entity that were made available to KBW. KBW is not an expert in the independent verification of the adequacy of allowances for loan and lease losses and KBW assumed, without independent verification and with AB’s consent, that the aggregate allowances for credit losses for AB and Glacier are adequate to cover such losses. In rendering its opinion, KBW did not make or obtain any evaluations or appraisals or physical inspection of the property, assets or liabilities (contingent or otherwise) of AB or Glacier, the collateral securing any of such assets or liabilities, or the collectability of any such assets, nor did KBW examine any individual loan or credit files, nor did it evaluate the solvency, financial capability or fair value of AB or Glacier under any state or federal laws, including those relating to bankruptcy, insolvency or other matters. Estimates of values of companies and assets do not purport to be appraisals or necessarily reflect the prices at which companies or assets may actually be sold. Such estimates are inherently subject to uncertainty and should not be taken as KBW’s view of the actual value of any companies or assets.

KBW assumed, in all respects material to its analyses:

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KBW assumed that the merger would be consummated in a manner that complies with the applicable provisions of the Securities Act of 1933, as amended, the Exchange Act, and all other applicable federal and state statutes, rules and regulations. KBW was further advised by representatives of AB that AB relied upon advice from its advisors (other than KBW) or other appropriate sources as to all legal, financial reporting, tax, accounting and regulatory matters with respect to AB, Glacier, the merger and any related transactions, and the merger agreement. KBW did not provide advice with respect to any such matters. KBW assumed, at the direction of AB and without independent verification, that the AB Closing Capital (as defined in the merger agreement) would be no less than the Closing Capital Requirement (as defined in the merger agreement). In addition, at the direction of AB, KBW gave no effect to any potential adjustment to the exchange ratio (as provided in the merger agreement) for purposes of the opinion.

KBW’s opinion addressed only the fairness, from a financial point of view, as of the date of the opinion, of the exchange ratio in the merger to the holders of AB common shares, without regard to individual circumstances of specific holders or groups of holders with respect to control, voting or other rights or aspects which may distinguish such holders. KBW expressed no view or opinion as to any other terms or aspects of the merger or any term or aspect of any related transaction (including the bank merger or the actions relating to the ESOP to be undertaken in connection with the merger as provided in the merger agreement), including without limitation, the form or structure of the merger or any such related transaction, any consequences of the merger or any such related transaction to AB, its shareholders, creditors or otherwise, or any terms, aspects, merits or implications of any employment, consulting, voting, support, shareholder or other agreements, arrangements or understandings contemplated or entered into in connection with the merger, any such related transaction, or otherwise. KBW’s opinion was necessarily based upon conditions as they existed and could be evaluated on the date of such opinion and the information made available to KBW through such date. There has been widespread disruption, extraordinary uncertainty and unusual volatility arising from the effects of the COVID-19 pandemic, including the effect of evolving governmental interventions and non-interventions. Developments subsequent to the date of KBW’s opinion may have affected, and may affect, the conclusion reached in KBW’s opinion and KBW did not and does not have an obligation to update, revise or reaffirm its opinion. KBW’s opinion did not address, and KBW expressed no view or opinion with respect to:

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In performing its analyses, KBW made numerous assumptions with respect to industry performance, general business, economic, market and financial conditions and other matters, which are beyond the control of KBW, AB and Glacier. Any estimates contained in the analyses performed by KBW are not necessarily indicative of actual values or future results, which may be significantly more or less favorable than suggested by these analyses. Additionally, estimates of the value of businesses or securities do not purport to be appraisals or to reflect the prices at which such businesses or securities might actually be sold. Accordingly, these analyses and estimates are inherently subject to substantial uncertainty. In addition, KBW’s opinion was among several factors taken into consideration by the AB Board in making its determination to approve the merger agreement and the merger. Consequently, the analyses described below should not be viewed as determinative of the decision of the AB Board with respect to the fairness of the exchange ratio. The type and amount of consideration payable in the merger were determined through negotiation between AB and Glacier and the decision of AB to enter into the merger agreement was solely that of the AB Board.

