As filed with the Securities and Exchange Commission on December 4, 2017September 27, 2023

RegistrationNo. 333-221588333-274515

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

PRE-EFFECTIVE AMENDMENT NO. 1

TO

FORMS-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

GLACIER BANCORP, INC.

(Exact name of registrant as specified in its charter)

49 Commons Loop, Kalispell, Montana 59901 (406)756-4200

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

RANDALL M. CHESLER

President and Chief Executive Officer

49 Commons Loop

Kalispell, Montana 59901

(406)756-4200

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of communications to:

Approximate date of commencement of proposed sale of securities to the public:

As soon as practicable after this Registration Statement becomes effective and upon completion of the merger described in the enclosed document.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box. ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, a smaller reporting company, or an emerging growth company. See definitionthe definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule12b-2 of the Exchange Act. (Check one):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided purchase to Section 7(a)(2)(B) of the Securities Act. ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

Information contained herein is subject to completion or amendment. A registration statement relating to these securities has been filed with the Securities and Exchange Commission. These securities may not be sold prior to the time the registration statement becomes effective. This document shall not constitute an offer to sell nor shall there be any sale of these securities in any jurisdiction in which such offer or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.

PRELIMINARY—SUBJECT TO COMPLETION—DATED DECEMBER 4, 2017SEPTEMBER 27, 2023

MERGER PROPOSED – YOUR VOTE IS VERY IMPORTANT

Dear Inter-Mountain Bancorp.,Community Financial Group, Inc. Shareholders:

As you may know, the boards of directors of Inter-Mountain Bancorp.,Community Financial Group, Inc. (“IMB”CFGW”) and Glacier Bancorp, Inc., Kalispell, Montana (“Glacier”) have each unanimously approved a merger of IMBCFGW with and into Glacier, subject to approval by IMBCFGW shareholders and appropriate bank regulators. Immediately following the merger, IMB’sCFGW’s subsidiary First SecurityWheatland Bank (“FSB”(the “Bank”) will be merged into Glacier’s subsidiary Glacier Bank (“Glacier Bank”), subject to approval of the appropriate bank regulators.

Under the terms of the Plan and Agreement of Merger, dated October 26, 2017August 8, 2023 (the “merger agreement”), each outstanding CFGW common share as of IMB common stockthe effective time will be exchanged for 22.8411.0931 shares of Glacier common stock (the “per share stock consideration”), subject to certain adjustments.adjustments, with cash paid in lieu of fractional shares. The common stock of Glacier trades on The New York Stock Exchange under the symbol “GBCI.” CFGW’s common stock is currently quoted on the OTC Markets under the symbol “CFGW.”

The amount of Glacier commonper share stock exchanged for each share of IMB common stockconsideration is subject to adjustment in the event that the averageif CFGW’s closing price for Glacier common stock prior to closing, calculatedcapital, after being adjusted in accordance with the terms of the merger agreement, is less than $28.07 or more than $42.11, and IMB or Glacier provides notice$49,200,000 (subject to terminatespecified adjustments). In any such event, the merger agreement, and Glacier or IMB, asper share stock consideration will be reduced on a per share basis in accordance with the case may be, elects to adjust the number of shares on aper-share basis to be issuedformula set forth in the merger (or, with respect to Glacier, elects to pay additional cash consideration as described in this proxy statement/prospectus) in order to avoid such termination.agreement. See “The Merger – Merger Consideration.”

The merger agreement establishes a minimum requirement for IMB’s capital ($73,500,000) prior to the closing of the merger. If IMB’sCFGW’s closing capital, asafter being adjusted in accordance with the terms of the merger agreement, is in excess of $49,200,000, CFGW may, prior to the minimum required, IMB may in its sole discretionclosing of the merger, pay a special cash dividend to its shareholders in the amount of such excess. For purposes of illustration only, as of October 31, 2017, IMB’s closing capital would have been approximately $75.3 million, resulting in a special dividend available to IMB’s shareholders of approximately $1.8 million in the aggregate or approximately $8.70 per share. Accordingly, based on the above, it is presently anticipated that a special cash dividend will be paid immediately prior to closing.See “The Merger – Merger Consideration.”

Assuming for purposes of illustration only that the average closing price for Glacier common stock is $40.05,$28.77, which was the closing price of Glacier common stock on November 30, 2017September 25, 2023, as quoted on the NASDAQ Global Select Market,The New York Stock Exchange, for each of your shares of IMBCFGW common stock,shares, you will receive 22.841 Glacier sharesconsideration with an estimated current value of $914.78. Trading in IMB$31.45, consisting of 1.0931 shares of Glacier common stock occurs very infrequently and is restricted by agreement. During 2017, IMB is aware of two transactions in its common stock, each of which was valued at $480.76 per share.stock.

Assuming the exchange ofthat all outstanding IMBCFGW common stockshares are exchanged for Glacier common stock in accordance with the merger agreement IMBand the per share stock consideration is not adjusted as described above, CFGW shareholders will, in the aggregate, ownreceive approximately 5.51%2,429,950 shares of Glacier common stock in the merger, representing approximately 2.14% of Glacier’s outstanding common stock followingafter taking into account Glacier shares to be issued in the merger.

IMBCFGW will hold a special shareholders’ meeting to vote on the merger agreement.The special meeting of the shareholders of IMB will be heldagreement on January 16, 2018November 14, 2023, at 1:3:00 p.m. MountainPacific Time at 222 North Wall Street, Lower Level Conference Room, Spokane, Washington 99201. Detailed instructions for participation can be found in the Community Roomnotice of the First Security Bank branch located at 670 19^th Avenue, Bozeman, Montana59715.special shareholder meeting that accompanies this proxy statement/prospectus. Whether or not you plan to attendparticipate in the special meeting, please take the time to vote by voting over the Internet, by telephone or completing and mailing the enclosed form of proxy.Please give particular attention to the discussion under the heading “Risk Factors” beginning on page 13 for risk factors relating to the merger that you should consider.

The board of directors of IMBCFGW has unanimously recommended that you vote FOR approval of the merger agreement and the other proposals described in this proxy statement/prospectus.

Neither the Federal Deposit Insurance Corporation, Securities and Exchange Commission, nor any state securities commission has approved the securities to be issued by Glacier or determined if this proxy statement/prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The shares of Glacier common stock to be issued in the merger are not savings or deposit accounts or other obligations of a bank and are not insured by the Federal Deposit Insurance Corporation, the Federal Deposit Insurance Fund or any other governmental agency. Such shares are not guaranteed by Glacier or IMBCFGW and are subject to investment risk, including the possible loss of principal.

This proxy statement/prospectus is dated December 4, 2017October  , 2023, and is first being mailed to

IMB CFGW shareholders on or about December 7, 2017.October 9, 2023.

INTER-MOUNTAIN BANCORP., INC.222 North Wall Street, Suite 300, Spokane, Washington 99201

208 East Main Street

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS OF

COMMUNITY FINANCIAL GROUP, INC.

TO BE HELD January 16, 2018ON NOVEMBER 14, 2023

TO THE SHAREHOLDERS OF INTER-MOUNTAIN BANCORP., INC.

To the Shareholders of Community Financial Group, Inc.:

A special meeting of the shareholders of Inter-Mountain Bancorp.,Community Financial Group, Inc. (“IMB”CFGW”) will be held onJanuary 16, 2018 November 14, 2023 at1: 3:00 p.m.Mountain Pacific Time,in theCommunity at 222 North Wall Street, Lower Level Conference Room, of the First Security Bank branch located at 670 19^th Avenue,Bozeman, Montana59715.TheSpokane, Washington 99201. The special meeting is for the following purposes:

Holders of record of IMBCFGW common stockshares at the close of business on December 1, 2017,September 27, 2023, the record date for the special meeting, are entitled to notice of and to vote at the special meeting or any adjournments or postponements of it. The affirmative vote of the holders of at leasttwo-thirds (66 2/3%) a majority of the outstanding shares of IMB’s outstandingCFGW’s common stock entitled to vote is required for approval of the merger agreement. To that end, IMB’sCFGW’s directors and certain IMB shareholdersof CFGW’s executive officers have signed agreements to vote their shares in favor of the merger agreement. SuchAs of the record date, to CFGW’s knowledge, such persons arewere entitled to vote 120,530612,869 shares representing approximately 59.15%28.7% of all outstanding shares of IMBCFGW common stock.shares. As of December 1, 2017,the record date, there were 203,7632,136,808 CFGW common shares of IMB common stock outstanding.

IMB shareholders have the right to dissent from the merger and obtain payment of the fair valueof their shares of IMB common stock under the Montana Code Annotated, Sections35-1-826 through35-1-839. A copy of the provisions regarding dissenters’ rights is attached asAppendix B to the accompanying proxy statement/prospectus. For details of your dissenters’ rights and how to exercise them, please see the discussion under “The Merger – Dissenters’ Rights of Appraisal.”

Your vote is important. Whether or not you plan to attend the special meeting, please complete, sign, datewe encourage you to submit a proxy to vote your shares as promptly as possible in order to make certain that you are represented at the meeting. You may submit a proxy over the Internet, as well as by telephone or by completing, signing, dating and promptly returnreturning the accompanying proxy using the enclosed envelope. If for any reason you should desire to revoke your proxy, you may do so at any time before it is voted at the meeting.If you do not vote your shares, it will have the same effect as voting against the merger.

The board of directors of IMBCFGW has determined that the merger agreement is fair to, advisable, and in the best interests of IMBCFGW and its shareholders and unanimously recommends that you vote FOR approval of the merger agreement.agreement and FOR approval of the adjournment proposal. With regard to its recommendation that shareholders vote FOR approval of the merger agreement, the board of directors of IMBCFGW considered a number of factors, including the receipt of a fairness opinion from the investment banking firm of ProBank Austin, as discussed in “Background of and Reasons for the Merger”Merger” beginning on page 19.25. Such factors also constituted the reasons that the board of directors determined to approve the merger agreement and to recommend that IMBCFGW shareholders vote in favor of the merger agreement.

You will receive instructions on how to exchange your sharesImportant Notice Regarding the Availability of IMB common stockProxy Materials for the merger consideration promptly after the closing

Special Shareholders’ Meeting to be held November 14, 2023:

The proxy statement and notice of the merger.special meeting are available at www.proxyvote.com.

REFERENCES TO ADDITIONAL INFORMATION

December 4, 2017

WHERE YOU CAN FIND MORE INFORMATION ABOUT GLACIERGlacier

This proxy statement/prospectus incorporates important business and financial information about Glacier from documents that wereGlacier has previously filed with the SEC that are not included in or delivered with this document. See “Documents Incorporated by Reference” elsewhere in this document.

Glacier files annual, quarterly and current reports, proxy statements, and other information with the Securities and Exchange Commission (“SEC”). You may read and copy any reports, statements,that are contained in or other information that Glacier files with the SEC at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at1-800-SEC-0330 for further information on the operation of the Public Reference Room. Glacier’s SEC filings are also available to the public on the SEC site (http://www.sec.gov). As described below, you may also obtain the documents that Glacier is incorporatingincorporated by reference into this proxy statement/prospectus from Glacier.

Glacier has filedprospectus. For a Registration Statement on FormS-4 to register with the SEC the shareslisting of Glacier common stock to be issued to IMB shareholders in the merger. This proxy statement/prospectus is part of that Registration Statement and constitutes a prospectus of Glacier in addition to being a proxy statement of IMB for its special shareholders meeting. As allowed by SEC rules, this proxy statement/prospectus does not contain all of the information that you can find in the Registration Statement or the exhibits to the Registration Statement.

