SUMMARY

This summary highlights selected information from this joint proxy statement/prospectus and may not contain all of the information that is important to you regarding the merger and related matters. Independent and Guaranty urge you to carefully read this entire document and the other information that is referred to in this joint proxy statement/prospectus or contained in the reports and documents incorporated by reference in this joint proxy statement/prospectus. These documents will give you a more complete description of the items for consideration at the special meeting. For more information about Independent and Guaranty, see “Where You Can Find More Information” on page [    ]. Independent and Guaranty have included page references in this summary to direct you to other places in this joint proxy statement/prospectus where you can find a more complete description of the topics that Independent and Guaranty have summarized.

The Companies (page [    ])

Independent Bank Group, Inc.

1600 Redbud Boulevard, Suite 400

McKinney, Texas 75069-3257

(972) 562-9004

www.ibtx.com

Independent, a Texas corporation, is a bank holding company registered under the Bank Holding Company Act of 1956, as amended, or the “BHC Act.” Through Independent Bank, its wholly owned subsidiary bank, which is a Texas banking association, Independent provides a wide range of relationship driven, commercial banking products and services. Independent currently operates 74 banking offices in the Dallas/North Texas area, including McKinney, Dallas, Fort Worth, and Sherman/Denison, the Austin/Central Texas area, including Austin and Waco, the Houston Texas metropolitan area and along the Colorado Front Range area, including Denver and Colorado Springs. As of June 30, 2018, on a consolidated basis, Independent had total assets of approximately $10.0 billion, total loans of approximately $7.6 billion, total deposits of approximately $7.5 billion and total shareholders’ equity of approximately $1.5 billion.

Independent’s common stock is traded on the NASDAQ under the symbol “IBTX.”

Guaranty Bancorp

1331 Seventeenth Street, Suite 200

Denver, Colorado 80202

(303) 675-1194

www.GBNK.com

Guaranty Bancorp, a Delaware corporation, is a bank holding company registered under the BHC Act and headquartered in Colorado. Guaranty’s principal business is to serve as a holding company for Guaranty Bank and Trust Company, which we refer to as “Guaranty Bank.” Guaranty Bank is the sole member of a limited liability company that holds real estate and the sole owner of an investment management firm, Private Capital Management LLC. Guaranty currently operates 32 branches and one investment management firm in Colorado. As of June 30, 2018, on a consolidated basis, Guaranty had total assets of approximately $3.8 billion, total loans of approximately $2.9 billion, total deposits of approximately $2.9 billion and total stockholders’ equity of approximately $419 million.

Proposed Merger (page [    ])

The reorganization agreement is attached to this joint proxy statement/prospectus as Appendix A. Please read the entire reorganization agreement. It is the legal document that governs the merger.

Terms of the Merger (page [    ])

The reorganization agreement provides for the merger of Guaranty with and into Independent, with Independent being the surviving corporation following the merger. Independent is the sole shareholder of Independent Bank, a Texas banking association, and Guaranty is the sole shareholder of Guaranty Bank, a Colorado banking corporation. Pursuant to the reorganization agreement, immediately following the effectiveness of the merger, Guaranty Bank will merge with and into Independent Bank, with Independent Bank being the surviving bank following the bank merger.

Merger Consideration (page [    ])

At the effective time, each share of Guaranty common stock, except for certain specified shares of Guaranty common stock owned directly by Independent or Guaranty, including shares of Guaranty common stock held in the treasury of Guaranty (other than shares of Guaranty common stock held in trust accounts, managed accounts, mutual funds and the like, or otherwise held in a fiduciary or agency capacity, that are beneficially owned by third parties or that are held directly or indirectly by Independent or Guaranty in respect of a debt previously contracted), will be converted into the right to receive 0.45 shares of Independent common stock, without interest and with cash paid in lieu of fractional shares.

As a result of the foregoing, based on the number of shares of Independent common stock and shares of Guaranty common stock (including shares of Guaranty common stock subject to certain Guaranty restricted stock awards) outstanding as of [                    ], 2018, the last date before the date of this joint proxy statement/prospectus for which it was practicable to obtain this information, we expect that Guaranty stockholders as of immediately prior to the closing of the merger will hold, in the aggregate, approximately 30% of the issued and outstanding shares of Independent common stock immediately following the closing of the merger (without giving effect to any shares of Independent common stock held by Guaranty stockholders prior to the merger).

No fractional shares of Independent common stock will be issued in the merger. In lieu of the issuance of any such fractional shares, Independent will pay to each former holder of Guaranty shares otherwise entitled to receive such fractional shares an amount of cash (rounded to the nearest whole cent) determined by multiplying (i) the average of the daily volume-weighted average sales price per Independent share on the NASDAQ, for the twenty (20) consecutive full trading days ending on and including the third trading day preceding the closing date, as reported by Bloomberg, by (ii) the fraction of an Independent share such holder would otherwise be entitled to receive pursuant to the reorganization agreement.

The implied value of the merger consideration will fluctuate as the market price of Independent common stock fluctuates before the completion of the merger. This price will not be known at the time of the Guaranty special meeting and may be more or less than the current price of Independent common stock or the price of Independent common stock at the time of the Guaranty special meeting.

