Compass Therapeutics : 2024 Proxy

• Preliminary Proxy Statement
• Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
• Definitive Proxy Statement
• Definitive Additional Materials
• Soliciting Material Pursuant to §240.14a-12

Compass Therapeutics, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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COMPASS THERAPEUTICS, INC.

80 Guest Street, Suite 601

Boston, MA 02135

NOTICE OF 2024 ANNUAL MEETING OF STOCKHOLDERS TO BE HELD JUNE 13, 2024

Notice is hereby given that the 2024 Annual Meeting of Stockholders (the "Annual Meeting") of Compass Therapeutics, Inc. will be held on June 13, 2024, at 10:00 a.m. Eastern Time. The Annual Meeting will be a virtual meeting. You will be able to attend and participate in the Annual Meeting online by registering at www.virtualshareholdermeeting.com/CMPX2024.

We are pleased to take advantage of Securities and Exchange Commission rules that allow companies to furnish their proxy materials over the Internet. We are mailing to our stockholders a Notice of Internet Availability of Proxy Materials (the "Notice"), instead of a paper copy of our proxy materials and our 2023 Annual Report to Stockholders (the "2023 Annual Report"). The Notice contains instructions on how to access those documents and to cast your vote via the Internet. The Notice also contains instructions on how to request a paper copy of our proxy materials and our 2023 Annual Report. This process allows us to provide our stockholders with necessary information on a more timely basis, while reducing the environmental impact and lowering the costs of printing and distributing our proxy materials.

The purpose of the Annual Meeting is the following:

1. To elect two class I directors to our Board of Directors, to serve until the 2027 annual meeting of stockholders and until his or her successor has been duly elected and qualified, or until his or her earlier death, resignation or removal;
2. To ratify the appointment of CohnReznick LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2024; and
3. To transact any other business properly brought before the Annual Meeting or any adjournment or postponement of the Annual Meeting.

Only Compass Therapeutics, Inc. stockholders of record at the close of business on April 17, 2024, will be entitled to vote at the Annual Meeting and any adjournment or postponement thereof.

To be admitted to the Annual Meeting and vote your shares, you must register at www.virtualshareholdermeeting.com/CMPX2024. You will be required to enter the control number provided on your proxy card, and beneficial owners of shares held in street name will need to follow the instructions provided in the voting instructions form by the broker, bank or other nominee that holds their shares. Upon completing your registration, you will receive further instructions via email, including unique links to access the Annual Meeting and to submit questions in advance of the Annual Meeting. Please see the "General Information" section of the proxy statement that accompanies this notice for details regarding the logistics of the virtual Annual Meeting, including the ability of stockholders to submit questions during the Annual Meeting.

Your vote is important. Whether or not you are able to attend the Annual Meeting, it is important that your shares be represented. To ensure that your vote is recorded promptly, please vote as soon as possible, even if you plan to attend the Annual Meeting, by submitting your proxy by telephone or via the Internet at the address listed on the proxy card or by signing, dating and returning the proxy card.

By order of our Board of Directors,

Vered Bisker-Leib, Ph.D., M.B.A.

Chief Executive Officer

Boston, Massachusetts

April 29, 2024

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Stockholders are requested to sign the enclosed proxy card and return it in the enclosed stamped envelope by return mail.

-OR-

Stockholders may also complete a proxy via the Internet (www.proxyvote.com) or by telephone (1-800-690-6903) in accordance with the instructions listed on the proxy card.

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Table of Contents

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COMPASS THERAPEUTICS, INC.

80 GUEST STREET, SUITE 601

BOSTON, MA 02135

PROXY STATEMENT

FOR THE 2024 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD JUNE 13, 2024

This proxy statement contains information about the 2024 Annual Meeting of Stockholders (the "Annual Meeting") of Compass Therapeutics, Inc., which will be held on June 13, 2024 at 10:00 a.m. Eastern Time. The Annual Meeting will be a virtual meeting. You will be able to attend and participate in the Annual Meeting online by registering at www.virtualshareholdermeeting.com/CMPX2024.

The Board of Directors of Compass Therapeutics, Inc. is using this proxy statement to solicit proxies for use at the Annual Meeting. In this proxy statement, the terms "Compass," "we," "us," and "our" refer to Compass Therapeutics, Inc. The mailing address of our principal executive offices is Compass Therapeutics, Inc., 80 Guest Street, Suite 601, Boston, MA 02135.

Only Compass Therapeutics, Inc. stockholders of record at the close of business on April 17, 2024, will be entitled to vote at the Annual Meeting and any adjournment or postponement thereof. All stockholders as of the record date, or their duly appointed proxies, may attend the meeting.