You can obtain the documents that are incorporated by reference into this proxy statement/prospectus, through Glacier orplease see the SEC.section entitled “Where You can obtainCan Find More Information.” This information is available for you to review at the SEC’s website at http://www.sec.gov.

You may request copies of this proxy statement/prospectus and any of the documents from the SEC, as described above. These documents are also available fromincorporated by reference into this proxy statement/prospectus or other information concerning Glacier, without charge, excluding exhibits unless Glacier has specifically incorporated such exhibits by reference in this proxy statement/prospectus, by requesting them in writing or by telephone from Glacier at the following address:or written request directed to:

Glacier Bancorp, Inc.

49 Commons Loop

Kalispell, Montana 59901

ATTN: Ron Copher, Corporate Secretary

Telephone: (406)751-7706

Certain reportsReports that Glacier files with the SEC and certain other documents can also be found on Glacier’s website atwww.glacierbancorp.com.

Glacier’s common stock is traded on The New York Stock Exchange under the symbol “GBCI.”

You will not be charged for the documents that you request.If you would like to request documents, please do so by January 5, 2018November 7, 2023, in order to receive them before the IMBCFGW special shareholders’ meeting.

Glacier’s common stockCommunity Financial Group, Inc.

CFGW does not have a class of securities registered under Section 12 of the Securities Exchange Act of 1934 (the “Exchange Act”), is traded onnot subject to the NASDAQ Global Select Market underreporting requirements of Section 13(a) or 15(d) of the symbol “GBCI.”

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS

Why am I receiving these materials?

We are sending you these materials to solicit your proxy to vote in favor of the merger and to help you decide how to vote your shares of Inter-Mountain Bancorp.,Community Financial Group, Inc. (“IMB”CFGW”) common stock with respect to its proposed merger with Glacier Bancorp, Inc. (“Glacier”). The merger cannot be completed unless IMBCFGW receives the affirmative vote of the holders of at leasttwo-thirds (66 2/3%) a majority of the outstanding shares of IMB’sCFGW’s common stock. IMBstock entitled to vote on the matter. CFGW is holding a special meeting of shareholders to vote on proposals relating to the merger. Information about the special meeting is contained in this document. See “IMB“CFGW Special ShareholdersShareholders’ Meeting.”

This document is both a proxy statement of IMBCFGW and a prospectus of Glacier. It is a proxy statement because the officers and board of directors of IMBCFGW (the “IMB“CFGW Board”) are soliciting proxies from IMBCFGW’s shareholders in connection with voting on the merger. It is a prospectus because Glacier will issue, and you will acquire in exchange for your CFGW common stock, shares of itsGlacier’s common stock in exchange for CFGW common shares of IMB common stock as the consideration to be paid in the merger.

What will IMBhappen in the merger?

In the proposed merger, CFGW will merge with and into Glacier, with Glacier surviving the merger. Immediately following the merger, Wheatland Bank (the “Bank”) will be merged into Glacier’s subsidiary Glacier Bank. Shares of Glacier will continue to trade on The New York Stock Exchange, with the trading symbol “GBCI.”

What will CFGW shareholders receive in the merger?

Under the terms of the merger agreement, each share of IMBCFGW common stockshare will be exchanged for 22.8411.0931 shares of Glacier common stock (the “per share stock consideration”), subject to adjustment as described below. certain adjustments, with cash paid in lieu of fractional shares.

Assuming for purposes of illustration only that the exchange of all outstanding IMB common stockaverage closing price for Glacier common stock is $28.77 (which was the closing price of Glacier common stock on September 25, 2023), each CFGW common share would be exchanged for 1.0931 shares of Glacier common stock with a value equal to $31.45.

The per share stock consideration will be subject to reduction if the “CFGW Closing Capital,” as defined and determined in accordance with the merger agreement, IMB shareholdersis less than $49,200,000, subject to certain adjustments. In such event, the number of shares of Glacier common stock to be issued will own,be reduced on a per-share basis in accordance with the formula set forth in the aggregate, approximately 5.51% of Glacier’s outstanding common stock following the merger.merger agreement. See “The Merger – Merger Consideration.”

If the IMBCFGW Closing Capital (as defined in the merger agreement) exceeds $73,500,000,$49,200,000, subject to certain adjustments, IMBCFGW may, upon written notice to Glacier and effective immediately prior to the closing of the merger, declare and pay a special dividend to its shareholders in the amount of such excess.

The amountAssuming that all outstanding CFGW common shares are exchanged for Glacier common stock as per share stock consideration in accordance with the merger agreement and the per share stock consideration is not adjusted as described above, CFGW shareholders will receive an estimated 2,429,950 shares of Glacier common stock exchanged for each share of IMB common stock may be adjusted in certain circumstances based on whether Glacier common stock is trading either higher or lower than prices specified in the merger, agreement immediately prior to the closing of the merger, in order to avoid termination of the merger agreement.

On November 30, 2017, the closing pricerepresenting approximately 2.14% of Glacier’s outstanding common stock was $40.05 per share. If the “average closing price” (determined over a 20 trading day period prior to the closing of the merger, calculated 10 days prior to the closing) of Glacier’s common stock exceeds $42.11,after taking into account Glacier may terminate the merger agreement, unless IMB elects to accept a reduction on aper-share basis of the number of shares of Glacier common stock to be issued in the merger.

Conversely, ifHow are outstanding CFGW stock options addressed in the “average closing price” is less than $28.07, IMB may terminatemerger agreement?

Under the terms of the merger agreement, unlesswhen the merger agreement becomes effective (the “effective time”), each outstanding option to purchase CFGW common shares (the “CFGW Options”) under CFGW’s

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Incentive Stock Option Plan of 2018, Non-Qualified Stock Option Plan of 2018, Incentive Stock Option Plan of 2005, and Non-Qualified Stock Option Plan of 2005 (the “CFGW Stock Plans”) will be automatically canceled at the effective time, and the holders of CFGW Options will be paid in cash an amount per share equal to the spread, if any, between (a) the product of the average of the closing sales prices of one share of Glacier electscommon stock on The New York Stock Exchange for the 20 trading days ending on the tenth business day immediately preceding the effective date of the merger (the “Glacier average closing price”) multiplied by the per share stock consideration and (b) the exercise price per share of such CFGW Option, net of any cash which must be withheld under applicable tax laws. Any CFGW Option that has an exercise price per share that is equal to increase on aper-share basisor greater than the number ofamount described in (a) above will be cancelled without any payment.

Will I receive any fractional shares of Glacier common stock to be issued inas part of the merger or in Glacier’s discretion,consideration?

No. Glacier pays cash, or a combination of cash and additional Glacier shares, so that the value of the consideration equals an amount specified in the merger agreement. See “The Merger – Termination of the Merger Agreement.”

By voting to approve the merger agreement, IMB shareholders will give the IMB Board the authority to elect to cause IMB to accept a reduction on aper-share basis of the number ofnot issue any fractional shares of Glacier common stock to be issued in the merger ifmerger. Instead, Glacier will pay you the cash value of a fractional share (without interest) in an amount determined by multiplying the fractional share interest to which you would otherwise be entitled by the Glacier average closing price exceeds $42.11 as described above. See “The Merger – Termination of the Merger Agreement.”

What will I receive in the merger?

Each outstanding share of IMB common stock you own will be exchanged for 22.841 shares of Glacier common stock, subject to adjustment as described above.

Assuming for purposes of illustration only that the average closing price for Glacier common stock is $40.05 (which was the closing price for Glacier common stock on November 30, 2017), each share of IMB common stock would be exchanged for consideration with a total value equal to $914.78.price.

How soon after the merger is completed can I expect to receive my merger consideration?

Glacier will work with its exchange agent, American Stock Transfer & Trust Company, LLC, to distributecomplete the exchange of your CFGW stock certificates for consideration payable in the merger as promptly as practicable following the completion of the merger.

Will I be able to trade the shares of Glacier common stock that I receive in the merger bemerger?

You may freely transferable?

Yes. Thetrade the shares of Glacier common stock issued in the merger, will be transferable freeunless you are an “affiliate” of restrictionsGlacier as defined by Rule 144 under federalthe Securities Act of 1933, as amended. Affiliates consist of individuals or entities that control, are controlled by or are under common control with Glacier, and state securities laws.include the executive officers and directors of Glacier after the merger and may include significant shareholders of Glacier.

When will the merger occur?

We presently expect to complete the merger during the firstfourth quarter of 2018.2023. The actual timing of the transaction is subject to a number of factors (primarily regulatory approvals), many of which are beyond the control of Glacier and IMB.CFGW. The merger is also conditioned upon and will occur after the approval of the merger agreement by the affirmative vote of holders of at leasttwo-thirds (66 2/3%) a majority of the outstanding CFGW common shares of IMB common stock,entitled to vote on the matter at the CFGW special meeting, after the merger has received all required regulatory approvals, and following the satisfaction or waiver of the other conditions to the merger described in the merger agreement and summarizesummarized under “The Merger” below.

The merger agreement provides that the merger will be completed effective as of the last day of the month occurring at least five business days after the fulfillment or waiver of each condition to the merger and receipt of all required approvals; provided that Glacier will not be required to consummate the merger on December 31, 2023 or on January 31, 2024.

If the merger does not occur by JulyMay 31, 2018,2024, either Glacier or IMBCFGW may unilaterally terminate the merger agreement. However,agreement; provided, however, if as of JulyMay 31, 2018, the condition to closing that2024, all required governmental regulatory approvals have been obtained has not been satisfied,obtained, then the deadline for closingconsummation of the merger will be extended to on or before OctoberAugust 31, 2018,2024, if either Glacier or CFGW notifies IMBthe other party in writing on or prior to JulyMay 31, 20182024, of its election to extend such closing deadline.date.

When and where will the special meeting take place?

IMBCFGW will hold a special meeting of its shareholders on January 16, 2018November 14, 2023, at 1:3:00 p.m. MountainPacific Time in the Communityat 222 North Wall Street, Lower Level Conference Room, of the First Security Bank branch located at 670 19^th Avenue, Bozeman, Montana 59715.Spokane, Washington 99201.

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Who may vote at the special meeting?

The IMBCFGW Board has set December 1, 2017September 27, 2023 as the record date for the special meeting. If you were the owner of IMBCFGW common stockshares at the close of business on December 1, 2017,September 27, 2023, you may vote at the special meeting.

What if I fail to submit a proxy or to instruct my broker, bank or other nominee?

If you fail to properly submit a proxy or to instruct your broker, bank or other nominee to vote your CFGW common shares, and you do not attend the special meeting and vote your shares in person, your shares will not be voted. This will have the same effect as a vote “AGAINST” approval of the merger agreement, but will have no impact on the outcome of the other proposals.

Can I change my vote after I have mailedsubmitted my signed proxy card?proxy?

Yes. YouIf you do not hold your shares in “street name,” there are three ways you may change your vote at any time after you have submitted your proxy and before your proxy is voted at the special meeting. If your shares of IMB common stock are held in your own name, you may change your vote as follows:meeting:

If you choose either the first or second method above, you must submit youra written notice of revocation, or your new proxy card to IMB’sit must be received by CFGW’s Secretary prior to the vote at the special meeting.

Following review of this proxy statement/prospectus,please complete, sign,submit a proxy through the Internet, by telephone or by completing, signing, and datedating the enclosed proxy card and returnreturning it in the enclosed envelopeas soon as possible so that your shares of IMBCFGW common stockshares can be voted at IMB’sCFGW’s special meeting of shareholders.