Set forth below is a table showing the hypothetical implied value of the merger consideration based on a range of market prices for Independent common stock. The table does not reflect the fact that cash will be paid instead of fractional shares.

The examples above are illustrative only. The value of the merger consideration that a Guaranty stockholder actually receives will be based on the actual closing price on NASDAQ of Independent common stock upon completion of the merger, which may be outside the range of the amounts set forth above, and as a result, the actual value of the merger consideration per share of Guaranty common stock at closing may not be shown in the above table.

Treatment of Guaranty Restricted Stock Awards (page [    ])

Pursuant to the terms of the reorganization agreement, at the effective time, each Guaranty 2005 RSA, consistent with the terms of the Guaranty 2005 Equity Plan, will vest and be entitled to receive the merger consideration in respect of each vested share of Guaranty common stock subject to such Guaranty 2005 RSA, less applicable withholding taxes.

At the effective time, subject to certain exceptions, each Guaranty 2015 RSA will be converted into an Adjusted RSA with the same terms and conditions as were applicable under such Guaranty 2015 RSA immediately prior to the effective time, except as described in the following sentences. With respect to any performance-vesting Guaranty 2015 RSA, the performance-based vesting conditions applicable to such Guaranty 2015 RSA immediately prior to the effective time will not apply from and after the effective time, and such Guaranty 2015 RSA will become a service-vesting Adjusted RSA only. The Adjusted RSA will relate to the number of shares of Independent common stock equal to the product of (i) the number of shares of Guaranty common stock subject to such Guaranty 2015 RSA immediately prior to the effective time (with respect to any performance-vesting Guaranty 2015 RSA for which the performance period has not been completed as of the effective time, the number of shares shall be the target number of shares subject to such Guaranty 2015 RSA), multiplied by (ii) the exchange ratio, with any fractional shares rounded up to the next whole number of shares.

Recommendation of the Guaranty Board and Its Reasons for the Merger (page [    ])

Based on the reasons discussed elsewhere in this joint proxy statement/prospectus, the board of directors of Guaranty believes that the merger is in the best interests of Guaranty and the stockholders of Guaranty and

recommends that Guaranty stockholders vote FOR the Guaranty merger proposal, FOR the Guaranty compensation proposal and FOR the Guaranty adjournment proposal. For a discussion of the circumstances surrounding the merger and the factors considered by Guaranty’s board of directors in approving the reorganization agreement, see the discussion beginning on page [    ].

Recommendation of the Independent Board and Its Reasons for the Merger (page [    ])

Based on the reasons discussed elsewhere in this joint proxy statement/prospectus, the board of directors of Independent believes that the merger is in the best interests of Independent and the shareholders of Independent and recommends that Independent shareholders vote FOR the Independent merger proposal and FOR the Independent adjournment proposal. For a discussion of the circumstances surrounding the merger and the factors considered by Independent’s board of directors in approving the reorganization agreement, see the discussion beginning on page [    ].

Opinion of Guaranty’s Financial Advisor (page [    ]; Appendix C)

In connection with the merger, Guaranty’s financial advisor, Keefe, Bruyette & Woods, Inc. (“KBW”), delivered a written opinion, dated May 22, 2018, to the Guaranty board of directors as to the fairness, from a financial point of view and as of the date of the opinion, to the holders of Guaranty common stock of the exchange ratio in the proposed merger. The full text of the opinion, which describes the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW in preparing the opinion, is attached as Appendix C to this joint proxy statement/prospectus. The opinion was for the information of, and was directed to, the Guaranty board (in its capacity as such) in connection with its consideration of the financial terms of the merger. The opinion did not address the underlying business decision of Guaranty to engage in the merger or enter into the reorganization agreement or constitute a recommendation to the Guaranty board of directors in connection with the merger, and it does not constitute a recommendation to any holder of Guaranty common stock or any stockholder of any other entity as to how to vote in connection with the merger or any other matter.

Fairness Opinion Provided to Independent (page [    ]; Appendix B)

Stephens Inc., or “Stephens,” has delivered a written opinion, dated May 22, 2018, to the board of directors of Independent that, as of the date of the reorganization agreement, based upon and subject to certain matters stated in the opinion, the consideration to be paid in the merger by Independent is fair, from a financial point of view, to Independent. This opinion is attached to this joint proxy statement/prospectus as Appendix B. The opinion of Stephens is not a recommendation to any Independent shareholder as to how to vote on the Independent merger proposal. You should read this opinion completely to understand the procedures followed, matters considered and limitations on the reviews undertaken by Stephens in providing its opinion.

Financial Interests of Directors and Officers of Guaranty in the Merger (page [    ])

Guaranty’s executive officers and directors may have interests in the merger that are different from, or in addition to, the interests of Guaranty’s stockholders generally. Such interests include payments in connection with employment agreements with certain executive officers, Independent and Independent Bank entering into a new employment agreement with one of Guaranty Bank’s executive officers, payments made in connection with a change in control severance plan and the right to indemnification and insurance coverage following the consummation of the merger. The members of the Guaranty board of directors were aware of and considered these interests, among other matters, when they approved the reorganization agreement and recommended that Guaranty stockholders approve the Guaranty merger proposal. These interests are described in more detail under the section entitled “The Merger—Financial Interests of Directors and Officers of Guaranty in the Merger” beginning on page [    ].