The following is a summary of the material financial analyses presented by KBW to the AB Board in connection with its opinion. The summary is not a complete description of the financial analyses underlying the opinion or the presentation made by KBW to the AB Board, but summarizes the material analyses performed and presented in connection with such opinion. The financial analyses summarized below include information presented in tabular format. The tables alone do not constitute a complete description of the financial analyses. The preparation of a fairness opinion is a complex analytic process involving various determinations as to appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances. Therefore, a fairness opinion is not readily susceptible to partial analysis or summary description. In arriving at its opinion, KBW did not attribute any particular weight to any analysis or factor that it considered, but rather made qualitative judgments as to the significance and relevance of each analysis and factor. Accordingly, KBW believes that its analyses and the summary of its analyses must be considered as a whole and that selecting portions of its analyses and factors or focusing on the information presented below in tabular format, without considering all analyses and factors or the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of the process underlying its analyses and opinion.

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For purposes of the financial analyses described below, KBW utilized an implied transaction value for the proposed merger of $49.25 per outstanding AB common share, or approximately $937.8 million in the aggregate (inclusive of the implied value of in-the-money AB stock options), based on the 0.7971x exchange ratio in the proposed merger and the closing price of Glacier common stock on May 14, 2021. In addition to the financial analyses described below, KBW reviewed with the AB Board for informational purposes, among other things, implied transaction multiples for the proposed merger (based on the implied transaction value for the merger of $49.25 per outstanding AB common share) of 23.0x AB’s estimated calendar year 2021 earnings per share (“EPS”) using reported financial results for the fiscal quarter ended March 31, 2021 of AB and publicly available consensus “street estimates” of AB for the second, third and fourth fiscal quarters 2021.

AB Selected Companies Analysis. Using publicly available information, KBW compared the financial performance, financial condition and market performance of AB to 11 major exchange-traded banks headquartered in the Western United States (defined as Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming) with total assets between $2.0 billion and $7.0 billion. Merger targets, ethnic-focused banks, savings banks and thrifts were excluded from the selected companies.

The selected companies were as follows:

To perform this analysis, KBW used profitability and other financial information for the most recent completed fiscal quarter (“MRQ”) (or, in the case of dividend yield, most recent completed fiscal quarter annualized) or the latest 12 months (“LTM”) available or as of the end of such periods and market price information as of May 14, 2021. KBW also used 2021 and 2022 EPS estimates for AB taken from publicly available consensus “street estimates” of AB and used 2021 and 2022 EPS earnings estimates for the selected companies taken from publicly available consensus “street estimates” of the selected companies. Where consolidated holding company level financial data for AB and the selected companies was unreported, subsidiary bank level data was utilized to calculate ratios (subsidiary bank level data necessary to calculate Total Capital Ratio was also unreported for one of the selected companies). Certain financial data prepared by KBW, and as referenced in the tables presented below, may not correspond to the data presented in AB’s historical financial statements as a result of the different periods, assumptions and methods used by KBW to compute the financial data presented.

KBW’s analysis showed the following concerning the financial performance of AB and the selected companies:

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KBW’s analysis showed the following concerning the financial condition of AB and, to the extent publicly available, the selected companies:

In addition, KBW’s analysis showed the following concerning the market performance of AB and the selected companies:

The high stock price-to-tangible book value per share multiple, high stock price-to-LTM EPS multiple, high stock price-to-2021 estimated EPS multiple and high stock price-to-2022 estimated EPS multiple of the selected companies were 2.52x, 20.7x, 21.2x and 21.5x, respectively.

No company used as a comparison in the above selected companies analysis is identical to AB. Accordingly, an analysis of these results is not mathematical. Rather, it involves complex considerations and judgments concerning differences in financial and operating characteristics of the companies involved.

Glacier Selected Companies Analysis. Using publicly available information, KBW compared the financial performance, financial condition and market performance of Glacier to nine major exchange-traded U.S. banks headquartered in the Western United States with total assets between $8.0 billion and $30.0 billion. Merger targets, ethnic-focused banks, savings banks and thrifts were excluded from the selected companies.