What happens if I sell my shares after the record date but before the special meeting?

The record date of the special meeting is earlier than the date of the special meeting and the date that the merger is expected to be completed. If you sell or otherwise transfer your shares after the record date, but before the date of the special meeting, you will retain your right to vote at the special meeting, but you will not have the right to receive the merger consideration to be received by shareholders in the merger. In order to receive the merger consideration, a shareholder must hold his or her shares through completion of the merger.

What do I do if I receive more than one proxy statement/prospectus or set of voting instructions?

If you hold shares directly as a record holder and also in “street name” or otherwise through a nominee, you may receive more than one proxy statement/prospectus and/or set of voting instructions relating to the special meeting. These should each be voted and/or returned separately in order to ensure that all of your shares are voted.

Should I send in my common stock certificates now?

No.No. Please do not send your IMBCFGW common stockshare certificates with your proxy card.card. You will receive written instructions from Glacier’s exchange agent promptly following the closing of the merger on how to exchange your IMBCFGW common stockshare certificates for the merger consideration. In the meantime, you may wish to begin collecting any certificates in your possession.

What risks should I consider?consider in deciding whether to vote for approval of the merger agreement?

You should review carefully our discussion under “Risk Factors.” You should also review the factors considered by the IMBCFGW Board in approving the merger agreement. See “Background of and Reasons for the Merger.”

What are the material United States federal income tax consequences of the merger to me?CFGW shareholders?

Glacier and IMB expect to reportCFGW intend for the merger of IMB with and into Glacier andto qualify as a “reorganization” within the mergermeaning of FSB with and into Glacier Bank as one or moretax-free reorganizations for U.S. federal income tax purposes under Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). In connection withIf the filingmerger qualifies as a reorganization within the meaning of Section 368(a) of the registration statementInternal Revenue Code, then for U.S. federal income tax purposes a U.S. holder of which this document is a part, Garlington, Lohn & Robinson PLLP, special tax counselCFGW common shares (as defined below) generally will not recognize any gain or loss upon surrendering its CFGW common shares, except with respect to Glacier, has delivered an opinion to Glacier that the mergers will qualify as one or more reorganizations under Section 368(a).

In atax-free reorganization, a shareholder who exchanges his, her or its shares of common stock in an acquired company for shares of common stock in an acquiring company must generally recognize gain (but not loss) on the exchange in an amount equal to the lesser of (1) the amount of gain realized (i.e., the excess of the sum of the fair market value of the shares of the acquiring company common stock

(including any fractional shares) and any cash received pursuant toor treated as received in the merger (excludingand any cash received in lieu of fractional shares) over the shareholder’s adjusted tax basisshares. A U.S. holder of CFGW common shares receiving cash in his, her or its shareslieu of acquired companya fractional share of Glacier common stock surrendered pursuantwill generally recognize gain or loss equal to the merger), or (2)difference between the amount of any cash (excluding any cash received instead of a fractional share and the basis in lieuits fractional share of fractional shares) received pursuantGlacier common stock. The U.S. federal income tax consequences described above may not apply to all holders of CFGW common shares. Your tax consequences will depend on your individual situation. Accordingly, we strongly urge you to consult an independent tax advisor for a full understanding of the merger.

particular tax consequences of the merger to you. For a detailed discussion of the material U.S. federal income tax consequences of the merger, see “The Merger – Material U.S. Federal Income Tax Consequences of the Merger.Merger to CFGW Shareholders.”

We urge you to consult your tax advisor to fully understand the tax consequences to you of the merger. Tax matters are very complicated and in many cases the tax consequences of the merger will depend upon your particular facts and circumstances.

If I do not agree with the merger, do5

Do I have appraisal or dissenters’ rights?

Yes. If you are an IMBa CFGW shareholder and you do not agree with the merger, do not vote in favor of the merger agreement, and take certain other actions required by MontanaWashington law, you will have dissenters’ rights under Sections 23B.13.010 through 23B.13.310 of the Montana Business Corporation Act, Sections35-1-826 through35-1-839.Revised Code of Washington. Exercise of these rights will result in the purchase of your shares of IMBCFGW common stock at “fair value,” as determined in accordance with MontanaWashington law. If you elect to exercise this right, we encourage you to consult with your financial and legal advisors. Please read the section entitled “The Merger – Dissenters’ Rights of Appraisal”Rights” for additional information.

Who can help answer my questions?

If you have questions about the merger, the special shareholdersshareholders’ meeting, or your proxy, or if you need additional copies of this document or a proxy card, you should contact:

Inter-Mountain Bancorp.,Community Financial Group, Inc.

208 East Main222 North Wall Street

Bozeman, Montana 59715Suite 300

ATTN: Valarie Abraham,Spokane, Washington 99201

Attention: Tina Campbell, Board Secretary

Tel. No. (406)Telephone: (509) 585-3800242-5626

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RISK FACTORS

In addition to the other information contained in or incorporated by reference into this document, including the matters addressed under the caption “Cautionary Note Regarding Forward-Looking Statements,” you should consider the matters described below carefully in determining whether or not to approve the merger agreement and the transactions contemplated by the merger agreement.

Risks Associated with the Proposed Merger

Because you are receiving a fixed number of shares (subject to adjustment) and the market price of the Glacier common stock may fluctuate, you cannot be sure of the value of the shares of Glacier common stock that you will receive.

At the time of the IMBCFGW special shareholder meeting, and prior to the closing of the merger, you will not be able to determine the value of the Glacier common stock that you will receive upon completion of the merger. Any change in the market price of Glacier common stock prior to completion of the merger will affect the value of the consideration that IMBCFGW shareholders will receive in the merger. Common stock price changes may result from a variety of factors, including but not limited to general market and economic conditions, changes in Glacier’s business, operations and prospects, and regulatory considerations. Many of these factors are beyond the control of Glacier or IMB. On November 30, 2017, the closing price of Glacier common stock was $40.05.CFGW. You should obtain current market prices for Glacier common stock.

The merger agreement provides that the numberresults of sharesoperations of Glacier common stock to be issued for each share of IMB common stock inafter the merger may be decreased or increased, asaffected by factors different from those currently affecting the caseresults of operations of CFGW.

The businesses of Glacier and CFGW differ in certain respects and, accordingly, the results of operations of the combined company and the market price of the combined company’s common shares may be ifaffected by factors different from those currently affecting the average closing priceindependent results of operations of CFGW and Glacier. For a discussion of the business of Glacier common stock, determined pursuant to the merger agreement, is greater than or less than specified prices. If Glacier’s average closing price determined in accordance with the merger agreement is greater than $42.11 and Glacier elects to terminate the merger agreement, the IMB Board would make the decision, without resoliciting the vote of IMB shareholders, whether or not to accept a decrease on aper-share basis in the number of shares of Glacier common stockcertain factors to be issuedconsidered in connection with Glacier’s business, see “Information Concerning Glacier” and the mergerdocuments incorporated by reference in this document and referred to avoid such termination. See “The Merger – Terminationunder “Where You Can Find More Information.” For a discussion of the Merger Agreement.business of CFGW and certain factors to be considered in connection with CFGW’s business, see “Information Concerning Community Financial Group, Inc.” and the documents referred to under “Where You Can Find More Information.”

The merger agreement limits IMB’sCFGW’s ability to pursue other transactions and provides for the payment of abreak-up fee if IMBCFGW does so.

While the merger agreement is in effect, subject to very narrow exceptions, IMBCFGW and its directors, officers, employees, agents and representatives are prohibited from initiating or encouraging inquiries with respect to alternative acquisition proposals. The prohibition limits IMB’sCFGW’s ability to seek offers from other potential acquirersacquirors that may be superior from a financial point of view to the proposed transaction. If IMBCFGW receives an unsolicited proposal from a third party that is superior from a financial point of view to that made by Glacier and the merger agreement is terminated, IMBCFGW will be required to pay a $6,500,000$3,100,000 break-up fee. This fee makes it less likely that a third party will make an alternative acquisition proposal. See “The Merger –Break-Up Fee.”

Combining ourthe two companies may be more challenging, costly or time-consuming than we expect.expected.

Glacier and IMBCFGW have operated and, until the completion of the merger, will continue to operate, independently. Although Glacier has successfully completed numerous mergers in the recent past, this is the largest merger to date and it is possible that the integration of FSBthe Bank into Glacier Bank could result in the loss of key employees, the disruption of the ongoing business of IMBthe Bank or inconsistencies in standards,

controls, procedures and policies that adversely affect ourthe Bank’s ability to maintain relationships with customers and employees or to achieve the anticipated

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benefits of the merger. As with any merger of banking institutions, there also may be disruptions that cause usthe Bank to lose customers or cause customers to take their deposits out of FSB.the Bank.

UnanticipatedWe may face unanticipated costs relating to the merger could reduce Glacier’s future earnings per share.merger.

Glacier believes that it has reasonably and conservatively estimated the likely costs of integrating the operations of FSBthe Bank into Glacier Bank, and the incremental costs of operating as a combined financial institution. However, it is possible that unexpected transaction costs or future operating expenses, as well as other types of unanticipated adverse developments,costs, including as a result of the substantial commitment of time and resources by Glacier’s management to the merger, could have a material adversenegative effect on the results of operations and financial condition of Glacier after the merger.

The merger agreement may be terminated in accordance with its terms and the merger may not be completed, which could have a negative impact on CFGW.

The merger agreement is subject to a number of conditions that must be fulfilled in order to close. Those conditions include: approval by the shareholders of CFGW, receipt of all required regulatory approvals, the continued accuracy of certain representations and warranties by both parties (subject to the materiality standards set forth in the merger agreement), and the performance by both parties of certain covenants and agreements. In addition, certain circumstances exist in which CFGW may terminate the merger, including by accepting a superior proposal. There can be no assurance that the conditions to closing the merger will be fulfilled or that the merger will be completed.

If the merger agreement is completed and unexpected costs are incurred,terminated, there may be various consequences to CFGW, including:

The opinion of CFGW’s financial advisor delivered to the CFGW Board before the execution of the merger agreement does not reflect any changes in circumstances subsequent to the date of the opinion.

The opinion of Piper Sandler regarding the fairness, from a dilutive effect on Glacier’s earningsfinancial point of view, of the per share meaning earnings per share could be less than they would be ifstock consideration in the merger had not been completed.

Glacier has provisionswas delivered to the CFGW Board on August 8, 2023, and speaks only as of such date. Changes in its articles of incorporation that could impede a takeover of Glacier.

Glacier’s articles contain provisions providing for, among other things, preferred stockoperations and super majority shareholder approval of certain business combinations. Although these provisions were not adopted for the express purpose of preventing or impeding the takeover of Glacier without the approval of Glacier’s board of directors, they may have that effect. Such provisions may prevent you from taking part in a transaction in which you could realize a premium over the current market price of Glacier common stock. See “Comparison of Certain Rights of Holdersprospects of Glacier and IMB Common Stock” for a descriptionCFGW, general market and economic conditions, and other factors both within and outside of Glacier’s potential takeover provisions.and CFGW’s control may significantly alter the relative value of the companies by the time the merger is completed. Piper Sandler’s opinion does not speak as of the time the merger will be completed or as of any date other than the date of such opinion.

After the merger is completed, IMBCFGW shareholders will become Glacier shareholders and will have different rights that may be less advantageous than their current rights.