The Independent Board of Directors After the Merger (page [    ])

Effective immediately after the effective time, Independent will appoint Edward B. Cordes, Guaranty’s current Chairman, and Paul W. Taylor, Guaranty’s current President and Chief Executive Officer, to the Independent board of directors, each for a term expiring at the next annual meeting of the shareholders of Independent following the effective time. Independent will also nominate, and recommend that Independent shareholders elect, each of Mr. Cordes and Mr. Taylor as a Class III director at the 2019 annual meeting of Independent shareholders, subject to each nominee’s compliance with Independent’s governance and ethics policies in place from time to time, as reasonably determined by Independent’s Corporate Governance and Nominating Committee.

Independent Plans to Continue Payment of Quarterly Dividends (page [    ])

As approved by Independent’s board of directors, Independent declared and paid a $0.08 per share dividend to holders of Independent common stock in the first three fiscal quarters of 2016 and a $0.10 per share dividend paid in the fourth fiscal quarter of 2016 and in each fiscal quarter of 2017, a $0.12 per share dividend to holders of Independent common stock in the first fiscal quarter of 2018 and a $0.14 per share dividend in the second fiscal quarter of 2018. On July 25, 2018, Independent declared a quarterly cash dividend in the amount of $0.14 per share of common stock.

Independent intends to continue to pay regular quarterly cash dividends on its common stock in the fourth fiscal quarter of 2018 and following the merger, when, as and if declared by Independent’s board of directors out of funds legally available for that purpose and subject to regulatory restrictions.

Issued Independent Shares Will Be Eligible for Trading (page [    ])

Independent shares are listed for trading on the NASDAQ under the symbol “IBTX” and Guaranty common stock is listed for trading on the NASDAQ under the symbol “GBNK.” Upon completion of the merger, Guaranty common stock will no longer be listed for trading on the NASDAQ.

Under the reorganization agreement, Independent has agreed to file all documents required to be filed to have the shares of Independent common stock to be issued approved for listing on the NASDAQ prior to closing and to use its commercially reasonable efforts to effect such listing. The obligations of the parties to complete the merger are subject to such shares having been approved for listing on the NASDAQ and such approval having not been withdrawn or revoked.

Market Prices of Independent and Guaranty Common Stock (page [    ])

On May 21, 2018, the last trading day before the merger was announced, Independent common stock closed at $78.60 per share. On [                    ], 2018, the last practicable date before the date of this joint proxy statement/prospectus, Independent common stock closed at $[        ] per share.

On May 21, 2018, the last trading day before the merger was announced, Guaranty common stock closed at $30.70 per share. On [                    ], 2018, the last practicable date before the date of this joint proxy statement/prospectus, Guaranty common stock closed at $[        ] per share.

The market price of Independent common stock and Guaranty common stock will fluctuate prior to the merger. You should obtain the most recent closing price for Independent common stock and Guaranty common stock on the NASDAQ prior to deciding how to vote.

Dissenters’ Rights (page [    ])

Under applicable Delaware law, holders of Guaranty common stock are not entitled to dissenters’ or appraisal rights in connection with the merger. Under the TBOC, the holders of shares of Independent common stock are not entitled to dissenters’ or appraisal rights in connection with the merger or the share issuance in connection with the merger.

Regulatory Approvals Required for the Merger (page [    ])

The acquisition of Guaranty and Guaranty Bank by Independent requires the approval of the Federal Reserve. The bank merger requires the approval of the FDIC and the Texas Department of Banking (which we refer to as the “TDB”). The acquisition of Guaranty and Guaranty Bank by Independent and Independent Bank requires the approval of the Colorado State Banking Board (which we refer to as the “CSBB”). On June 28, 2018, Independent filed the required application with the Federal Reserve and Independent Bank and Guaranty Bank filed the required applications with the FDIC and TDB. On June 29, 2018, Independent and Independent Bank filed the required application with the CSBB.

Exchange Procedures (page [    ])

After the effective time of the merger, the Guaranty stockholders will receive a letter of transmittal and instructions from EQ Shareowner Services, acting as Independent’s exchange and transfer agent, or the exchange agent, describing the procedures for surrendering their certificate or certificates representing shares of Guaranty common stock (which we refer to as a “Guaranty certificate,” which is deemed to include reference to book-entry accounts relating to the ownership of shares of Guaranty common stock).

When you properly surrender your Guaranty certificates or provide other satisfactory evidence of ownership, and return the letter of transmittal duly executed and completed in accordance with its instructions, EQ Shareowner Services will promptly cancel the surrendered stock certificates and deliver to you a notice specifying, among other things, the number of shares of Independent common stock, which will be solely in uncertificated book-entry form credited to the account of the holder of record as established in the Direct Registration System, and cash for fractional shares, if any, to which you are entitled under the reorganization agreement. No Independent stock certificates will be issued with respect to the Independent common stock to be issued under the reorganization agreement.