To be admitted to the Annual Meeting and vote your shares, you must register at www.virtualshareholdermeeting.com/CMPX2024. You will be required to enter the control number provided on the proxy card and beneficial owners of shares held in street name will need to follow the instructions provided in the voting instructions form by the broker, bank or other nominee that holds their shares. Upon completing your registration, you will receive further instructions via email, including unique links to access the Annual Meeting and to submit questions in advance of the Annual Meeting. Please see the "General Information" section of the proxy statement for more details regarding the logistics of the virtual Annual Meeting, including the ability of stockholders to submit questions during the Annual Meeting, and technical details and support related to accessing the virtual platform.

If you are a stockholder of record, you can vote by proxy over the Internet (www.proxyvote.com) or by telephone (1-800-690-6903) by following the instructions provided in the proxy materials, or you can vote by mailing your proxy as described in the proxy materials. If your shares are held in street name, you will receive instructions from your broker or other nominee that holds your shares explaining how to vote your shares, and you may also have the choice of instructing the record holder as to the voting of your shares over the Internet or by telephone. Proxies submitted by mail must be received before the start of the Annual Meeting.

All properly submitted proxies will be voted in accordance with the instructions contained in those proxies. If no instructions are specified, the proxies will be voted in accordance with the recommendation of our Board of Directors with respect to each of the matters set forth in the accompanying Notice of Meeting. You may revoke your proxy at any time before it is exercised at the meeting by giving our corporate secretary written notice to that effect.

We are an "emerging growth company" under applicable federal securities laws and therefore are permitted to conform with certain reduced public company reporting requirements. As an emerging growth company, we provide in this proxy statement the scaled disclosure permitted under the Jumpstart Our Business Startups Act of 2012, including the compensation disclosures required of a "smaller reporting company," as that term is defined in Rule 12b-2 promulgated under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). In addition, as an emerging growth company, we are not required to conduct votes seeking approval, on an advisory basis, of the compensation of our named executive officers or the frequency with which such votes must be conducted. We will remain an "emerging growth company" until the earliest of (i) the last day of the fiscal year following the fifth anniversary of the date of the first sale of our common stock pursuant to an effective registration statement; (ii) the last day of the fiscal year in which our total annual gross revenue is equal to or more than $1.235 billion; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the Securities and Exchange Commission (the "SEC").

Even after we are no longer an "emerging growth company," we may remain a "smaller reporting company."

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This proxy statement and our 2023 Annual Report to Stockholders are also available for viewing,

printing and downloading at:

https://investors.compasstherapeutics.com/financials-filing/annual-meeting

A copy of our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, as filed with the SEC, except for exhibits, will be furnished without charge to any stockholder upon written request to Compass Therapeutics, Inc., 80 Guest Street, Suite 601, Boston, MA 02135, Attention: Corporate Secretary. This proxy statement and our Annual Report on Form 10-K for the fiscal year ended December 31, 2023 are also available on the SEC's website at www.sec.gov or in the "Annual Meeting" item of the "Investors" section of our website at www.compasstherapeutics.com.

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COMPASS THERAPEUTICS, INC.

PROXY STATEMENT

FOR THE 2024 ANNUAL MEETING OF STOCKHOLDERS

GENERAL INFORMATION

When are this proxy statement and the accompanying materials scheduled to be sent to stockholders?

We have elected to provide access to our proxy materials to our stockholders via the Internet. Accordingly, on or about April 29, 2024, we will begin mailing a Notice of Internet Availability of Proxy Materials (the "Notice"). Our proxy materials, including the Notice of 2024 Annual Meeting of Stockholders, this proxy statement and the accompanying proxy card or, for shares held in street name (i.e. held for your account by a broker or other nominee), a voting instruction form, and the 2023 Annual Report to Stockholders (the "2023 Annual Report") will be mailed or made available to stockholders on the Internet on or about the same date.

Why did I receive a Notice of Internet Availability of Proxy Materials instead of a full set of proxy materials?

Pursuant to rules adopted by the U.S. Securities and Exchange Commission ("SEC"), for most stockholders, we are providing access to our proxy materials over the Internet rather than printing and mailing our proxy materials. We believe following this process will expedite the receipt of such materials and will help lower our costs and reduce the environmental impact of our annual meeting materials. Therefore, the Notice was mailed to holders of record and beneficial owners of our common stock starting on or about April 29, 2024. The Notice provides instructions as to how stockholders may access and review our proxy materials, including the Notice of 2024 Annual Meeting of Stockholders, this proxy statement, the proxy card and our 2023 Annual Report, on the website referred to in the Notice or, alternatively, how to request that a copy of the proxy materials, including a proxy card, be sent to them by mail. The Notice also provides voting instructions. In addition, stockholders of record may request to receive the proxy materials in printed form by mail or electronically by e-mail on an ongoing basis for future stockholder meetings. Please note that while our proxy materials are available at the website referenced in the Notice, and our Notice of 2024 Annual Meeting of Stockholders, this proxy statement and our 2023 Annual Report are available on our website, no other information contained on either website is incorporated by reference in or considered to be a part of this proxy statement.

Who is soliciting my vote?

Our Board of Directors is soliciting your vote for the Annual Meeting.

When is the record date for the Annual Meeting?

The record date for determination of stockholders entitled to vote at the Annual Meeting is the close of business on April 17, 2024.

How many votes can be cast by all stockholders?

There were 137,589,171 shares of our common stock, par value $0.0001 per share, outstanding on April 17, 2024, all of which are entitled to vote with respect to all matters to be acted upon at the Annual Meeting. Each stockholder of record is entitled to one vote for each share of our common stock held by such stockholder. None of our shares of undesignated preferred stock were outstanding as of April 17, 2024.

How do I vote my shares without attending the Annual Meeting?

If you do not wish to vote in person or will not be attending the Annual Meeting, you may vote by proxy. You can vote by proxy over the Internet (www.proxyvote.com) or by telephone (1-800-690-6903) by following the instructions provided in the proxy materials, or you can vote by mailing your proxy as described in the proxy materials. Proxies submitted by mail must be received before the start of the Annual Meeting. If your shares are held in street name, you will receive instructions from your broker or other nominee that holds your shares explaining how to vote your shares, and you may also have the choice of instructing the record holder as to the voting of your shares over the Internet or by telephone.

If you complete and submit your proxy before the Annual Meeting, the persons named as proxies will vote the shares represented by your proxy in accordance with your instructions. If you submit a proxy without giving voting instructions, your shares will be voted in the manner recommended by our Board of Directors on all matters presented in this proxy statement, and as the persons named as proxies may determine in their discretion with respect to any other matters properly presented at the Annual Meeting.

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If any other matters are properly presented for consideration at the Annual Meeting, including, among other things, consideration of a motion to adjourn the Annual Meeting to another time or place (including, without limitation, for the purpose of soliciting additional proxies), the persons named in your proxy and acting thereunder will have discretion to vote on those matters in accordance with their best judgment. We do not currently anticipate that any other matters will be raised at the Annual Meeting.

How can I attend and vote at the Annual Meeting?

All stockholders as of the record date, or their duly appointed proxies, may attend the meeting. To attend and participate in the Annual Meeting, stockholders will need to access the live audio webcast of the meeting. To do so, you will need to visit www.virtualshareholdermeeting.com/CMPX2024 and enter the control number provided on the proxy card to pre-register for the Annual Meeting, and beneficial owners of shares held in street name will need to follow the instructions provided in the voting instructions form by the broker, bank or other nominee that holds their shares.

To be admitted to the Annual Meeting and vote your shares, stockholders must register at www.virtualshareholdermeeting.com/CMPX2024 and provide the control number located in the shaded gray box on the proxy card.

Stockholders who have completed registration will receive an email with further instructions, including a unique link to access the Annual Meeting.

The live audio webcast of the Annual Meeting will begin promptly at 10:00 a.m. Eastern Time. We encourage stockholders to login to this website and access the webcast before the Annual Meeting's start time by following the instructions in the email received on the morning of the Annual Meeting. You should allow ample time in advance of the meeting.

Additionally, questions regarding how to attend and participate via the Internet can be answered by calling the phone number provided in the email received prior to the Annual Meeting.

As part of the Annual Meeting, we will hold a live question and answer session, during which we intend to answer questions submitted during the meeting in accordance with the Annual Meeting's Rules of Conduct that are pertinent to Compass and the meeting matters, as time permits. Questions and answers will be grouped by topic and substantially similar questions will be grouped and answered once.

As part of the Annual Meeting, we will hold a question-and-answer session, during which we intend to answer questions submitted during the meeting in accordance with the Annual Meeting's Rules of Conduct that are pertinent Compass and the meeting matters, as time permits. Questions and answers will be grouped by topic and substantially similar questions will be grouped and answered once. Only stockholders who register and subsequently log in to attend the Annual Meeting will be able to ask questions at the Annual Meeting.

The Annual Meeting's Rules of Conduct will be posted on www.virtualshareholdermeeting.com/CMPX2024 approximately one week prior to the date of the Annual Meeting.

How do I revoke my proxy?

You may revoke your proxy by (1) following the instructions in the proxy materials and entering a new vote by mail that we receive before the start of the Annual Meeting or over the Internet, (2) attending and voting at the Annual Meeting (although attendance at the Annual Meeting will not in and of itself revoke a proxy), or (3) by filing an instrument in writing revoking the proxy or another duly executed proxy bearing a later date with our Corporate Secretary. Any written notice of revocation or subsequent proxy card must be received by our Corporate Secretary prior to the taking of the vote at the Annual Meeting. Such written notice of revocation or subsequent proxy card should be hand delivered to our Corporate Secretary or sent to our principal executive offices at Compass Therapeutics, Inc., 80 Guest Street, Suite 601, Boston, MA 02135, Attention: Corporate Secretary.

If a broker, bank, or other nominee holds your shares, you must contact such broker, bank, or nominee to find out how to change your vote.

How is a quorum reached?

Our Amended and Restated Bylaws provide that a majority of the outstanding shares entitled to vote, present in person or represented by proxy, will constitute a quorum for the transaction of business at the Annual Meeting.

Under the General Corporation Law of the State of Delaware, shares that are voted "abstain" or "withheld" and broker "non-votes" are counted as present for purposes of determining whether a quorum is present at the Annual Meeting. If a quorum is not present, the meeting may be adjourned until a quorum is obtained.

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How is the vote counted?

Under our Amended and Restated Bylaws, any proposal other than an election of directors (which is decided by a plurality of the votes properly cast on the election of directors) is decided by a majority of the votes properly cast for and against such proposal, except where a larger vote is required by law or by our Amended and Restated Certificate of Incorporation or our Amended and Restated Bylaws. Votes withheld, abstentions, and broker "non-votes," as applicable, are not included in the tabulation of the voting results on any proposal and, therefore, do not have an impact on the outcome of the proposals. A broker "non-vote" occurs when a nominee holding shares for a beneficial owner does not vote on a particular proposal because the nominee does not have discretionary voting power with respect to that item and has not received instructions from the beneficial owner.

If your shares are held in "street name" by a brokerage firm, your brokerage firm is required to vote your shares according to your instructions. If you do not give instructions to your brokerage firm, the brokerage firm will still be able to vote your shares with respect to "discretionary" items but will not be allowed to vote your shares with respect to "non-discretionary" items. Proposal No. 1 is a "non-discretionary" item. If you do not instruct your broker how to vote with respect to this proposal, your broker may not vote for this proposal, and your share will be counted as broker "non-votes." Proposal No. 2 is a discretionary item, and your brokerage firm will be able to vote on this proposal even if it does not receive instructions from you.

For Proposal No. 1, to be elected, each of the nominees for class I director must receive a plurality of the votes properly cast on the election of directors, meaning that the two director nominees receiving the highest number of affirmative votes will be elected as directors. You may vote either FOR all the nominees, FOR any one of the nominees, WITHHOLD your vote from all the nominees or WITHHOLD your vote from any one of the nominees. Votes that are withheld and broker non-votes will have no effect on the election of directors.

For Proposal No. 2, the affirmative vote of a majority of the votes properly cast for this proposal is required to ratify the appointment of CohnReznick LLP as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2024. Abstentions and broker non-votes, if any, will have no effect on the outcome of this vote.

Who pays the cost for soliciting proxies?

We are making this solicitation and will pay the entire cost of preparing and distributing the proxy materials and soliciting votes. Our officers and employees may, without compensation other than their regular compensation, solicit proxies through further mailings, personal conversations, facsimile transmissions, e-mails, or otherwise.

How may stockholders submit matters for consideration at an annual meeting?

The required notice must be in writing and received by our corporate secretary at our principal executive offices not less than 90 days nor more than 120 days prior to the first anniversary of the preceding year's annual meeting. However, in the event that the date of the annual meeting is advanced by more than 30 days, or delayed by more than 60 days, from the first anniversary of the preceding year's annual meeting, or if no annual meeting were held in the preceding year, a stockholder's notice must be so received no earlier than the 120th day prior to such annual meeting and not later than the close of business on the later of (A) the 90th day prior to such annual meeting and (B) the tenth day following the day on which notice of the date of such annual meeting was mailed or public disclosure of the date of such annual meeting was made, whichever first occurs.

In addition, any stockholder proposal intended to be included in the proxy statement for the next annual meeting of our stockholders in 2025 must also satisfy the requirements of Rule 14a-8 under the Exchange Act and be received not later than December 30, 2024. If the date of the annual meeting is moved by more than 30 days from the date contemplated at the time of the previous year's proxy statement, then notice must be received within a reasonable time before we begin to print and send proxy materials. If that happens, we will publicly announce the deadline for submitting a proposal in a press release or in a document filed with the SEC.

To comply with the universal proxy rules, stockholders who intend to solicit proxies in support of director nominees other than Compass's nominees must provide notice that sets forth the information required by Rule 14a-19 under the Exchange Act no later than April 14, 2025. Stockholder proposals and the required notice should be addressed to Compass Therapeutics, Inc., 80 Guest Street, Suite 601, Boston, MA 02135, Attention: Corporate Secretary.

How can I know the voting results?

We plan to announce preliminary voting results at the Annual Meeting and will publish final results in a Current Report on Form 8-K to be filed with the SEC within four business days following the Annual Meeting.

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