Upon completion of the merger, IMBCFGW shareholders will become Glacier shareholders. Differences in IMB’sCFGW’s articles and IMB’sCFGW’s bylaws and Glacier’s articles and Glacier’s bylaws will result in changes to the rights of IMBCFGW shareholders who become Glacier shareholders. See “Comparison of Certain Rights of Holders of Glacier and IMBCFGW Common Stock.Shares.”

CFGW’s shareholders will have a significantly reduced ownership and voting interest after the merger and will exercise less influence over management.

CFGW’s shareholders currently have the right to vote in the election of the CFGW Board and on other significant matters affecting CFGW, such as the proposed merger with Glacier. When the merger occurs, each

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CFGW shareholder will become a shareholder of Glacier with a percentage ownership of the combined organization that is much smaller than the shareholder’s percentage ownership of CFGW. Based on the anticipated number of Glacier common shares to be issued in the merger, it is anticipated that the CFGW shareholders will own approximately 2.14% of all of the outstanding shares of Glacier’s common stock following the merger. Because of this, CFGW’s shareholders will have significantly less influence on the management and policies of Glacier than they now have on the management and policies of CFGW.

The merger may fail to qualify as a reorganization for federal tax purposes, resulting in the recognition by CFGW’s shareholders of taxable gain or loss in respect of their CFGW shares.

Glacier and CFGW intend the merger to qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code. Glacier and CFGW, as a condition to closing, will each obtain an opinion from their respective legal counsel that the merger will qualify as a reorganization for federal tax purposes. These opinions do not bind the Internal Revenue Service or the courts or prevent either from taking a contrary position. Neither Glacier nor CFGW has requested and neither intends to request any ruling from the Internal Revenue Service as to the U.S. federal income tax consequences of the merger. Furthermore, if the merger fails to qualify as a reorganization, Glacier, as successor to CFGW, may incur a significant tax liability since the merger would be treated as a taxable sale of CFGW’s assets for U.S. federal income tax purposes.

Glacier and CFGW will be subject to business uncertainties and contractual restrictions while the merger is pending.

Uncertainty about the effect of the merger on employees, customers and vendors may have an adverse influence on the business, financial condition and results of operations of Glacier and CFGW. These uncertainties may impair Glacier’s and CFGW’s ability to attract, retain and motivate key personnel, maintain current deposit levels, and continue to attract depositors and attract new borrowers pending the consummation of the merger, as such personnel, depositors and borrowers may experience uncertainty about their future relationships following the consummation of the merger. Additionally, these uncertainties could cause customers (including depositors and borrowers), suppliers, vendors and others who deal with Glacier or CFGW to seek to change existing business relationships with Glacier, CFGW or the combined company or fail to extend an existing relationship with Glacier, CFGW or the combined company.

In addition, the merger agreement restricts CFGW from taking certain actions without Glacier’s consent while the merger is pending. These restrictions could have a material adverse effect on CFGW’s business, financial condition and results of operations. See “The Merger — Covenants” for a description of the restrictive covenants applicable to CFGW.

Failure to complete the merger could negatively impact the stock prices and future businesses and financial results of Glacier and CFGW.

If the merger is not completed, the ongoing businesses of Glacier and CFGW may be adversely affected, and Glacier and CFGW will be subject to several risks, including the following:

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In addition, if the merger is not completed, Glacier and/or CFGW may experience negative reactions from the financial markets and from their respective customers and employees. Glacier and/or CFGW also could be subject to litigation related to any failure to complete the merger or to cause them to perform their respective obligations under the merger agreement. If the merger is not completed, Glacier and CFGW cannot assure their respective shareholders that the risks described above will not materialize and negatively affect the business, financial results or stock prices of Glacier and/or CFGW.

The merger is subject to the receipt of approvals and/or waivers or non-objections from governmental authorities that may delay the date of completion of the merger or impose conditions that could have an adverse effect on Glacier.

Before the merger may be completed, various approvals, waivers or non-objections must be obtained from state and federal governmental authorities, including the Federal Deposit Insurance Corporation, the Board of Governors of the Federal Reserve System, the Commissioner of the Montana Division of Banking and Financial Institutions, and the Washington State Department of Financial Institutions. Obtaining the approval or satisfying the requirements of these governmental authorities may delay the date of completion of the merger, including due to any or all of the following: an adverse development in either party’s regulatory standing or any other factors considered by regulators in granting such approval; governmental, political or community group inquiries, investigations or opposition; or changes in legislation or the political environment. In addition, these governmental authorities may impose conditions on the completion of the merger, or require changes to the terms of the merger. While Glacier and CFGW do not currently expect that any such conditions or changes would result in a material adverse effect on Glacier, there can be no assurance that they will not, and such conditions or changes could have the effect of delaying completion of the merger, or imposing additional costs on or limiting the revenues of Glacier following the merger, any of which might have a material adverse effect on Glacier following the merger. The parties are not obligated to complete the merger should any required regulatory approval, waiver or non-objection contain a condition or requirement not normally imposed in such transactions that would deprive Glacier of the economic or business benefits of the merger in a manner that is material relative to the aggregate economic or business benefits of the merger to Glacier.

Certain CFGW directors and executive officers may have interests in the merger that differ from, or are in addition to, the interests of the shareholders.

In addition to their interests as shareholders generally, certain members of the CFGW Board and executive management may have other interests in the merger. The CFGW Board was aware of these interests and considered them, among other things, when deciding to approve the merger agreement. For a more detailed discussion of these interests, see “Interests of CFGW Directors and Executive Officers in the Merger.”

Recent events impacting the financial services industry could exacerbate the risks associated with the merger.

The adverse events during the first part of 2023 involving Silicon Valley Bank, Signature Bank, and First Republic Bank caused significant volatility in the trading prices of stock of publicly traded bank holding companies and have decreased confidence in banks among depositors and investors. These adverse events also led bank regulators to signal further review of regulatory requirements and the potential for changes to laws or regulations governing banks and bank holding companies. These ramifications could extend to the merger and increase the risk of losing depositors and heightened regulatory scrutiny of the merger.

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Risks Associated with Glacier’s Business

Glacier is, and will continue to be, subject to the risks described in Glacier’s Annual Report on Form10-K for the fiscal year ended December 31, 2016,2022, as updated by aits Quarterly Report on Form10-Q for the quarter ended SeptemberJune 30, 2017,2023, and subsequent Current Reports on Form8-K, and Quarterly Reports on Form10-Q, all of which are filed with the SEC and incorporated by reference into this proxy statement/prospectus. See “Documents Incorporated by Reference”“References to Additional Information” and “Where You Can Find More Information About Glacier”Information” included elsewhere in this proxy statement/prospectus.

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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,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 our respectiveGlacier’s and CFGW’s plans, objectives, expectations, intentions, projected financial information, future opportunities and intentions andany other statements regarding Glacier’s and CFGW’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(iii) (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 CFGW’s management and are inherently subject to significant business, economic and competitive uncertainties and contingencies, many of which are beyond Glacier’s and IMB’sCFGW’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 risk factors described above,previously disclosed in Glacier’s reports filed with the SEC relating to risks to Glacier’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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Additional

The foregoing list of factors is not intended to be exhaustive. These forward-looking statements reflect Glacier’s and CFGW’s current views with respect to future events and are based on numerous assumptions and assessments made by Glacier and CFGW 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 CFGW’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 discussedreasonable, 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 Glacier’s reports filed with the SEC.

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 IMBCFGW or any person acting on behalf of Glacier or IMBCFGW are expressly qualified in their entirety by the cautionary statements above. Neither Glacier nor IMBCFGW 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.

SELECTED HISTORICAL FINANCIAL INFORMATION OF GLACIER

The following table presents selected consolidated financial information of Glacier for the fiscal years ended December 31, 2016, 2015, 2014, 2013, and 2012. The consolidated financial data of and for the nine months ended September 30, 2017 and 2016 are derived from unaudited condensed consolidated financial statements, has been prepared on the same basis as the historical information derived from audited financial statements and, in the opinion of Glacier’s management, reflects all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of this data at or for those dates. The results of operation for the nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the entire year ending December 31, 2017. The consolidated financial data below should be read in conjunction with the consolidated financial statements and notes thereto, incorporated by reference in this proxy statement/prospectus. See “Where You Can Find More Information About Glacier.”

COMPARATIVE STOCK PRICE AND DIVIDEND INFORMATION

Glacier Common Stock

Glacier common stock is quoted on The NASDAQ Global Select MarketNew York Stock Exchange under the symbol “GBCI.” The following table sets forth for the periods indicated:

At October 31, 2017,

As of September 25, 2023, the 78,006,956110,879,365 outstanding shares of Glacier common stock were held by approximately 1,7031,763 holders of record.

IMBCFGW Common Stock

IMBPublic trading in CFGW’s common stock has not been extensive and such trades cannot be characterized as constituting an active trading market. CFGW common stock is not publicly tradedlisted on any national securities exchange, although it is quoted on the OTC Markets under the ticker symbol “CFGW.” Quotations are based on information received from the OTC Markets based on all transactions reported on the OTC Markets. Such information reflects inter-dealer prices, without retail markups, markdowns or commissions and has been traded only very infrequently. The trades that have occurred have been in accordance with the terms of the Amended and Restated Shareholder Agreement (as subsequently amended, the “Shareholder Agreement”). IMB shares covered by the Shareholder Agreement are generally subject to a right of first refusal of IMB and IMB shareholders other than the proposed transferee. The Shareholder Agreement also prohibits any transfer of IMB shares that would, or with the passage of time would, cause a termination of IMB’s election to be subject to subchapter S of the Internal Revenue Code. Upon consummation of the merger, the Shareholder Agreement will be terminated.

IMB receives an annual independent estimated valuation of its outstanding common stock. The following table states the valuation per share of IMBmay not reflect actual transactions. CFGW’s common stock as of December 31 ofis quoted on the year stated:

forth for its securities. Fromthe periods indicated, the high and low quotations for CFGW common stock along with the aggregate number of shares publicly reported as traded for each applicable quarter.

IMBCFGW SPECIAL SHAREHOLDERS’ MEETING

Date, Time, Place

The IMBCFGW special meeting of shareholders will be held on January 16, 2018November 14, 2023, at 1:3:00 p.m. MountainPacific Time in the Communityat 222 North Wall Street, Lower Level Conference Room, of the First Security Bank branch located at 670 19^th Avenue, Bozeman, Montana 59715.Spokane, Washington 99201.

As described below under “Votes Required and Quorum,” approval of the merger agreement requires the affirmative vote of at leasttwo-thirds (66 2/3%) a majority of the outstanding shares of IMB’s outstandingCFGW’s common stock.stock entitled to vote on the matter. 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 againstopposing the proposal, assuming a quorum is present. If less than a quorum is represented at the special meeting, a majority of the shares so represented may adjourn the special meeting without further notice.proposal.

Purpose

At the special meeting, IMBCFGW shareholders will:

Record Date; Shares Outstanding and Entitled to Vote

The IMBCFGW Board has fixed 5:00 p.m. Mountain Timethe close of business on December 1, 2017September 27, 2023, as the record date for determining the holders of shares of IMBCFGW common stockshares entitled to notice of and to vote at the special meeting. At the close of business on the record date, there were approximately 126444 holders of record and 203,7632,136,808 CFGW common shares of IMB common stock issued and outstanding. Holders of record of IMBCFGW common stockshares on the record date are entitled to one vote per share and are also entitled to exercise dissenters’ rights if certain procedures are followed. See “The Merger – Dissenters’ Rights of Appraisal” andAppendix B.share.