Please do not send Guaranty or Independent any of your Guaranty stock certificates until you receive these instructions, which will be as soon as practicable after the effective time.

Effective Time of the Merger (page [    ])

The merger will become effective at the date and time specified in the certificate of merger to be filed with the Secretary of State of Texas and the certificate of merger to be filed with the Secretary of State of Delaware, which is expected to be 12:01 a.m. on the first day of the calendar month immediately following the calendar month in which all conditions are satisfied or (subject to applicable law) waived (other than conditions that by their nature can only be satisfied at the closing, but subject to the satisfaction or waiver thereof). It is anticipated that the bank merger will be effective immediately thereafter. If the shareholders of Guaranty and Independent approve and adopt the reorganization agreement at their respective special meetings, it is currently anticipated that the completion of the merger will occur in the fourth quarter of 2018, but completion of the merger could be delayed if there is a delay in obtaining the required regulatory approvals or in satisfying any other conditions to the merger.

Independent and Guaranty cannot assure you that the necessary shareholder and regulatory approvals will be obtained or that the other conditions to completion of the merger can or will be satisfied. See “Risk Factors—

Risks Related to the Merger—The merger of Independent and Guaranty may not be completed, may take longer than expected or may be subject to conditions imposed by government entities that are not presently anticipated or cannot be met.”

Conditions to Completion of the Merger (page [    ])

The reorganization agreement contains a number of customary conditions to the obligations of Independent and Guaranty to complete the merger that must be satisfied as of the closing date, including the approval and adoption of the reorganization agreement by the requisite Independent shareholder vote and the requisite Guaranty stockholder vote, as well as the receipt of all required regulatory approvals.

Any condition to the completion of the merger may, to the extent permitted by law, be waived in writing by the party or parties to the reorganization agreement entitled to the benefit of such condition.

No Negotiation with Others (page [    ])

Pursuant to the reorganization agreement, Guaranty agreed that it will not, and that it will cause each Guaranty subsidiary and the respective employees, directors, officers, financial advisors, agents and other representatives of Guaranty and each Guaranty subsidiary (which we collectively refer to as the “Guaranty representatives”) not to (i) solicit, knowingly encourage or facilitate, initiate or participate in any negotiations or discussions with any third party (except for the limited purpose of notifying such person of the existence of the non-solicitation provisions of the reorganization agreement) regarding an acquisition proposal, whether by acquisition, business combination, purchase of securities or assets or otherwise; (ii) disclose to any third party any information concerning the business, properties, books or records of Guaranty or any Guaranty subsidiary in connection with any acquisition proposal; or (iii) cooperate with any third party to make any acquisition proposal. Promptly upon receipt of any unsolicited offer, Guaranty will communicate to Independent the terms of any proposal or request for information and the identity of the parties involved.

Provided that it has complied with the foregoing provisions, if at any time after the date of the reorganization agreement and before the receipt of the requisite Guaranty stockholder approval, Guaranty and the Guaranty representatives receives a bona fide, unsolicited written acquisition proposal, Guaranty and the Guaranty representatives may engage in negotiations and discussions with, and furnish any information and other access (so long as all such information and access has previously been made available to Independent or is made available to Independent before or concurrently with the time such information or access is made available to such person) to, any person making such acquisition proposal if, and only if, the Guaranty board of directors determines in good faith, after consultation with outside legal and financial advisors, that (i) such acquisition proposal constitutes or is reasonably likely to become a superior proposal and (ii) the failure of the Guaranty board of directors to furnish such information or access or enter into such discussions or negotiations would be inconsistent with its fiduciary duties under applicable law; provided that before furnishing any such information, Guaranty has received from the person making such acquisition proposal an executed confidentiality agreement with terms at least as restrictive in all material respects on such person as the confidentiality agreement entered into with Independent, which confidentiality agreement may not prohibit Guaranty from complying with the terms of the reorganization agreement.

Termination of the Reorganization Agreement (page [    ])

Independent and Guaranty can mutually agree at any time to terminate the reorganization agreement without completing the merger. In addition, either Independent or Guaranty may terminate the reorganization agreement as follows:

In addition, Guaranty may terminate the reorganization agreement:

If Guaranty elects to exercise its termination right pursuant to this provision it must give written notice to Independent. Following its receipt of such notice, Independent will have the option, at its sole discretion, to increase the consideration to be received by the Guaranty stockholders by adjusting the exchange ratio (calculated to the nearest ten-thousandth) to a number (rounded to the nearest ten-thousandth) equal to the quotient of (A) the product of (i) the product of $78.60, multiplied by 0.85, multiplied by (ii) the exchange ratio,

divided by (B) the average of the daily volume-weighted average sales price per Independent share on the NASDAQ for the twenty (20) consecutive full trading days ending on and including the third trading day preceding the closing date, as reported by Bloomberg. If Independent so elects, it will give prompt written notice to Guaranty of such election and the revised exchange ratio, whereupon no termination will have occurred pursuant to this provision and the reorganization agreement will remain in effect in accordance with its terms (except as the exchange ratio has been so modified).