The selected companies were as follows:

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To perform this analysis, KBW used profitability and other financial information for the most recent completed fiscal quarter (or, in the case of dividend yield, most recent completed fiscal quarter annualized) or the latest 12 months available or as of the end of such periods and market price information as of May 14, 2021. KBW also used 2021 and 2022 EPS estimates for Glacier taken from publicly available consensus “street estimates” of Glacier and used 2021 and 2022 EPS earnings estimates taken from publicly available consensus “street estimates” of the selected companies. Where consolidated holding company level financial data for the selected companies was unreported, subsidiary bank level data was utilized to calculate ratios. Certain financial data prepared by KBW, and as referenced in the tables presented below, may not correspond to the data presented in Glacier’s historical financial statements as a result of the different periods, assumptions and methods used by KBW to compute the financial data presented.

KBW’s analysis showed the following concerning the financial performance of Glacier and the selected companies:

KBW’s analysis also showed the following concerning the financial condition of Glacier and the selected companies:

In addition, KBW’s analysis showed the following concerning the market performance of Glacier and the selected companies (excluding the impact of the LTM EPS multiple for one of the selected companies, which multiple was considered to be not meaningful because it was greater than 30.0x):

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The stock price-to-tangible book value per share multiple, high stock price-to-2021 estimated EPS multiple and high stock price-to-2022 estimated EPS multiple of the selected companies were 2.84x, 17.0x and 18.3x, respectively. Excluding the impact of the LTM EPS multiple for one of the selected companies, which multiple was considered to be not meaningful because it was greater than 30.0x, the high stock price-to-LTM EPS multiple of the selected companies was 20.8x.

No company used as a comparison in the above selected companies analysis is identical to Glacier. Accordingly, an analysis of these results is not mathematical. Rather, it involves complex considerations and judgments concerning differences in financial and operating characteristics of the companies involved.

Selected Transactions Analysis. KBW reviewed publicly available information related to 11 U.S. bank transactions announced since January 1, 2019 with announced deal values between $500 million and $1.5 billion.

The selected transactions were as follows:

For each selected transaction, KBW derived the following implied transaction statistics, in each case based on the transaction consideration value paid for the acquired company and using financial data based on the acquired company’s then latest publicly available financial statements and, to the extent then publicly available, consensus “street estimates” prior to the announcement of the respective transaction:

KBW also reviewed the price per common share paid for the acquired company for the 10 selected transactions involving publicly traded acquired companies as a premium to the closing stock price of the acquired company one day prior to the announcement of the acquisition (expressed as a percentage and referred to as the one-day market premium). The resulting transaction statistics for the selected transactions were compared with the corresponding transaction statistics for the proposed merger based on the implied transaction value for the merger of $49.25 per outstanding AB common share and using historical financial information for AB as of or for the 12 months ended March 31, 2021, publicly available consensus “street estimates” of AB for 2022 and the closing price of AB common shares on May 14, 2021.

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The results of the analysis are set forth in the following table:

The high stock price-to-tangible book value per share multiple, high price-to-LTM EPS multiple and high core deposit premium of the selected transactions were 2.29x, 40.3x and 27.5%, respectively. For the nine selected transactions in which consensus “street estimates” for the acquired company were available at announcement, the high stock price-to-Forward EPS multiple of the selected transactions was 16.7x. For the 10 selected transactions involving publicly traded acquired companies, the high one-day market premium of the selected transactions was 29.5%.

No company or transaction used as a comparison in the above selected transactions analysis is identical to AB or the proposed merger. Accordingly, an analysis of these results is not mathematical. Rather, it involves complex considerations and judgments concerning differences in financial and operating characteristics of the companies involved.

Relative Contribution Analysis. KBW analyzed the relative standalone contribution of Glacier and AB to various pro forma balance sheet and income statement items and the combined market capitalization of the combined entity. This analysis did not include purchase accounting adjustments or cost savings. To perform this analysis, KBW used (i) balance sheet and net income data of Glacier and AB as of, or for the fiscal quarter ended, March 31, 2021, (ii) publicly available consensus “street estimates” of Glacier and AB for the second, third and fourth fiscal quarters 2021 and for 2022, and (iii) market price information as of May 14, 2021. The results of KBW’s analysis are set forth in the following table, which also compares the results of KBW’s analysis with the implied pro forma ownership percentages of Glacier shareholders and AB shareholders in the combined company based on the 0.7971x exchange ratio provided for in the merger agreement:

Financial Impact Analysis. KBW performed a pro forma financial impact analysis that combined projected income statement and balance sheet information of Glacier and AB. Using (i) closing balance sheet estimates as of October 31, 2021 for Glacier and AB taken from publicly available consensus “street estimates,” (ii) net

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income data of Glacier and AB for the fiscal quarter ended March 31, 2021 and publicly available consensus “street estimates” of Glacier and AB for the second, third and fourth fiscal quarters 2021 and for 2022, and (iii) pro forma assumptions (including, without limitation, the cost savings and related expenses expected to result from the merger and certain purchase accounting and other merger-related adjustments and restructuring charges assumed with respect thereto) provided by Glacier management, KBW analyzed the potential financial impact of the merger on certain projected financial results of Glacier. This analysis indicated the merger could be accretive to Glacier’s estimated 2022 EPS by 5.3% and accretive to Glacier’s estimated tangible book value per share at closing as of October 31, 2021 by 0.9%. Furthermore, the analysis indicated that, pro forma for the merger, each of Glacier’s tangible common equity to tangible assets ratio and Common Equity Tier 1 Ratio at closing as of October 31, 2021 could be lower by 9 and 1 basis points, respectively, and each of Glacier’s Leverage Ratio, Tier 1 Capital Ratio and Total Risk-Based Capital Ratio at closing as of October 31, 2021 could be higher by 38, 38 and 27 basis points, respectively. For all of the above analysis, the actual results achieved by Glacier following the merger may vary from the projected results, and the variations may be material.

AB Dividend Discount Model Analysis. KBW performed a dividend discount model analysis of AB to estimate a range for the implied equity value of AB. In this analysis, KBW used publicly available consensus “street estimates” for AB and assumed long-term growth rates for AB provided by AB management, and assumed discount rates ranging from 11.0% to 15.0%. The range of values was derived by adding (i) the present value of implied future excess capital available for dividends that AB could generate over the period from March 31, 2021 through December 31, 2025 as a standalone company, and (ii) the present value of AB’s implied terminal value at the end of such period. KBW assumed that AB would maintain a tangible common equity to tangible assets ratio of 8.00% and would retain sufficient earnings to maintain that level. In calculating implied terminal values for AB, KBW applied a range of 12.5x to 16.5x to AB’s estimated 2026 earnings. This dividend discount model analysis resulted in a range of implied values per AB common share of $28.99 to $40.88.

The dividend discount model analysis is a widely used valuation methodology, but the results of such methodology are highly dependent on the assumptions that must be made, including asset and earnings growth rates, terminal values and discount rates. The foregoing dividend discount model analysis did not purport to be indicative of the actual values or expected values of AB.

Glacier Dividend Discount Model Analysis. KBW performed a dividend discount model analysis of Glacier to estimate a range for the implied equity value of Glacier. In this analysis, KBW used publicly available consensus “street estimates” for Glacier and assumed long-term growth rates for Glacier provided by Glacier management, and assumed discount rates ranging from 9.0% to 13.0%. The range of values was derived by adding (i) the present value of implied future excess capital available for dividends that Glacier could generate over the period from March 31, 2021 through December 31, 2025 as a standalone company, and (ii) the present value of Glacier’s implied terminal value at the end of such period. KBW assumed that Glacier would maintain a tangible common equity to tangible assets ratio of 8.00% and would retain sufficient earnings to maintain that level. In calculating implied terminal values for Glacier, KBW applied a range of 17.0x to 21.0x to Glacier’s estimated 2026 earnings. This dividend discount model analysis resulted in a range of implied values per share of Glacier common stock of $40.70 to $55.69.

The dividend discount model analysis is a widely used valuation methodology, but the results of such methodology are highly dependent on the assumptions that must be made, including asset and earnings growth rates, terminal values and discount rates. The foregoing dividend discount model analysis did not purport to be indicative of the actual values or expected values of Glacier or the pro forma combined entity.