IMB’sCFGW’s directors and certain IMB shareholdersof CFGW’s executive officers have agreed to vote all shares of IMBCFGW common stockshares 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, hereof,to CFGW’s knowledge, a total of 120,530612,869 CFGW common shares, of IMB common stock, representing approximately 59.15%28.7% of all outstanding CFGW common shares, of IMB common stock, are covered by thesubject to voting agreements. See “The Merger – Interests of Certain Persons in the Merger – Voting Agreements.”Agreements”.

Votes Required and Quorum

The affirmative vote of the holders of at leasttwo-thirds (66 2/3%) a majority of the outstanding shares of IMB’s outstandingCFGW’s common stock entitled to vote is required to approve the merger agreement. At least a majority of the total outstanding CFGW common shares of IMB common stockentitled to vote must be present, either in personat the meeting or by proxy, in order to constitute a quorum for the special meeting. For purposes of determining a quorum, abstentions areand broker non-votes will be counted in determining the shares present at a meeting.

For voting purposes, however, shares must be affirmatively votedFOR 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.

If less than a quorum is represented at the special meeting, a majority of the shares so represented may adjourn the special meeting without further notice. The proposal to adjourn the special meeting, if necessary or appropriate, including adjournmentsan adjournment to solicit additional proxies in favor of the merger agreement, will be approved if a quorum is present at the special meeting and the votes cast in favor of the proposal exceed the votes cast againstopposing the proposal, assuming a quorum is present.proposal.

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Voting, Solicitation, and Revocation of Proxies

If you are a holder of record of CFGW 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 proxyFOR the approval of the merger agreement, andFOR 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:

IMBCFGW is soliciting the proxy for the special meeting on behalf of the IMBCFGW Board. IMBCFGW will bear the cost of solicitation of proxies from its shareholders. In addition to using the mail, IMBCFGW may solicit proxies in person or by personal interview, telephone, and facsimile.email or facsimile, in each case without compensation. 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. IMB does not expect to pay any compensation for the solicitation of proxies. However, IMBCFGW 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 in Person at the Special Meeting

Shares helddirectly in your name as the shareholder of record may be voted in person at the special meeting. If you choose to vote your shares of IMBCFGW common stockshares in person, please bring the enclosed proxy card or proof of identification. Even if you plan to attend the special meeting, we recommend that you vote your shares of IMBCFGW common stock 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 at 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 CFGW Proposals

Proposal 1: Merger Proposal

CFGW 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.” CFGW shareholders

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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 CFGW 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 CFGW and the CFGW 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 CFGW’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 in person at the 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 CFGW common shares is a condition to the completion of the merger.

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

Proposal 2: Adjournment Proposal

CFGW is asking its shareholders to approve the adjournment of the CFGW 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 CFGW special meeting, an insufficient number of CFGW common shares are present in person or represented by proxy and voting in favor of the merger proposal, CFGW will move to adjourn the CFGW special meeting to enable the CFGW Board to solicit additional proxies for approval of the merger proposal. If the CFGW shareholders approve the adjournment proposal, CFGW may adjourn the CFGW special meeting and use the additional time to solicit additional proxies, including the solicitation of proxies from CFGW shareholders who have previously voted. If the date of the adjournment is not announced at the CFGW 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. 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 in person at the CFGW 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 CFGW Board recommends that CFGW shareholders vote “FOR” the adjournment proposal.

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BACKGROUND OF AND REASONS FOR THE MERGER

Background of the Merger

From time to time over the past several years, the IMB Board, with the assistance from time to timeAs part of ProBank Austin (“ProBank”), discussed and consideredits ongoing strategic alternativesplanning to enhance shareholder value, the CFGW Board and achieveexecutive management regularly review and assess CFGW’s strengths, weaknesses, strategic opportunities and challenges, in an ever changing and more complex operating environment. The CFGW Board considered the prospects for continued strong growth and profitability, particularly in light of the difficulties operating as an independent community bank under current economic, regulatory and competitive conditions. Like many other banks, CFGW experienced increasing costs related to information technology, regulatory compliance, product development and personnel, to remain competitive with bank and non-bank competitors, including financial technology companies. In addition, after over 40 years of operations, CFGW was facing a heightened level of succession risk that was difficult to address, as an increasing number of CFGW’s directors and senior management approached or passed normal retirement age. On top of this, CFGW’s aging shareholder base has been increasingly in search of more stock trading liquidity. The CFGW Board has also monitored the changing community banking landscape in the region, including the decline in potential buyers who could execute on a transaction that would be appealing to CFGW.

Given the changing community banking landscape in the region, regulatory compliance burdens, rising information technology costs, risks associated with director and officer succession planning, and the growing desire for increased CFGW shareholder liquidity, the CFGW Board grew increasingly interested in strategic alternatives that could address these challenges. In reviewing its alternatives, the CFGW Board considered the best ways to maximize CFGW shareholder value, maximize the opportunities for CFGW’s employees and secure the Bank’s long-term future shareholderand ability to serve its customers and communities. The CFGW Board carefully considered many strategic alternatives, including: (i) continued organic growth, which would be limited by CFGW’s finite capital resources; (ii) growth through CFGW’s acquisition of smaller institutions, which would be challenging given the lack of viable attractive targets, CFGW’s limited capital resources and the illiquidity of CFGW’s stock; or (iii) merging with a larger bank with more resources to support continued strong financial performance, and provide CFGW shareholders with greater liquidity. In considering these alternatives, the CFGW Board consistently viewed a merger with a larger bank as the alternative that best achieved its strategic objectives. As a result, the CFGW Board and management decided to continue to emphasize organic growth while undertaking strategic initiatives that would maximize the attractiveness of CFGW to potential acquirors. As part of these efforts, early in 2021 the CFGW Board began meeting periodically with Piper Sandler to review developments in the banking industry, including mergers and acquisitions trends, bank performance trends and bank stock valuations. Piper Sandler is a nationally recognized investment banking firm with substantial experience advising financial institutions generally, including with respect to mergers and acquisitions. At the direction of the CFGW Board, Susan Horton, CFGW’s Chairman, CEO and President, began developing relationships with a group of potential merger partners that best aligned with the CFGW Board’s strategic priorities.

Throughout 2021 and 2022, Ms. Horton held in person and telephonic meetings with the CEOs of several potential merger partners, including Randy Chesler, CEO of Glacier, with the intent of learning more about the potential strategic fit between CFGW and the respective merger partners and developing relationships that could help facilitate a potential merger at some point in the future. During thatthis time, inmid-2016Ms. Horton reported to the CFGW Board on the content of the meetings with potential partners and again in early 2017, a bank holding company, which we will refer to as Party B, through its independent financial adviser,these reports were often accompanied by analytical updates provided by Piper Sandler. In meetings with Ms. Horton, Mr. Chesler expressed Glacier’s interest in pursuing a merger with CFGW and indicated that the most desirable timing for Glacier would be to begin substantive discussions regarding the possibility of a merger in the winter of 2022-2023.

Based on Ms. Horton’s reports and the financial analyses provided by Piper Sandler, Glacier’s unique community banking model and Glacier’s superior financial performance over a long period, among other considerations, the CFGW Board concurred at a meeting on November 10, 2022, that Glacier was the partner

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most capable of structuring a merger that met the strategic objectives of the CFGW Board, namely: to maximize value and liquidity for CFGW shareholders, to maximize the opportunities for CFGW’s employees, and to secure the Bank’s long-term future and ability to serve its customers and communities.

In February 2023, Ms. Horton was contacted by Glacier and invited to a meeting at Glacier’s corporate headquarters. At the meeting on March 7, 2023, Ms. Horton met with Mr. Chesler and other Glacier executives, shared information about CFGW, and learned more about Glacier and its history and approach to mergers and acquisitions and how CFGW and the Bank might benefit from a merger with Glacier. At that meeting Mr. Chesler expressed the interest of Glacier’s board of directors in further exploring an acquisition of CFGW, with the first step being working towards a non-binding letter of intent. On March 10, 2023, Ms. Horton and Piper Sandler met with the CFGW Board to discuss further the potential for a transaction with Glacier as compared to CFGW’s other strategic alternatives, and the CFGW Board agreed to convey to Mr. Chesler their desire to work towards a non-binding letter of intent. Ms. Horton communicated this to Mr. Chesler later that day, and Mr. Chesler indicated that the next step would be for CFGW to provide Glacier with some initial financial information and other information regarding CFGW after CFGW’s first quarter 2023 financial information was available. On March 31, 2023, Mr. Chesler requested that Ms. Horton provide first quarter 2023 and other financial information regarding CFGW. On April 11, 2023, Ms. Horton provided Glacier with the requested information.

In late April and early May 2023, representatives from Glacier’s financial advisor, Keefe, Bruyette & Woods, Inc. (“KBW”), met with Glacier management to discuss the letter of intent and its proposed terms and the potential financial impact of the transaction on Glacier.

On May 8, 2023, Glacier provided CFGW with a non-binding letter of intent which outlined the high-level terms of a proposed merger, including 100% stock consideration and a fixed exchange ratio of 1.0931 Glacier shares in exchange for each share of CFGW. In the days following receipt of the non-binding letter of intent, the financial and legal advisors of CFGW analyzed the financial merits and other significant terms of Glacier’s proposal.

On May 16, 2023, the CFGW Board held a special meeting, along with Piper Sandler and CFGW’s legal counsel, Otteson Shapiro LLP (“Otteson Shapiro”) to review, consider, and discuss Glacier’s proposal. At the meeting, Otteson Shapiro reviewed with the CFGW Board their fiduciary duties in connection with the consideration of the non-binding letter of intent. At the meeting, the CFGW Board considered Glacier’s proposal, CFGW’s stand-alone prospects and the landscape of other potential merger partners for CFGW. The CFGW Board discussed the benefits and drawbacks of Glacier’s proposal and considered how the proposal might be negotiated to better meet the objectives of the CFGW Board. The CFGW Board also discussed the then-current turmoil in the banking industry, including the recent failure of multiple banks and the overall significant decline in bank stock values, and whether it would be possible to meet the objectives of the CFGW Board during such an environment. As part of this consideration, the CFGW Board considered the fact that the Glacier proposal consisted of 100% stock consideration with a fixed exchange ratio, meaning that CFGW shareholders would stand to benefit from a potential strategic transaction with or acquisitionrecovery in the banking industry through the ownership of IMB. In respectGlacier stock, and in addition, that Glacier had a track record of superior financial and stock price performance over the long term. At the conclusion of the meeting, the CFGW Board expressed its sincere interest expressed by Party B,in Glacier’s proposal, and againauthorized Ms. Horton, with the assistance of ProBank,Piper Sandler and Otteson Shapiro, to clarify and negotiate certain terms of the IMBnon-binding letter of intent, including but not limited to: requesting an increase in the merger consideration to be received by CFGW shareholders and the removal of a stock-price based collar mechanism that could potentially limit the upside to CFGW shareholders during the pendency of the merger if stock prices in the banking industry increased significantly.

On May 19, 2023, CFGW conveyed to Glacier a package of additional financial information regarding CFGW that CFGW believed would assist Glacier in refining and improving the terms of its merger proposal. In addition to the financial information, CFGW shared with Glacier a list of requested clarifications and

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amendments to the non-binding letter of intent, including but not limited to an increase in the merger consideration and the removal of the stock-price based collar mechanism. Over the course of the next five days, representatives of CFGW and Glacier discussed and negotiated the terms of the proposal and, on May 24, 2023, Glacier submitted to CFGW an updated non-binding letter of intent. Representatives from CFGW and Glacier continued to discuss and negotiate certain components of the updated non-binding letter of intent.