In addition, Independent may terminate the reorganization agreement:

Termination Fee (page [    ])

Guaranty will pay Independent a $40 million termination fee if the reorganization agreement is terminated in the following circumstances:

Independent will pay Guaranty a $40 million termination fee if the reorganization agreement is terminated by Guaranty because Independent or the Independent board of directors has failed to comply in any material respect with its obligations described under “The Reorganization Agreement—Independent Shareholder Meeting and Recommendation of the Independent Board of Directors.”

Amendment or Waiver of the Reorganization Agreement (page [    ])

Independent and Guaranty may amend the reorganization agreement and each party may waive its right to require the other party to adhere to any term or satisfy any condition of the reorganization agreement in accordance with the terms of the reorganization agreement. However, after the approval and adoption of the reorganization agreement by the Guaranty stockholders and Independent shareholders, there may not be any

amendment that requires further approval of such stockholders or shareholders, as applicable, under applicable law, without obtaining such approval.

Voting Agreements (page [    ])

Each of the directors of Guaranty and certain entities they represent have entered into a voting agreement with Independent and Guaranty, solely in their capacities as stockholders of Guaranty, pursuant to which they have agreed, among other things, to vote in favor of the Guaranty merger proposal, the Guaranty compensation proposal and the Guaranty adjournment proposal, and against any alternative acquisition proposal, as well as certain other customary restrictions with respect to the voting and (other than the voting agreements executed by certain private equity-affiliated directors of Guaranty) transfer of his or her shares of Guaranty common stock. As of [                    ], 2018, the record date for the Guaranty special meeting, Guaranty stockholders who are parties to the Guaranty voting agreements beneficially owned and were entitled to vote approximately [            ] shares of Guaranty common stock representing approximately [    ]% of the shares of Guaranty common stock outstanding on that date.

Each of the directors of Independent, along with Mr. Vincent J. Viola, who is the largest shareholder of Independent and the father of Mr. Michael T. Viola, a director of Independent, have entered into a voting agreement with Guaranty and Independent, solely in their capacities as shareholders of Independent, pursuant to which they have agreed, among other things, to vote in favor of the Independent merger proposal and the Independent adjournment proposal, as well as certain other customary restrictions with respect to the voting of his or her shares of Independent common stock. As of [                    ], 2018, the record date for the Independent special meeting, Independent shareholders who are parties to the Independent voting agreements beneficially owned and were entitled to vote approximately [            ] shares of Independent common stock representing approximately [    ]% of the shares of Independent common stock outstanding on that date.

Material U.S. Federal Income Tax Consequences of the Merger (page [    ])

The merger is intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Code, and it is a condition to the respective obligations of Independent and Guaranty to complete the merger that each of Independent and Guaranty receives a legal opinion to that effect. Accordingly, holders of Guaranty common stock are not expected to recognize any gain or loss for U.S. federal income tax purposes on the exchange of shares of Guaranty common stock for shares of Independent common stock in the merger, except with respect to any cash received instead of fractional shares of Independent common stock. For further information, please refer to “Material U.S. Federal Income Tax Consequences of the Merger.” The U.S. federal income tax consequences described above may not apply to all holders of Guaranty common stock. The tax consequences to a holder of Guaranty common stock will depend on his or her individual situation. Accordingly, we strongly urge holders of Guaranty common stock to consult their tax advisors for a full understanding of the particular tax consequences of the merger to them.

Accounting Treatment (page [    ])

The merger will be accounted for as an acquisition of Guaranty and Guaranty Bank by Independent and Independent Bank under the acquisition method of accounting in accordance with the Financial Accounting Standard Board’s Accounting Standard Codification Topic 805, “Business Combinations.”

The Guaranty Special Meeting (page [    ])

The special meeting of stockholders of Guaranty will be held on [                    ], 2018, at [    ] Mountain Time, at [    ]. At the Guaranty special meeting, Guaranty’s stockholders will be asked to consider and vote on the following:

You may vote on the proposals to come before special meeting of Guaranty stockholders if you owned shares of Guaranty common stock of record as of the record date. You can cast one vote for each share of Guaranty common stock that you owned of record at that time. As of the record date, there were [            ] shares of Guaranty common stock outstanding.

At the close of business on the record date for the Guaranty special meeting, Guaranty directors and executive officers and their respective affiliates were entitled to vote approximately [            ] shares of Guaranty common stock, or approximately [    ]% of the shares of Guaranty common stock outstanding on that date.

Guaranty Proposals: Required Vote and Treatment of Abstentions and Failure to Vote (page [    ])

The Guaranty merger proposal requires the affirmative vote of the holders of at least a majority of the issued and outstanding shares of Guaranty common stock entitled to vote at the Guaranty special meeting. Failures to vote, broker nonvotes and abstentions will have the same effect as a vote against this proposal.