Pro Forma Combined Dividend Discount Model Analysis. KBW performed a dividend discount model analysis to estimate a range for the implied equity value of the pro forma combined entity. In this analysis, KBW used publicly available consensus “street estimates” for Glacier and AB, assumed Glacier and AB long-term growth rates provided by Glacier management and AB management, respectively, and pro forma assumptions (including, without limitation, the cost savings and related expenses expected to result from the merger and

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certain purchase accounting and other merger-related adjustments and restructuring charges assumed with respect thereto) provided by Glacier management, and KBW assumed discount rates ranging from 9.0% to 13.0. The range of values was derived by adding (i) the present value of implied future excess capital available for dividends that the pro forma combined entity could generate over the period from October 31, 2021 through December 31, 2025 and (ii) the present value of the pro forma combined entity’s implied terminal value at the end of such period, in each case applying the pro forma assumptions. KBW assumed that the pro forma combined entity would maintain a tangible common equity to tangible assets ratio of 8.00% and would retain sufficient earnings to maintain that level. In calculating implied terminal values of the pro forma combined entity, KBW applied a range of 17.0x to 21.0x to the pro forma combined entity’s estimated 2026 earnings. This dividend discount model analysis resulted in an illustrative range of implied values for the 0.7971 of a share of Glacier common stock to be received in the proposed merger for each AB common share of $35.91 to $48.46.

The dividend discount model analysis is a widely used valuation methodology, but the results of such methodology are highly dependent on the assumptions that must be made, including asset and earnings growth rates, terminal values and discount rates. The foregoing dividend discount model analysis did not purport to be indicative of the actual values or expected values of the pro forma combined entity.

Miscellaneous. KBW acted as financial advisor to AB in connection with the proposed merger and did not act as an advisor to or agent of any other person. As part of its investment banking business, KBW is continually engaged in the valuation of bank and bank holding company securities in connection with acquisitions, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements and valuations for various other purposes. As specialists in the securities of banking companies, KBW has experience in, and knowledge of, the valuation of banking enterprises. KBW and its affiliates, in the ordinary course of its and their broker-dealer businesses (and further to existing sales and trading relationships between a KBW broker-dealer affiliate and Glacier), may from time to time purchase securities from, and sell securities to, AB and Glacier. In addition, as a market maker in securities, KBW and its affiliates may from time to time have a long or short position in, and buy or sell, debt or equity securities of AB or Glacier for its and their own respective accounts and for the accounts of its and their respective customers and clients.

Pursuant to the KBW engagement agreement, AB agreed to pay KBW a cash fee equal to 1.075% of the aggregate merger consideration, $1,000,000 of which became payable to KBW with the rendering of KBW’s opinion and the balance of which is contingent upon the closing of the merger. AB also agreed to reimburse KBW for reasonable out-of-pocket expenses and disbursements incurred in connection with its retention and to indemnify KBW against certain liabilities relating to or arising out of KBW’s engagement or KBW’s role in connection therewith. Other than in connection with the present engagement, in the two years preceding the date of its opinion, KBW did not provide investment banking or financial advisory services to AB. In the two years preceding the date of its opinion, KBW provided investment banking and financial advisory services to Glacier and received compensation for such services. KBW acted as (i) financial advisor to Glacier in connection with its acquisition of Heritage Bancorp in July of 2019, and (ii) financial advisor to Glacier in connection with its acquisition of State Bank Corp. in February of 2020. KBW may in the future provide investment banking and financial advisory services to AB or Glacier and receive compensation for such services.

Recommendation of AB Board

For the reasons set forth above, the AB Board approved the merger agreement, including the merger of the Bank into Glacier Bank, and recommends that AB shareholders vote “FOR” the proposal to approve the merger agreement, “FOR” the merger-related named executive officer compensation proposal and “FOR” the adjournment proposal.

In connection with entering into the merger agreement, each member of the AB Board and each executive officer of AB, in their capacities as AB shareholders, have entered into the voting agreements. The voting agreements require, among other things, that the shareholder party thereto vote all of his or her AB common

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shares in favor of the merger and the other transactions contemplated by the merger agreement and against actions that would result in a breach of the merger agreement or prevent, impede, interfere with, delay or frustrate the purposes of the transactions contemplated by the merger agreement, and not sell, transfer encumber or grant a proxy with respect to their AB common shares, subject to certain exceptions. For further information, please see the section entitled “The Merger Agreement—Voting Agreements.”

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