On June 1, 2023, the CFGW Board held a special meeting, along with Piper Sandler and Otteson Shapiro to review Glacier’s updated proposal. The CFGW Board reviewed the clarifications and amendments to the initial proposal. The CFGW Board raised some additional questions and amendments to the non-binding letter of intent and authorized Ms. Horton and CFGW’s legal and financial advisors to engage further with Glacier to clarify and improve the proposed terms for the benefit of CFGW’s shareholders.

In the following days, Ms. Horton and Mr. Chesler, along with the respective legal and financial representatives of CFGW and Glacier, engaged in formala series of discussions regarding Glacier’s proposal and, on June 5, 2023, Glacier submitted an updated non-binding letter of intent to CFGW.

On June 6, 2023, the CFGW Board held a special meeting, along with Piper Sandler and Otteson Shapiro, to review Glacier’s updated proposal. The CFGW Board reviewed the clarifications and amendments to the initial proposal, including that there was no increase to the stock consideration to be received by CFGW shareholders, but that the stock-price based collar was removed from the proposed terms as requested, thus removing a limitation on CFGW shareholders’ ability to benefit from significant increases in the price of Glacier common stock. Following a thorough discussion, the CFGW Board authorized Ms. Horton to execute the non-binding letter of intent, which contemplated the sale of CFGW to Glacier and that CFGW shareholders would receive 1.0931 shares of Glacier in exchange for each CFGW share (subject to adjustment in certain circumstances). In making the decision to execute the non-binding letter of intent, the CFGW Board determined that the proposed merger with Glacier would be beneficial for CFGW and its shareholders based on several factors, including, but not limited to: the long-term financial prospects of the proposed merger as compared to the prospects of CFGW on a stand-alone basis or with other potential acquirors; the strategic planning meetingsfit of CFGW and Glacier; the all-stock nature of the merger consideration; and the fact that, post-merger, the Bank would continue to identifyoperate and evaluateserve its customers and communities as a division of Glacier Bank and would enjoy the key strategic issues facing the organization. The first such meeting was held October 18, 2016 and a second was held January 17, 2017.

At these meetings specifically, the IMB Board identified several important planning issues, including existing and anticipated liquidity requests from IMB shareholders, the amount of parent holding company debt and debt service obligations, management and board of director succession at both IMB and FSB, regulatory capital requirements and alternatives for capital formation, and FSB strategic plans for expansion and growth. Notably, the October 2016 meeting included discussions of various capital planning strategies, income tax elections and status, costs and benefits of registration underbeing combined with Glacier’s existing North Cascades Bank division, including the United States federal securities lawsBank being in the top 5 in deposit market share in eastern Washington. In considering these and other factors, the CFGW Board determined that the proposed merger with Glacier represented a transaction that was in the best interest of IMB securities withCFGW and its shareholders in the Securitieslong-term and Exchange Commission, strategicexecuted the non-binding letter of intent on June 7, 2023.

On June 15, 2023, Glacier and CFGW executed a mutual nondisclosure agreement to facilitate the due diligence process.

During June, July and August of 2023, the parties conducted significant due diligence and negotiated the definitive merger alternatives,agreement and potential transactions with publicly traded bank holding companies.

In January 2017, the IMB Board held its second strategic planning meeting to continue the review and discussionancillary agreements. Glacier provided an initial draft of the various strategic issuesmerger agreement to CFGW on July 11, 2023. During the next few weeks, Otteson Shapiro and alternatives discussed at the October 2016 planning meeting, and to consider other options and alternatives to the extent available.

Then, in late January 2017, IMB’s executive management and ProBank met with executive management of a different bank holding company, which we will refer to as Party C, to discuss a possible strategic merger or other transactionCFGW discussed and negotiated with IMB. Based on these discussions, the strategic alternatives presented by and contemplated with Party C were determined not practicable and discussions terminated.

Following the termination of the discussions with Party C, the IMB Board developed over the next several weeks a strategic plan based in part on decisions made at the strategic planning meetings and in light of its meeting with Party C. The strategic plan outlined the IMB Board’s current decision to maintain IMB’s election to be taxed subject to Subchapter S of the Internal Revenue Code, evaluate changes to the IMB Amended and Restated Shareholder Agreement, continue IMB’s dividend policy of distributing income to its shareholders at the highest marginal combined individual personal income tax rates, manage FSB’s capital level and pay excess capital to its parent holding company, develop management and board of director succession plans for IMB and FSB, and make a decision by June 30, 2017 about whether to raise capital to fund possible debt reduction and share repurchases and to be used for other general corporate purposes. Finally, the IMB Board noted its desire to remain an independent bank holding company, but that it would in furtherance of the exercise of its fiduciary duties to shareholders remain open to considering all possible strategic alternatives.

In early May 2017, the Chief Executive Officer of Party B again contacted IMB through ProBank to express Party B’s continuing interest in effecting a strategic transaction with IMB. At a meeting of IMB’s Board on May 16, 2017, at which IMB’s outsideMiller Nash LLP (“Miller Nash”), Glacier’s legal counsel, and financial adviser participated,management of Glacier the IMB Board discussed an appropriate response to the Party B expression of interest. Following deliberation, at a meeting held on May 18, 2017, the IMB Board instructed ProBank to request subject tovarious legal and business terms of confidentiality a term sheet from Party B that would outline in reasonable detail the salient terms of its proposal for further considerationmerger agreement and deliberationthe proposed merger. The parties exchanged multiple drafts of the IMB Board.

Thereafter, on June 7, 2017, Party B communicated a verbal indicationmerger agreement and ancillary agreements and had numerous calls to discuss and negotiate various issues. Primary subjects of interest through Party B’s independent financial advisorthese negotiations included tax, accounting and contract issues relating to ProBank. Party B proposed in general terms to acquire IMB for approximately $153 million payable in Party B’s publicly traded common stock, subject to confirmatory due diligence, regulatory approvalslabor and other customary conditions. On June 21, 2017,employee benefit matters, including employee compensation after the IMB Board met with ProBank and outside legal counsel to IMB to evaluate and discuss Party B’s indication of interest. The IMB Board also discussed other potential merger partners, the advantages and disadvantages of a broad marketing of IMB for sale, and IMB’s strategic plan. Glacier was then identified as a resultclosing of the discussions as an attractive potential merger partner in viewmerger; the means by which CFGW’s capital would be calculated at closing; the treatment of Glacier’s successful track record with other acquisitions, its emphasis on locally managed community banking, its strong historical financial performance andcertain merger-related expenses; the strong historical performance of Glacier common stock and related dividend payouts. Following discussion and considerationtiming of the alternatives,merger; the IMB Board authorized executive management and ProBank to contact Glacier’s executive management to inquire whether Glacier had a potential interest in acquiring IMB.

On June 22, 2017, Bruce Gerlach, IMB’s President and Chief Executive Officer, at the directionoperations of the IMB Board, contacted subjectBank between signing and closing; representations, warranties and covenants of CFGW and Glacier; and conditions to termsclosing of confidentiality representatives at both Glacier and D. A. Davidson & Co., financial advisor to Glacier (“Davidson”), to see if Glacier would have interest in discussions about a potential combination with IMB. Later that same day, representatives from ProBank sent Davidson information on IMB and a timeline of when they would like to receive a written indication of interest.

On June 29, 2017, Randy Chesler, Glacier’s Chief Executive Officer, and other representatives from Glacier and IMB met to discuss each organization’s approach to community banking and to discuss a possible transaction.the merger.

On July 7, 2017, Davidson,13, 2023, the CFGW Board met, along with Piper Sandler and Otteson Shapiro, to discuss the status of the ongoing negotiations between the parties. Piper Sandler provided the CFGW Board an update on behalfthe

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implied value of the merger consideration relative to bank stock values in general along with an overview of some of the variables that might impact CFGW’s ability to pay a pre-closing dividend or result in a downward adjustment in the exchange ratio, namely CFGW’s forecast earnings, CFGW’s expected transaction expenses and potential changes in CFGW’s accumulated other comprehensive income related to its investment portfolio. The CFGW Board discussed that, as part of the proposed transaction terms, CFGW would benefit from keeping certain of its transaction-related expenses as low as possible. The payout of certain existing executive employment contracts that would be triggered in the proposed merger was an important component of the expense calculation. To minimize expenses and maximize the possibility of a pre-closing cash dividend for CFGW shareholders, Ms. Horton reported that she was exploring alternatives to defer the majority of the payments otherwise owed to her at closing of the transaction and receive them over a period of three years following closing. As such, the deferred portion of those payments would not be included in the expense calculation, thereby reducing CFGW’s transaction expenses and maximizing the possibility of a pre-closing cash dividend for CFGW shareholders. The CFGW Board commended Ms. Horton for her efforts to maximize value for the CFGW shareholders.

On July 28, 2023, the CFGW Board and the Bank’s board of directors met, along with Piper Sandler and Otteson Shapiro, to discuss the status of the ongoing negotiations between the parties and the terms of the proposed merger. At the meeting, Otteson Shapiro walked the members of the CFGW Board and the Bank’s board of directors through their fiduciary duties in connection with the proposed merger and provided an update on the status of the merger agreement. Piper Sandler provided the CFGW Board and the Bank’s board of directors an update on the value of the merger consideration relative to bank stock values in general, along with an updated overview of the variables impacting CFGW’s ability to pay a pre-closing dividend or experience a downward adjustment in the exchange ratio, namely CFGW’s forecast earnings, CFGW’s expected transaction expenses and potential changes in CFGW’s accumulated other comprehensive income. In this meeting, Ms. Horton reported her intent to defer the majority of payments provided for under her employment agreement for a period of three years following closing, in part by accepting a significantly extended agreement not to compete or solicit customers or employees of the Bank, and that the deferral would reduce CFGW’s transaction expenses and increase the probability of CFGW being able to pay a pre-closing cash dividend to CFGW shareholders.

On August 8, 2023, a special meeting of the Glacier deliveredboard of directors was convened to consider the proposed merger transaction. Members of executive and senior management and representatives of KBW and Miller Nash also attended the meeting at the invitation of the Glacier board of directors. The Glacier board of directors was provided with a nonbinding letterset of intent setting forthmeeting materials in advance of the meeting, including substantially final drafts of the merger agreement, the voting agreements, the director non-competition agreements, Ms. Horton’s employment agreement, and a comprehensive summary of management’s due diligence review of CFGW and the contemplated transaction. 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 and Miller Nash then reviewed the due diligence process and findings in detail. This included a review of credit, compliance, operations, and legal matters based on extensive materials made available to Glacier by CFGW. KBW then reviewed the financial aspects of the proposed transaction, including the key financial terms of the proposed merger. Miller Nash proceeded to review in detail with the Glacier board of directors the terms of the merger agreement, including the terms of various ancillary documents, and the material terms of Ms. Horton’s employment agreement were presented. After considering the proposed terms of the merger includingagreement and related transaction documents, and taking into consideration the principal financial terms.

On July 14, 2017, the IMB Board met, with the assistance of ProBank and outside legal counsel, to evaluate and discuss Glacier’s nonbinding proposal as well as the status of the discussions with and nonbinding proposal of Party B. As a result of the discussions, the IMB Board determined to invite the chief executive officers of both Glacier and Party B to meet with the IMB Board.