The Guaranty compensation proposal requires the affirmative vote of a majority of the votes cast by the Guaranty stockholders entitled to vote on such proposal at the Guaranty special meeting. Failures to vote, broker nonvotes and abstentions will have no effect on the vote for the proposal.

The Guaranty adjournment proposal requires the affirmative vote of a majority of votes cast by the Guaranty stockholders entitled to vote on such proposal at the Guaranty special meeting. Failures to vote, broker nonvotes and abstentions will have no effect on the vote for the proposal.

A holder of Guaranty common stock may vote his or her shares of Guaranty common stock by attending the special meeting and voting in person, by completing and mailing the enclosed proxy card, or by following the instructions to vote via the Internet or by telephone as indicated on the proxy card and elsewhere in this joint proxy statement/prospectus. If you are the record holder of such shares, you can revoke your proxy at any time before the vote is taken at the Guaranty special meeting by sending a written notice revoking the proxy or submitting a later-dated proxy to Guaranty Bancorp, Attention: Corporate Secretary, 1331 Seventeenth Street, Suite 200, Denver, Colorado 80202, which notice or later-dated proxy must be received no later than immediately prior to the vote at the Guaranty special meeting, or by logging onto the Internet website specified on your proxy card in the same manner you would to submit your proxy electronically or by calling the telephone number specified on your proxy card, in each case if you are eligible to do so, and following the instructions indicated on the proxy card prior to 11:59 p.m. Mountain Time, on [                    ], 2018. You may also revoke your proxy by voting in person at the Guaranty special meeting. If your shares of Guaranty common stock are held in “street name” and you desire to change any voting instructions you have previously given to the record holder of such shares of Guaranty common stock of which you are the beneficial owner, you should contact the broker, bank, trustee or other nominee holding such shares in “street name” in order to direct a change in the manner your shares of Guaranty common stock will be voted. See “The Guaranty Special Meeting—Voting of Proxies by Holders of Record,” “—Attending the Meeting; Voting in Person” and “—Revocation of Proxies.”

The Independent Special Meeting (page [    ])

The special meeting of shareholders of Independent will be held on [                    ], 2018, at [    ] Central Time, at [    ]. At the Independent special meeting, Independent’s shareholders will be asked to consider and vote on the following:

You may vote at the special meeting of Independent shareholders if you owned Independent common stock of record as of the record date. You can cast one vote for each share of Independent common stock you owned of record at that time. As of the record date, there were [            ] shares of Independent common stock outstanding.

At the close of business on the record date for the Independent special meeting, Independent directors and executive officers and their respective affiliates were entitled to vote approximately [            ] shares of Independent common stock, or approximately [    ]% of the shares of Independent common stock outstanding on that date. In addition, Mr. Vincent J. Viola, who is the largest shareholder of Independent and the father of Mr. Michael T. Viola, a director of Independent, owned approximately [            ] shares of Independent common stock as of the close of business on the record date for the Independent special meeting.

Independent Proposals: Required Vote and Treatment of Abstentions and Failure to Vote (page [    ])

The required votes to approve the Independent proposals are as follows:

The Independent merger proposal requires the affirmative vote of the holders of at least two-thirds of the issued and outstanding shares of Independent common stock entitled to vote at the Independent special meeting. Failures to vote, broker nonvotes and abstentions will have the same effect as a vote against this proposal.

The Independent adjournment proposal requires the affirmative vote of a majority of votes cast by the Independent shareholders entitled to vote on such proposal at the Independent special meeting. Failures to vote, broker nonvotes and abstentions will have no effect on the vote for the proposal.

You may vote your shares of Independent common stock by attending the special meeting and voting in person, by completing and mailing the enclosed proxy card or by following the instructions to vote via the Internet or by telephone as indicated on the proxy card and elsewhere in this joint proxy statement/prospectus. If you are the record holder of your shares, you can revoke your proxy at any time before the vote is taken at the Independent special meeting by sending a written notice revoking the proxy or submitting a later dated proxy to the Corporate Secretary of Independent, which must be received no later than immediately prior to the vote at the Independent special meeting, or by logging onto the Internet website specified on your proxy card in the same manner you would to submit your proxy electronically or by calling the telephone number specified on your proxy card, in each case if you are eligible to do so, and following the instructions indicated on the proxy card prior to 11:59 p.m. Central Time, on [                    ], 2018. You may also revoke your proxy by voting in person at the Independent special meeting. If your shares of Independent common stock are held in “street name” and you desire to change any voting instructions you have previously given to the record holder of the shares of which you are the beneficial owner, you should contact the broker, bank, trustee or other nominee holding your shares in “street name” in order to direct a change in the manner your shares will be voted. See “The Independent Special Meeting—Voting of Proxies by Holders of Record,” “—Attending the Meeting; Voting in Person” and “—Revocation of Proxies.”

Comparison of Rights of Shareholders of Guaranty and Independent (page [    ])

Guaranty is a Delaware corporation that is a registered bank holding company, and the rights of stockholders of Guaranty are governed by Delaware law and Guaranty’s certificate of incorporation and bylaws. Independent is a Texas corporation that is a registered bank holding company, and the rights of Independent’s shareholders are governed by Texas law and Independent’s certificate of formation and bylaws. Upon completion of the merger, Guaranty stockholders will become shareholders of Independent and their rights as shareholders of Independent will be governed by Independent’s certificate of formation and bylaws, in addition to Texas law. Independent’s certificate of formation and bylaws will not be amended in the merger, but could be later restated, amended or, with respect to the bylaws, repealed.

CERTAIN FINANCIAL INFORMATION REGARDING INDEPENDENT AND GUARANTY

Selected Financial Information of Independent

The following selected historical consolidated financial information of Independent as of and for the six months ended June 30, 2018 and June 30, 2017, has been derived from Independent’s unaudited consolidated financial statements as of and for the six months ended June 30, 2018 and June 30, 2017, respectively, incorporated by reference in this joint proxy statement/prospectus. The following selected consolidated financial information of Independent as of and for the years ended December 31, 2017, 2016 and 2015, has been derived from Independent’s audited consolidated financial statements incorporated by reference in this joint proxy statement/prospectus, and the selected consolidated financial information as of and for the years ended December 31, 2014 and 2013, has been derived from Independent’s audited consolidated financial statements not appearing or incorporated by reference in this joint proxy statement/prospectus.

You should read the following financial information relating to Independent in conjunction with other information contained in this joint proxy statement/prospectus, including consolidated financial statements of Independent and related accompanying notes appearing in Independent’s Annual Report on Form 10-K most recently filed with the SEC and in the Quarterly Reports on Form 10-Q of Independent filed with the SEC after that Annual Report on Form 10-K was filed, and in any Current Report on Form 8-K of Independent containing consolidated financial statements of Independent that was filed with the SEC after such Annual Report on Form 10-K, each of which reports is incorporated by reference in this joint proxy statement/prospectus. Independent’s historical results for any prior period are not necessarily indicative of results to be expected in any future period, and Independent’s historical results for the six months ended June 30, 2018, are not necessarily indicative of its results to be expected for all of 2018. Independent has consummated several acquisitions in recent fiscal periods. The results and other financial information of those acquired operations are not included in the table below for the periods or dates prior to their respective acquisition dates and, therefore, the results for these prior periods are not comparable in all respects and may not be predictive of Independent’s future results. In addition, the selected financial information in the table immediately below does not include, on any basis, the results or financial condition of Guaranty for any period or as of any date.

Reconciliations of Non-GAAP Financial Measures

The following information reconciles: (i) Independent’s tangible book value per common share, a non-GAAP financial measure, as of the dates presented to Independent’s book value per common share, a financial measure calculated and presented in accordance with GAAP, as of the dates presented; and (ii) its ratio of tangible common equity to tangible assets, a non-GAAP financial measure, as of the dates presented to Independent’s ratio of total common equity to total assets, a financial measure calculated and presented in accordance with GAAP, as of the dates presented.

Selected Financial Information of Guaranty

The following selected historical consolidated financial information of Guaranty as of and for the six months ended June 30, 2018 and June 30, 2017, has been derived from Guaranty’s unaudited consolidated financial statements as of and for the six months ended June 30, 2018 and June 30, 2017, incorporated by reference in this joint proxy statement/prospectus. The following selected consolidated financial information of Guaranty as of and for the years ended December 31, 2017, 2016 and 2015 has been derived from Guaranty’s audited consolidated financial statements incorporated by reference in this joint proxy statement/prospectus, and the selected consolidated financial information as of and for the years ended December 31, 2014 and 2013 has been derived from Guaranty’s audited consolidated financial statements not appearing or incorporated by reference in this joint proxy statement/prospectus.

You should read the following financial information relating to Guaranty in conjunction with other information contained in this joint proxy statement/prospectus or incorporated by reference, including the consolidated financial statements of Guaranty and related accompanying notes appearing in Guaranty’s Annual Report on Form 10-K most recently filed with the SEC and in the Quarterly Reports on Form 10-Q of Guaranty filed with the SEC after that Annual Report on Form 10-K was filed, and in any Current Report on Form 8-K of Guaranty containing consolidated financial statements of Guaranty that was filed with the SEC after such Annual Report on Form 10-K, each of which reports is incorporated by reference in this joint proxy statement/

prospectus. Guaranty’s historical results for any prior period are not necessarily indicative of results to be expected in any future period, and Guaranty’s historical results for the six months ended June 30, 2018, are not necessarily indicative of its results to be expected for all of 2018. Guaranty has consummated multiple acquisitions in recent fiscal periods. The results and other financial information of those acquired operations are not included in the table below for the periods or dates prior to their respective acquisition dates and, therefore, the results for these prior periods are not comparable in all respects and may not be predictive of Guaranty’s future results.

Please see the section entitled “Where You Can Find More Information” for instructions on how to obtain the information that has been incorporated by reference. You should not assume the results of operations for past years indicate results for any future period.

