Aptevo Therapeutics Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No.__)

Check the appropriate box:

Aptevo Therapeutics Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply)

APTEVO THERAPEUTICS INC.

2401 4th Avenue, Suite 1050

Seattle, Washington 98121

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held On August 21, 2026

Dear Aptevo Stockholder:

You are cordially invited to virtually attend the 2026 annual meeting of stockholders (the “Annual Meeting”) of Aptevo Therapeutics Inc., a Delaware corporation (the “Company”). The meeting will be held on August 21, 2026 at 10 a.m. Pacific Time. To facilitate stockholder participation and save costs, the Annual Meeting will be held in a virtual meeting format only at www.virtualshareholdermeeting.com/APVO2026. The meeting will be held for the following purposes:

1. To elect two nominees to serve on the Company’s Board of Directors (the “Board”) to hold office until the 2029 Annual Meeting of Stockholders and until their respective successors are duly elected and qualified (“Proposal 1” or the “Director Election Proposal”).

2. To ratify the selection of Baker Tilly US, LLP as the Company’s independent registered public accounting firm for the year ending December 31, 2026 (“Proposal 2” or the “Auditor Ratification Proposal”).

3. To approve, on a non-binding advisory basis, the compensation paid to the Company’s named executive officers in 2025, as disclosed in the proxy statement (“Proposal 3” or the “Say-on-Pay Proposal”).

4. To approve the Aptevo Therapeutics Inc. Fourth Amended and Restated 2018 Stock Incentive Plan (“Proposal 4” or the “Stock Incentive Plan Proposal”).

5. To conduct any other business properly brought before the Annual Meeting.

These items of business are more fully described in the proxy statement accompanying this Notice (the “Proxy Statement”).

The record date for the Annual Meeting is July 23, 2026. Only stockholders of record at the close of business on that date may vote on the proposals being presented at the Annual Meeting or any adjournment, postponement, rescheduling, or continuation thereof.

Important Notice Regarding the Availability of Proxy Materials for the Stockholders’ Meeting to Be Held Virtually on August 21, 2026 at 10 a.m. Pacific Time at www.virtualshareholdermeeting.com/APVO2026.

The Proxy Statement and Annual Report to stockholders are available at www.proxyvote.com.

By Order of the Board of Directors

/s/ SoYoung Kwon

SVP, General Counsel, Business Development and Corporate Affairs

Seattle, WA

July 31, 2026

You are cordially invited to virtually attend the meeting. Whether or not you expect to virtually attend the meeting, please complete, date, sign and return a proxy card (if you received one), or vote over the telephone or the internet as instructed in these materials, as promptly as possible in order to ensure your representation at the meeting. Even if you have voted by proxy, you may still vote if you virtually attend the meeting.

TABLE OF CONTENTS

APTEVO THERAPEUTICS INC.

2401 4th Avenue, Suite 1050

Seattle, Washington 98121

FOR THE 2026 ANNUAL MEETING OF STOCKHOLDERS

To be held on August 21, 2026

QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

When is this Proxy Statement and accompanying proxy card (“Proxy Card”) first being mailed to stockholders?

This Proxy Statement and Proxy Card are first being mailed on or about July 31, 2026 to stockholders of record of Aptevo Therapeutics Inc. (sometimes referred to as the “Company,” “Aptevo,” “we,” “us” or “our”) entitled to vote on the proposals being presented at the Annual Meeting.

How do I attend the Annual Meeting?

In order to facilitate stockholder participation and save costs, the meeting will be held virtually on August 21, 2026 at 10 a.m. Pacific Time. There will not be a physical meeting. We have worked to offer the same participation opportunities as if you attended the Annual Meeting in person and hope the virtual format will allow more stockholders to participate by removing any barriers caused by travel requirements. You may attend the Annual Meeting virtually, including voting and submitting questions, at www.virtualshareholdermeeting.com/APVO2026 by entering the 16-digit control number included on the Notice of the Annual Meeting of Stockholders (“Notice”) or your proxy card (if you received a printed copy of the proxy materials). You should ensure you have a strong internet connection wherever you intend to participate in the Annual Meeting. We encourage you to access the Annual Meeting before it begins. Virtual check-in will begin at 9:30 a.m. Pacific Time on the date of the Annual Meeting.