On July 18, 2017, representatives from Glacier and Davidson were invited to present their proposal to the IMB Board in Bozeman, Montana. Followingmatters discussed during that meeting ProBank provided to Glacier supplemental information on and answered questions regarding IMB. Representatives of Party B were also invited on July 18, 2017, to present separately their proposal to the IMB Board in Bozeman, Montana. Following theprior meetings the IMB Board instructed ProBank to request final indications of interest from both Glacier and Party B to be delivered.

On July 19, 2017, IMB formally engaged ProBank to provide financial advisory services to IMB in respect of the ongoing process.

On July 24, 2017, representatives from IMB, ProBank, Glacier and Davidson participated in a conference call to discuss IMB’syear-to-date financial and operating results, 2017 budget and 2018 and 2019 projections. Between July 7 and July 28, 2017 the parties and their legal counsel and financial advisors negotiated several aspects of the term sheet, both financial andnon-financial.

On July 26, 2017, Party B delivered an updated nonbinding letter of intent setting forth its updated terms of a merger with Party B.

On July 28, 2017, Davidson, on behalf of Glacier, delivered an updated nonbinding letter of intent setting forth the updated terms of the Glacier merger.

On August 2,board of directors, the IMB Board met with ProBank and legal counsel to discuss the two proposed lettersGlacier board of intent. On the direction of the IMB Board, ProBank presented a counter-proposal to Davidson asking for Glacier to improve its offer in order for IMB to move forward with Glacier on an exclusive basis. After several discussions and review of additional information, Glacier slightly modified and improved its offer and resubmitted its letter of intent on August 2, 2017.

After taking into account both offers, the IMB Board recognized that both were competitive, butdirectors determined that Glacier’s long-term stock and dividend performance and its community banking model werethe merger was in the best interests of itsGlacier and Glacier shareholders, and would better serve its customers, employees and the communities in which IMB operates. Accordingly, the IMB Board decided to move forward with the offer from Glacier.

On August 3, 2017 IMB delivered a signed letter of intent to Glacier, executed a formal and mutualnon-disclosure agreement and Glacier provided its due diligence request list to IMB.

On August 7, 2017, Glacier and its advisors were granted access to a virtual data room that containednon-public financial and operational information.

On August 10, 2017, the IMB Board engaged special transactional legal counsel Holland & Hart LLP to represent IMB in connection with the negotiations of a definitive merger agreement consistent with the terms of the Glacier nonbinding letter of intent.

On September 19, 2017, the IMB Board appointed a negotiation committee with authority to negotiate the terms of a definitive merger agreement with Glacier, subject to the final review and, if appropriate, approval of the full IMB Board. Directors Robert Kamp, Bruce Gerlach and Michael Johnson were appointed to the negotiation committee.

Between August 3 and October 26, 2017, Glacier, IMB and their respective legal counsel and financial advisors conducted appropriate due diligence and drafted and negotiated the merger agreement and related ancillary agreements. Through October 26, 2017, IMB provided Glacier with supplemental information regarding the financial aspects of its business, its markets and its operations. Through October 26, 2017, Glacier provided IMB with information regarding, among other things, its employee benefit policies, its insurance policies and itsnon-competition arrangements with its directors and executive officers. Glacier’s due diligence review included a loan due diligence review conducted by DLS Consulting and supported by Glacier’s Chief Credit Officer and a compliance review conducted by Fortner, Bayens, Levkulich & Garrison, P.C. and supported by Glacier’s Audit and Compliance Director.

On August 22 and 23, 2017, representatives from Glacier and Davidson were accompanied on a due diligence trip by Bruce Gerlach, Steve Wheeler, FSB’s President, and Mike Johnson, FSB’s Northern Market Manager, to review the branches of FSB and its markets. Mr. Chesler, along with other Glacier representatives and a representative from Davidson, met with representatives from IMB and FSB to discuss the transaction and conduct due diligence interviews.

On September 27, 2017, Davidson made a presentation to the Glacier board of directors to discussunanimously approved the potential transaction,execution, delivery and performance of the pro forma financial impact to Glacier,merger agreement and the markets that IMB operates in.transactions contemplated by it, including the merger.

On October 16, 2017, representatives from IMB, ProBank, GlacierAlso on August 8, 2023, the CFGW and Davidson participated inthe Bank Boards of Directors held a reverse due diligence conference callspecial meeting to provide information to IMB regarding Glacierreview and answer questions from IMB and ProBank.

On October 24, 2017, the IMB Board, together with ProBank and legal counsel, met to consider the negotiated proposed definitive merger. At the meeting, representatives of Otteson Shapiro explained the terms of the

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merger agreement. ProBankagreement and related transaction documents, and representatives of Piper Sandler reviewed the financial aspects of the proposed merger and renderedresponded to questions by the IMB Board a verbalCFGW and the Bank Boards of Directors. Additionally, Piper Sandler delivered its oral opinion (commonly referred to as the “fairness opinion”), which was confirmed in writing later on August 8, 2023, to the effect that, as of thatsuch date and subject to the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by ProBank,Piper Sandler as set forth in its opinion, the mergerper share stock consideration in the proposed merger with Glacier was fair, from a financial point of view, to the holders of IMBCFGW common stock. Legal counsel then reviewedAfter further discussion among the specific terms ofdirectors and CFGW’s advisors, including with respect to the merger agreement and the substantial process involvedfactors described in negotiating its terms. Among other matters considered, the IMB Board reviewed the specific terms of the merger agreement, the form and value of the consideration to be received by IMB shareholders, the price and historical performance of Glacier common stock and related dividend payouts, current market conditions including comparable bank merger and acquisition transactions, ancillary agreements“Reasons for the employment of certain FSB employees followingMerger — CFGW” the CFGW Board unanimously determined that the merger and the implications of the merger to IMB’s employees, customers, and communities. After due consideration of these and other matters, and taking into consideration the financial fairness opinion delivered by ProBank, the IMB Board approved entering into the merger agreement.

On October 25, 2017, the board of directors of Glacier, together with its legal counsel and representatives of Davidson, met to consider approval of the definitive merger agreement. Davidson presented updated pro forma financial analyses and Glacier’s legal counsel presented a review of the key terms of the merger agreement were advisable, and related ancillary agreements. Among other matters discussed,in the boardbest interests of, directorsCFGW and Glacier’s advisors discussed the results of due diligence reviews, the terms of the merger agreement and related ancillary agreements, key pricing metrics, the pro forma financial impact of the merger to Glacier’sits shareholders, risks of the merger, and the timingBank, and process for consummation of the merger, including the results of preliminary discussions with bank regulators. After due consideration of these and other matters, the board of directors of Glacierunanimously approved the merger agreement, on October 25, 2017.

On October 26, 2017, ProBank deliveredsubject to shareholder and regulatory approvals, and related actions and recommended the adoption and approval of such agreement and transactions to the IMB Board its written opinion to the effect that, as of that date and subject to the procedures followed, assumptions made, matters considered and qualifications and limitations on the review undertaken by ProBank, the merger consideration in the proposed merger with Glacier was fair, from a financial point of view, to the holders of IMB common stock, and theCFGW shareholders.

The parties executedentered into the merger agreement and related ancillary agreements.on August 8, 2023. After the close of business on October 26, 2017, the partiesAugust 8, 2023, Glacier issued a joint press release announcing the merger.merger transaction.

Reasons For Thefor the Merger – IMBCFGW

At a board meeting held on October 24, 2017,August 8, 2023, the IMBCFGW Board determined that the terms of the merger agreement were in the best interests of IMBCFGW and its shareholders.shareholders and recommended that CFGW’s shareholders vote for approval of the merger agreement. In the course of reaching this determination and related decision to approve the merger agreement, the IMBCFGW Board evaluated the merger and the merger agreement in consultation with the management of IMB and IMB’sCFGW’s financial advisor and legal counsel. In reaching its determination, the IMBCFGW Board considered a number of factors. Such factors also constituted the reasons that the IMBCFGW Board determined to approve the merger agreement and to

recommend that IMBCFGW shareholders vote in favor of the merger agreement. Such reasons included

The following discussion of the information and factors considered by the CFGW Board is not intended to be exhaustive, but, rather, includes the material factors considered by the CFGW 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 CFGW 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 CFGW 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. In reaching its decision to approve the merger agreement, the CFGW Board considered the following:

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Proposal.”

The IMBCFGW Board also considered a number of uncertainties and risks in its deliberations concerning the transactions contemplated by the merger agreement, including the following:

The foregoing discussionOpinion of the reasons that led the IMB BoardCFGW’s Financial Advisor

CFGW retained Piper Sandler to approve the merger agreement and recommend that IMB’s shareholders vote in favor of the merger agreement is not intended to be exhaustive but is believed to include all of the material reasons for the IMB Board’s decision. In reaching its determination to approve and recommend the transaction, the IMB Board based its recommendation on the totality of the information presented to it and did not assign any relative or specific weightsact as financial advisor to the reasons considered in reaching that determination. Individual directors may have given differing weights to different reasons. After deliberating with respect to the merger with Glacier, considering, among other things, the matters discussed above, the IMBCFGW Board unanimously approved the merger agreement and the merger with Glacier as being in the best interests of IMB and its shareholders.

Opinion of IMB’s Financial Advisor

On July 19, 2017, IMB retained ProBank Austin to serve as exclusive financial advisor in connection with evaluating and implementingCFGW’s consideration of a potential transaction involving the sale or merger of the company. ProBank Austin is an investment banking and consulting firm specializing in community bank mergers and acquisitions. IMBpossible business combination. CFGW selected ProBank AustinPiper Sandler to act as its financial advisor onbecause Piper Sandler is a nationally recognized investment banking firm with a principal business specialty advising financial institutions. In the basisordinary course of its experienceinvestment banking business, Piper Sandler is regularly engaged in the valuation of financial institutions and expertisetheir securities in representing community banks in similar transactionsconnection with mergers and its familiarity with IMB.

Piper Sandler acted as financial advisor ProBank Austin provided a fairness opinion (the “ProBank Austin Opinion”) to the IMBCFGW Board in connection with the Merger.proposed merger and participated in certain of the negotiations leading to the execution of the merger agreement. At the August 8, 2023 meeting ofat which the IMBCFGW Board on October 24, 2017, ProBank Austin renderedconsidered the merger and the merger agreement, Piper Sandler delivered to the CFGW Board its oral opinion, (whichwhich was subsequently confirmed in writing by delivery of ProBank Austin’s written opinion dated October 26, 2017) that, based upon and subjecton August 14, 2023, to the various factors, assumptions and limitations set forth in such opinion, ProBank Austin representatives’ experience as investment bankers, ProBank Austin’s work as described in such opinion and other factors ProBank Austin deemed relevant,effect that, as of such date, the Merger Consideration set forth inper share stock consideration was fair to the Agreement was fair,holders of CFGW’s common stock from a financial point of view, to the shareholders of IMB common stock. The ProBank Austin written opinion, dated October 26, 2017, is sometimes referred to herein as the ProBank Austin Opinion.

view. The full text of Piper Sandler’s opinion is attached as Appendix C to this proxy statement/prospectus. The opinion outlines the ProBank Austin Opinion, which sets forth, among other things, theprocedures followed, assumptions made, procedures followed, matters considered and qualifications and limitations on the review undertaken by Piper Sandler in rendering its opinion, is attached asAppendix C to this proxy statement/prospectus and is incorporated herein by reference.opinion. The summarydescription of the ProBank Austin Opinionopinion set forth hereinbelow is qualified in its entirety by reference to the full text of the opinion. IMBHolders of CFGW common shareholders shouldstock are urged to read the full textentire opinion carefully in connection with their consideration of the proposed merger.