Unaudited Pro Forma Combined Financial Information

Independent has prepared the unaudited pro forma consolidated income statements appearing below to present on a pro forma basis the consolidated income statements of Independent assuming that the merger with Guaranty was consummated on January 1, 2017, and assuming that Independent’s acquisition of Carlile Bancshares, Inc., which we refer to as “Carlile Bancshares,” was consummated on January 1, 2017, and to provide information with respect to the pro forma consolidated results of operations that Independent would have had for the year ended December 31, 2017, and the six months ended June 30, 2018, had the merger with Guaranty been consummated on January 1, 2017 and had Independent’s acquisition of Carlile Bancshares been consummated on January 1, 2017. Independent has prepared the unaudited pro forma combined balance sheet appearing below to present on a pro forma basis the consolidated financial position of Independent assuming that the merger with Guaranty was consummated on June 30, 2018. The merger of Independent and Guaranty will be accounted for as an acquisition of Guaranty and Guaranty Bank by Independent and Independent Bank under the acquisition method of accounting in accordance with the Financial Accounting Standard Board’s Accounting Standard Codification Topic 805, “Business Combinations.” The unaudited pro forma combined financial statements of Independent and the other pro forma combined financial information appearing below have been prepared using the acquisition method of accounting.

Independent has not had sufficient time to completely evaluate the significant identifiable long-lived tangible and identifiable intangible assets of Guaranty. Accordingly, the unaudited pro forma adjustments, including the allocations of the purchase price, are preliminary and have been made solely for the purpose of providing unaudited pro forma combined financial information. Certain reclassifications have been made to the historical financial statements of Guaranty to conform to the presentation in Independent’s financial statements. Accordingly, the unaudited pro forma combined financial statements and other unaudited pro forma combined financial information are presented for illustrative purposes only and are not necessarily indicative of the results that might have occurred had the merger taken place on January 1, 2017, for statement of income purposes and on June 30, 2018, for balance sheet purposes, and is not intended to be a projection of future results. Historical results for any prior period are not necessarily indicative of results to be expected in any future period, and historical results for the six months ended June 30, 2018, are not necessarily indicative of results to be expected for all of 2018. A final determination of the acquisition consideration and fair values of Guaranty’s assets and liabilities, which cannot be made prior to the completion of the merger, will be based on the actual net tangible and intangible assets of Guaranty that exist as of the date of completion of the transaction. Consequently, amounts preliminarily allocated to goodwill and identifiable intangibles could change significantly from those allocations used in the unaudited pro forma combined financial statements presented below and could result in a material change in amortization of acquired intangible assets.

In connection with the plan to integrate the operations of Independent and Guaranty following the completion of the merger, Independent anticipates that nonrecurring charges, such as costs associated with systems implementation, severance, and other costs related to exit or disposal activities, could be incurred. Independent is not able to determine the timing, nature and amount of these charges as of the date of this joint proxy statement/prospectus. However, these charges could affect the results of operations of Independent and Guaranty, as well as those of the combined company following the completion of the merger, in the period in which they are recorded. The unaudited pro forma combined financial statements do not include the effects of the costs associated with any restructuring or integration activities resulting from the transaction, as they are nonrecurring in nature and not factually supportable at the time that the unaudited pro forma combined financial statements were prepared. Additionally, the unaudited pro forma adjustments do not give effect to any nonrecurring or unusual restructuring charges that may be incurred as a result of the integration of the two companies or any anticipated disposition of assets that may result from such integration. Direct transaction related expenses estimated at $1.65 million for Independent and $9.6 million for Guaranty are not included in the unaudited pro forma consolidated income statements.

In addition, future results may differ materially from the results reflected because of various factors, including those discussed in the section entitled “Risk Factors” beginning on page 44 and appearing under the caption “Risk Factors” in Independent’s and Guaranty’s most recently filed Annual Reports on Form 10-K and in any subsequently filed Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, which are incorporated by reference in this joint proxy statement/prospectus, and the factors discussed under the caption “Cautionary Note Regarding Forward-Looking Statements” appearing elsewhere in this joint proxy statement/prospectus. Among other factors, the actual amounts recorded as of the completion of the merger may differ materially from the information presented in these unaudited pro forma combined financial statements as a result of:

The unaudited pro forma combined financial statements are provided for information purposes only. The unaudited pro forma combined financial statements are not necessarily, and should not be assumed to be, an indication of the results that would have been achieved had the transaction been completed as of the dates indicated or that may be achieved in the future. The preparation of the unaudited pro forma combined financial statements and related adjustments required management to make certain assumptions and estimates. The unaudited pro forma combined financial statements should be read together with:

The unaudited pro forma combined income statement data for the year ended December 31, 2017 and for the six months ended June 30, 2018 presents the consolidated results of operations giving pro forma effect to the following transactions as if they had occurred as of January 1, 2017:

The unaudited pro forma combined income statement data does not give pro forma effect to Independent’s acquisition of Integrity Bancshares, Inc., which was consummated on June 1, 2018, for any period prior to the date of consummation.

The unaudited pro forma combined balance sheet as of June 30, 2018 presents the consolidated financial position giving pro forma effect to the following transactions as if they had occurred as of June 30, 2018:

Pro Forma Consolidated Income Statement

(Unaudited)