Our virtual meeting provider, Broadridge Financial Solutions, Inc. (“Broadridge”), facilitates stockholders’ opportunity to ask questions before and during the meeting. The Annual Meeting site will provide stockholders with information regarding (i) time guidelines for their questions, rules around what types of questions are allowed, and rules for how questions and comments will be recognized and disclosed to meeting participants; and (ii) procedures for posting appropriate questions received during the meeting and our answers on our website as soon as is practical after the meeting. Once you are logged into the Annual Meeting, you will be able to submit your questions directly to the Company. Our virtual meeting will be governed by our rules of conduct and procedures will be posted at www.virtualshareholdermeeting.com/APVO2026 in advance of the Annual Meeting.

You may obtain instructions for how to access the Annual Meeting virtually at www.virtualshareholdermeeting.com/APVO2026. If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time or need support in addressing technical and logistical issues related to accessing the virtual meeting platform, a technical assistance phone number will be made available on the virtual meeting registration page at www.virtualshareholdermeeting.com/APVO2026, 30 minutes prior to the start of the meeting.

Who can vote at the Annual Meeting?

Only stockholders of record at the close of business on July 23, 2026 (the “Record Date”) will be entitled to vote on the proposals being presented at the Annual Meeting. On the Record Date, there were 1,517,945 shares of common stock of the Company (“Common Stock”) outstanding and entitled to vote at the Annual Meeting. Our Common Stock is our only class of voting stock.

If on July 23, 2026 your shares were registered directly in your name with the Company’s transfer agent, Broadridge Financial Solutions, Inc., then you are a stockholder of record. As a stockholder of record, you may vote by virtually attending the Annual Meeting and voting during the Annual Meeting or vote over the telephone or the internet or by proxy card. Whether or not you plan to virtually attend the Annual Meeting, we urge you to vote by proxy to ensure your vote is counted.

Beneficial Owner: Shares Registered in the Name of a Broker or Other Nominee

If on July 23, 2026 your shares were held, not in your name, but rather in an account at a brokerage firm, bank, dealer, other similar organization, or other nominee, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting on the proposals being presented at the Annual Meeting. As a beneficial owner, you have the right to direct your broker or other agent regarding how to vote the shares in your account. You are also invited to virtually attend the Annual Meeting. However, since you are not the stockholder of record, you may not vote your shares at the Annual Meeting unless you request and obtain a valid proxy from your broker or other agent.

What am I voting on?

There are four matters scheduled for a vote:

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Proposal 1: To elect two director nominees to serve on the Board to hold office until the 2029 Annual Meeting of Stockholders and until their respective successors are duly elected and qualified;

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Proposal 2: To ratify the selection of Baker Tilly US, LLP as the Company’s independent registered public accounting firm for the year ending December 31, 2026;

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Proposal 3: To approve, on a non-binding advisory basis, the compensation paid to the Company’s named executive officers in 2025, as disclosed in the Proxy Statement; and

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Proposal 4: To approve the Aptevo Therapeutics Inc. Fourth Amended and Restated 2018 Stock Incentive Plan.

What if another matter is properly brought before the meeting?

The Board knows of no other matters that will be presented for consideration at the Annual Meeting. If any other matters are properly brought before the meeting, it is the intention of the persons named in the accompanying proxy card to vote on those matters in accordance with their best judgment, subject to compliance with Rule 14a-4(c) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

How do I vote?

For the Director Election Proposal, you may either vote “For” each of the nominees to the Board or you may “Withhold” your vote for any nominee you specify. For the Auditor Ratification Proposal, you may vote “For” or “Against” or abstain from voting. For the Say-on-Pay Proposal, you may vote “For” or “Against” or abstain from voting. For the Stock Incentive Plan Proposal, you may vote “For” or “Against” or abstain from voting.

The Board recommends that you vote:

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“For” the election of each of the director nominees named in the Director Election Proposal;

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“For” the Auditor Ratification Proposal;

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“FOR” the Say-on-Pay Proposal; and

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“FOR” the Stock Incentive Plan Proposal.

The procedures for voting are as follows:

If you are a stockholder of record, you may vote by virtually attending the Annual Meeting and voting during the Annual Meeting, vote by proxy over the telephone, vote by proxy through the Internet or vote by proxy using a proxy card that you may request or that we may elect to deliver at a later time. Whether or not you plan to virtually attend the Annual Meeting, we urge you to vote by proxy to ensure your vote is counted. You may still virtually attend the Annual Meeting and vote during the Annual Meeting even if you have already voted by proxy.

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To vote using the proxy card (if one was provided), simply complete, sign and date the proxy card and return it promptly in the envelope provided. If you return your signed proxy card to us before the Annual Meeting, we will vote your shares as you direct.

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To vote over the telephone, dial toll-free 1-800-690-6903 using a touch-tone phone and follow the recorded instructions. You will be asked to provide the company number and control number included on your Notice. Your telephone vote must be received by 11:59 p.m. EDT on August 20, 2026 to be counted.

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To vote through the Internet, go to www.proxyvote.com to complete an electronic proxy card. You will be asked to provide the company number and control number from your Proxy Card. Your internet vote must be received by 11:59 p.m. EDT on August 20, 2026 to be counted.

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If you virtually attend the Annual Meeting, you can also vote during the Annual Meeting by visiting www.virtualshareholdermeeting.com/APVO2026 and entering the 16-digit control number included on your Proxy Card (if you received a printed copy of the proxy materials).

Beneficial Owner: Shares Registered in the Name of Broker or Bank

If you are a beneficial owner of shares registered in the name of your broker, bank, or other nominee, you should have received voting instructions from that organization rather than from us. Simply follow the instructions in the voting instruction form to ensure that your vote is counted. To vote virtually at the Annual Meeting, you must obtain a valid proxy from your broker, bank or other agent. Follow the instructions from your broker, bank or other agent included with these proxy materials, or contact your broker, bank or other agent to request a proxy form well in advance of the meeting.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you own as of July 23, 2026.

What happens if I do not vote?

If you are a stockholder of record and do not vote by completing your proxy card, or by telephone, through the internet, or by virtually attending the Annual Meeting and voting during the Annual Meeting, your shares will not be voted.

Beneficial Owner: Shares Registered in the Name of Broker or Other Nominee

If you are a beneficial owner and do not instruct your broker, bank, or other agent how to vote your shares, the question of whether your broker or nominee will still be able to vote your shares depends on whether the particular proposal is a “routine” matter. Under the rules of the New York Stock Exchange (“NYSE”), which are also applicable to Nasdaq-listed companies, brokers, banks and other securities intermediaries that are subject to NYSE rules may use their discretion to vote your “uninstructed” shares on matters considered to be “routine” under NYSE rules but not with respect to “non-routine” matters. The Auditor Ratification Proposal is considered to be “routine” under NYSE rules such that your broker, bank or other agent may vote your shares on such proposal in the absence of your voting instructions. The Director Election Proposal, the Say-on-Pay Proposal and the Stock Incentive Plan Proposal are considered “non-routine” such that your broker, bank or other agent may not vote your shares on such proposals in the absence of your voting instructions.

What if I return a Proxy Card or otherwise vote but do not make specific choices?

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, as applicable:

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“For” the election of each of the director nominees named in the Director Election Proposal;

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“For” the Auditor Ratification Proposal;

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“FOR” the Say-on-Pay Proposal; and

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“FOR” the Stock Incentive Plan Proposal.

If any other matter is properly presented at the Annual Meeting and any adjournments or postponements thereof, your proxyholder (one of the individuals named on the enclosed proxy card) will vote your shares using his or her best judgment.

Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. We have engaged Okapi Partners LLC (“Okapi”) to assist in the solicitation of proxies for the Annual Meeting. We have agreed to pay Okapi a fee of $15,000. We will also reimburse Okapi for reasonable out-of-pocket expenses and will indemnify Okapi and its affiliates against certain claims, liabilities, losses, damages and expenses. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by telephone or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners. The entire cost of soliciting proxies on behalf of the Board will be borne by the Company.

What does it mean if I receive more than one Proxy Statement or Proxy Card?

If you receive more than one Proxy Statement or Proxy Card, your shares may be registered in more than one name or in different brokerage accounts. Please follow the voting instructions on the Proxy Cards to ensure that all of your shares are voted. Remember, you may vote by telephone, Internet or by signing, dating and returning a Proxy Card, or by voting at the Annual Meeting.

Can I change my vote or revoke my proxy?

Yes. You may change your vote or revoke your proxy at any time before the final vote at the Annual Meeting. If you are the record holder of your shares, you may change your vote or revoke your proxy in any one of the following ways:

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You may submit a properly completed Proxy Card with a later date.

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You may grant a subsequent proxy by telephone or through the internet.

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You may send a timely written notice that you are revoking your proxy to Aptevo’s Corporate Secretary at 2401 4th Avenue, Suite 1050, Seattle, Washington 98121.

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You may virtually attend the Annual Meeting and vote virtually during the Annual Meeting. Simply virtually attending the Annual Meeting will not, by itself, revoke your proxy.

Beneficial Owner: Shares Registered in the Name of Broker or Bank

If your shares are held by your broker or bank as a nominee or agent, you should follow the instructions provided by your broker or bank.

When are stockholder proposals and director nominations due for next year’s annual meeting?

Pursuant to Rule 14a-8 of the Exchange Act, to be considered for inclusion in next year’s proxy materials, your proposal must be submitted in writing by April 2, 2027, to Aptevo’s Corporate Secretary at 2401 4th Avenue, Suite 1050, Seattle, Washington 98121. We also encourage you to submit any such proposals via email to the Corporate Secretary at LegalAffairs@apvo.com. Such a proposal must satisfy the rules and regulations of the Securities and Exchange Commission (the “SEC”). In order to avoid controversy, stockholders should submit proposals by means (including electronic) that permit them to prove the date of delivery. To comply with the universal proxy rules, stockholders who intend to solicit proxies in support of director nominees other than the Company’s nominees must provide notice that sets forth the information required by Rule 14a-19 under the Securities Exchange Act of 1934 no later than June 22, 2027.

In addition, our Amended and Restated Bylaws require that we be given advance written notice for nominations for election to our Board and of other business that stockholders wish to present for consideration at an annual meeting of stockholders (other than those proposals of business intended to be included in our proxy statement in accordance with Rule 14a-8 under the Exchange Act). The Amended and Restated Bylaws require that a stockholder who intends to present a proposal at an annual meeting of stockholders submit the proposal to the Corporate Secretary not less than 90 and no more than 120 days before the first anniversary of the date of the previous year’s annual meeting. Therefore, to be eligible for consideration at the 2027 Annual Meeting of Stockholders, such a proposal and any nominations for director must be received by the Corporate Secretary between April 23, 2027 and May 23, 2027; provided, however, that in the event that the date of the annual meeting is advanced by more than 20 days, or delayed by more than 60 days, from the first anniversary of the preceding year’s annual meeting, a stockholder’s notice must be so received not 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. This advance notice period is intended to allow stockholders an opportunity to consider all business and nominees expected to be considered at the meeting. Any proposals received after the applicable deadline may be considered untimely and may be excluded.

If a stockholder who wishes to present a proposal before the 2027 Annual Meeting outside of Rule 14a-8 of the Exchange Act fails to notify us by the required date, the proxies that our Board solicits for the 2027 Annual Meeting will confer discretionary authority on the person named in the proxy to vote on the stockholder’s proposal if it is properly brought before that meeting subject to compliance with Rule 14a-4(c) of the Exchange Act. If a stockholder makes timely notification, the proxies may still confer discretionary authority to the person named in the proxy under circumstances consistent with the SEC proxy rules, including Rule 14a-4(c) of the Exchange Act.

What are “broker non-votes”?

If you are a beneficial owner whose shares of record are held by a broker, you may instruct your broker how to vote your shares. If you do not give instructions to your broker, the broker will determine if it has the discretionary authority to vote on the particular matter. Under NYSE rules, which are also applicable to Nasdaq-listed companies, brokers, banks and other securities intermediaries that are subject to NYSE rules may use their discretion to vote your “uninstructed” shares on matters considered to be “routine” under NYSE rules but not with respect to “non-routine” matters.

A broker non-vote occurs when a broker, bank or other agent has not received voting instructions from the beneficial owner of the shares and the broker, bank or other agent cannot vote the shares because the matter is considered “non-routine” under NYSE rules. Broker non-votes, if any, will be counted for purposes of calculating whether a quorum is present at the meeting, but will not be counted for purposes of determining the number of votes cast with respect to a particular proposal.

The Auditor Ratification Proposal is a “routine” matter, and banks and brokerage firms may vote your shares on such proposal if you have not given voting instructions. The Director Election Proposal, the Say-on-Pay Proposal, and the Stock Incentive Plan Proposal are considered “non-routine,” and banks and brokerage firms may not vote your shares on such proposals in the absence of your voting instructions.

How many votes are needed to approve each proposal?

Directors are elected by a plurality of the votes of the holders of shares present at the Annual Meeting or represented by proxy and entitled to vote on the election of directors. Accordingly, for the Director Election Proposal, the two nominees receiving the highest number of affirmative votes will be elected. Votes withheld and broker non-votes, if any, will have no effect on the results of the Director Election Proposal.

To be approved, the Auditor Ratification Proposal, the Say-on-Pay Proposal and the Stock Incentive Plan Proposal require the affirmative vote of a majority of the votes cast by the holders of all of the shares of Common Stock present virtually or represented by proxy at the Annual Meeting. Abstentions and broker non-votes, if any, will have no effect on the results of these votes.

Each of the proposals is separate and apart from each other with votes of each proposal separately counted.

What is the quorum requirement and how will votes be counted?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least one-third of the Common Stock issued and outstanding and entitled to vote are present virtually at the Annual Meeting or represented by proxy. On the record date for the Annual Meeting, there were 1,517,945 shares of Common Stock outstanding and entitled to vote. Thus, the holders of 505,981 shares of Common Stock must be present virtually or represented by proxy at the Annual Meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or if you vote by virtually attending the Annual Meeting and voting during the Annual Meeting. Withheld votes, abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the chairman of the meeting or the holders of a majority of shares present at the Annual Meeting or represented by proxy and entitled to vote may adjourn or postpone the Annual Meeting to another date.

An inspector of elections appointed for the meeting will determine whether a quorum is present and will tabulate votes cast by proxy or at the meeting. If a quorum is not present, we expect to adjourn or postpone the Annual Meeting until we obtain a quorum.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results will be announced at the Annual Meeting. In addition, final voting results will be published in a Current Report on Form 8-K that we expect to file within four business days after the Annual Meeting. If final voting results are not available to us in time to file a Current Report on Form 8-K within four business days after the Annual Meeting, we intend to file a Current Report on Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Current Report on Form 8-K to publish the final results.

What proxy materials are available on the internet?

The Proxy Statement and the Annual Report on Form 10-K for the fiscal year ended December 31, 2025 are available at www.proxyvote.com.

Proposal 1