Piper Sandler’s opinion carefully and in its entirety. The ProBank Austin Opinion is addressedwas directed to the IMBCFGW Board isin connection with its consideration of the merger and the merger agreement and does not constitute a recommendation to any shareholder of CFGW as to how any such shareholder should vote at any meeting of shareholders called to consider and vote upon the approval of the merger and the merger agreement. Piper Sandler’s opinion was directed only to the fairness, from a financial point of view, of the Merger Considerationper share stock consideration to the holders of IMBCFGW common stock and doesdid not constitute a recommendationaddress the underlying business decision of CFGW to any shareholder as to how such shareholder should voteengage in the merger, the form or act on any matters relating to the Merger.

The ProBank Austin Opinion was reviewed and approved by the fairness opinion committee of ProBank Austin. ProBank Austin provided its oral opinion to the IMB Board on October 24, 2017 in connection with and for the purposesstructure of the IMB Board’s evaluation of the Merger. ProBank Austin expressed no viewmerger or opinion as to any of the legal, accounting and tax matters relating to the Merger and any other transactions contemplated byin the Agreement or any terms or other aspectsmerger agreement, the relative merits of the Agreementmerger as compared to any other alternative transactions or business strategies that might exist for CFGW or the Merger. ProBank Austin expressed no opinion as to the fairness of any consideration paid in connection with the Merger to the holderseffect of any other class of securities, creditors or other constituencies of IMB or as to the underlying decision by IMB to engagetransaction in the Merger or enter into the Agreement. ProBank Austinwhich CFGW might engage. Piper Sandler also did not express any opinion as to the fairness of the amount or nature of the compensation to be received in the Mergermerger by IMB officers, directorsany officer, director or employees,employee of CFGW, or any class of such persons, if any, relative to the compensation to be received in the Mergermerger by the holders of IMB common stock.any other shareholder. Piper Sandler’s opinion was approved by Piper Sandler’s fairness opinion committee.

The description of the opinion set forth below is qualified in its entirety by reference to the opinion. You should consider the following when reading the discussion of ProBank Austin’s opinion in this document:

Piper Sandler also discussed with certain members of the senior management of CFGW and its representatives the business, financial condition, results of operations and prospects of CFGW and held similar discussions with certain members of the senior management of Glacier and its representatives regarding the business, financial condition, results of operations and prospects of Glacier. Piper Sandler noted in its entirety;

related agreements, that all of the representations and warranties contained in the Agreement aresuch agreements were true and correct in all material respects, that each partyof the parties to the Agreement willsuch agreements would perform in all material respects all of the covenants and other obligations required to be performed by such party under the Agreement,such agreements and that the closing conditions precedent in such agreements were not and would not be waived, (ii) in the Agreement are not waived.course of obtaining the necessary regulatory or third party approvals, consents and releases with respect to the merger, no delay, limitation, restriction or condition would be imposed that would have an adverse effect on CFGW, Glacier, the merger or any related transactions, and (iii) the merger and any related transactions would be consummated in accordance with the terms of the merger agreement without any waiver, modification or amendment of any material term, condition or agreement thereof and in compliance with all applicable laws and other requirements. Finally, ProBank Austin haswith CFGW’s consent, Piper Sandler relied upon the advice IMB hasthat CFGW received from its legal, accounting and tax advisors as to all legal, accounting and tax matters relating to the Mergermerger and the other transactions contemplated by the Agreement.merger agreement. Piper Sandler expressed no opinion as to any such matters.

ProBank Austin has relied, without independent verification, upon the accuracy and completeness of the information it reviewed for the purpose of rendering its opinion. ProBank Austin did not undertake any independent evaluation or appraisal of the assets and liabilities of IMB or Glacier, norPiper Sandler’s opinion was it furnished with any appraisals. ProBank Austin has not reviewed any individual credit files of IMB or Glacier, and has assumed that IMB’s and Glacier’s allowances are, in the aggregate, adequate to cover inherent credit losses. ProBank Austin’s opinion isnecessarily based on financial, economic, regulatory, market and other conditions existingas in effect on, and the information made available to Piper Sandler as of, the date ofthereof. Events occurring after the date thereof could materially affect Piper Sandler’s opinion. Piper Sandler has not undertaken to update, revise, reaffirm or withdraw its opinion. No limitations were imposed by IMB’s boardopinion or its management on ProBank Austin with respectotherwise comment upon events occurring after the date thereof. Piper Sandler expressed no opinion as to the investigations madetrading value of CFGW common stock or Glacier common stock at any time or what the procedures followedvalue of Glacier common stock would be once the shares are actually received by ProBank Austin in rendering its opinion.the holders of CFGW stock.

In rendering its opinion, ProBank AustinPiper Sandler performed a variety of financial analyses. The summary below is not a complete description of all the analyses underlying Piper Sandler’s opinion or the presentation made the following assumptions:

In connection with its opinion, ProBank Austin reviewed:

ProBank Austin also discussed with certain members of senior management of IMB the business, financial condition, results of operations and prospects of IMB, including certain operating, regulatory and other financial matters. We held similar discussions with certain members of senior management of Glacier regarding the business, financial condition, results of operations and prospects of Glacier.

The followingCFGW Board, but is a summary of the material factors considered and analyses performed and presented by ProBank Austin in connection with its opinion dated October 26, 2017.Piper Sandler. The summary doesincludes information presented in tabular format. In order to fully understand the financial analyses, these tables must be read together with the accompanying text. The tables alone do not purport to beconstitute a complete description of the financial analyses. The preparation of a fairness opinion is a complex process involving subjective judgments as to the most appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances. The process, therefore, is not necessarily susceptible to a partial analysis or summary description. Piper Sandler believes that its analyses must be considered as a whole and that selecting portions of the factors and analyses to be considered without considering all factors and analyses, or attempting to ascribe relative weights to some or all such factors and analyses, could create an incomplete view of the evaluation process underlying its opinion. Also, no company included in Piper Sandler’s comparative analyses described below is identical to CFGW or Glacier and no transaction is identical to the merger. Accordingly, an analysis of comparable companies or transactions involves complex considerations and judgments concerning differences in financial and operating characteristics of the companies and other factors that could affect the public trading values or transaction values, as the case may be, of CFGW and Glacier and the companies to which they were compared. In arriving at its opinion, Piper Sandler did not attribute any particular weight to any analysis or factor that it considered. Rather, Piper Sandler made qualitative judgments as to the significance and relevance of each analysis and factor. Piper Sandler did not form an opinion as to whether any individual analysis or factor (positive or negative) considered in isolation supported or failed to support its opinion, rather, Piper Sandler made its determination as to the fairness of the per share stock consideration to the holders of CFGW common stock on the basis of its experience and professional judgment after considering the results of all its analyses taken as a whole.

In performing its analyses, Piper Sandler also made numerous assumptions with respect to industry performance, business and economic conditions and various other matters, many of which cannot be predicted and are beyond the control of CFGW, Glacier, and Piper Sandler. The analyses performed by ProBank Austin. Capitalized terms used herein without definition shall havePiper Sandler are not necessarily indicative of actual values or future results, both of which may be significantly more or less favorable than suggested by such analyses. Piper Sandler prepared its analyses solely for purposes of rendering its opinion and provided such analyses to the meanings givenCFGW Board at its August 8, 2023 meeting. Estimates on the values of companies do not purport to such termsbe appraisals or necessarily reflect the prices at which companies or their

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securities may actually be sold. Such estimates are inherently subject to uncertainty and actual values may be materially different. Accordingly, Piper Sandler’s analyses do not necessarily reflect the value of CFGW common stock or Glacier common stock or the prices at which CFGW or Glacier common stock may be sold at any time. The analyses of Piper Sandler and its opinion were among a number of factors taken into consideration by the CFGW Board in making its determination to approve the Agreement.merger agreement and the analyses described below should not be viewed as determinative of the decision of the CFGW Board with respect to the fairness of the per share stock consideration.

Summary of Financial Terms of Agreement.TheProposed Merger Consideration and Implied Transaction Metrics.

Piper Sandler reviewed the financial terms of the Agreement provide for Glacierproposed merger. Pursuant to exchange 4,654,151 shares of its common stock for allthe terms of the common stockmerger agreement, at the effective time of IMB. Based on 203,763 shares of IMB common stock outstanding,the merger each share of IMBCFGW common stock willissued and outstanding immediately prior to the effective time of the transaction, except for certain shares as set forth in the merger agreement, shall be converted into the right to receive 22.841from Glacier (a) the per share stock consideration, plus (b) any cash in lieu of fractional shares of Glacier common stock, subject to certain adjustments.

In addition, IMB shareholders may be entitled to a special dividend immediately prior to the closingstock. Piper Sandler calculated an aggregate implied transaction value of the Merger inapproximately $80.6 million and an amount equal to the positive difference, if any, between IMB Closing Capital and the Closing Capital Requirement of $73.5 million. IMB Closing Capital will be based on IMB’s shareholders’ equity under generally accepted accounting principles, net of goodwill and other intangible assets, as adjusted by certain items. Factors that will impact IMB Closing Capital include operating

income from July 1, 2017 to the closing, normal tax distribution dividends in accordance with past practice, changes in accumulated other comprehensive income from July 1, 2017 to the closing, and certain Transaction Related Expenses. The amount of the possible special dividend cannot be calculated with a high degree of certainty at this time, and is based in part on factors outside the control of IMB.

The Agreement provides a termination right to IMB under certain circumstances if the Glacier Average Closing Price is less than $28.07implied purchase price per share unless Glacier agrees to increase the Merger Consideration to $130,642,019 through the issuance of more common shares or payment$37.13 consisting of cash consideration. Alternatively, the Agreement provides a termination right to Glacier under certain circumstances if the Glacier Average Closing Price is greater than $42.11 per share unless IMB agrees to accept a reduction in Total Stock Consideration through the issuance of fewer shares such that the value of the Merger Consideration is $195,986,299.

Based on 203,763 shares of IMB outstanding common stock, the implied exchange ratio of 22.841 and Glacier’s closing price of $37.26 on October 26, 2017, the implied value of the Merger Consideration was $173.4 million in the aggregate or $851.06 per share. In addition, IMB shareholders may receive2,136,808 shares of CFGW common stock and 86,182 options with a special cash dividend immediately prior toweighted average strike price of $22.77, based on the closing price of Glacier common stock on August 7, 2023. Based upon financial information for CFGW as of or for the Merger. Based solelylast twelve months (“LTM”) ended June 30, 2023 and the closing price of CFGW ’s common stock on August 7, 2023, Piper Sandler calculated the value of the Per Share Stock Consideration, and giving no credit to any possible special cash dividend, thefollowing implied transaction value of $173.4 million or $851.06 per share represents:

IMB Peer Analysis. ProBank Austin compared selected results of First Security Bank’s operating performance to that of 17 selected commercial banks headquartered in Montana, Idaho, Wyoming, North Dakota and South Dakota with total assets between $700 million and $1.5 billion. In addition, the selected peer banks were not part of a larger multi-bank holding company organization (ProBank Austin excluded any bank from the peer analysis that is a subsidiary of a bank holding company with more than $2.5 billion in consolidated assets). ProBank Austin considered this group of financial institutions comparable to First Security Bank on the basis of asset size and geographic location.

This peer group consisted of the following banks:metrics:

ProBank Austin noted the following selected financial measures for the peer group as compared to First Security Bank: