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 SPECIAL MEETING OF STOCKHOLDERS

To Be Held On May 1, 2025

Dear Aptevo Stockholder:

You are cordially invited to virtually attend a special meeting of the stockholders (the “Special Meeting”) of Aptevo Therapeutics Inc., a Delaware corporation (“Aptevo,” “we,” “us,” “our,” or the “Company”). The meeting will be held on May 1, 2025 at 10 a.m. Pacific Time. To facilitate stockholder participation and save costs, the Special Meeting will be held in a virtual meeting format only at www.virtualshareholdermeeting.com/APVO2025SM. The meeting will be held for the following purposes:

1. To approve, in accordance with Nasdaq Listing Rule 5635(d), the issuance of more than 19.99% of our outstanding Common Stock, par value $0.001 per share (“Common Stock”), including (i) Common Stock issuable upon the exercise of the common warrants (the “Common Warrants”), issued and sold in a private placement pursuant to that certain Securities Purchase Agreement, dated as of April 3, 2025, by and among the Company and purchasers thereto (the “Purchase Agreement”) and (ii) Common Stock issuable upon the exercise of those certain existing common warrants that were previously issued on December 12, 2024, to purchase 1,647,088 shares of Common Stock, and have an exercise price of $9.53 per share, that were amended in connection with the issuance of the Common Warrants (the "Amended Warrants") (“Proposal 1” or the “Stock Issuance and Warrant Proposal”);

2. To approve an amendment to our Amended and Restated Certificate of Incorporation, as amended (“Certificate of Incorporation”), to effect a reverse stock split of our Common Stock, at a ratio in the range of 1-for-6 to 1-for-20, with such ratio to be determined in the discretion of our board of directors and with such reverse stock split to be effected at such time and date, if at all, as determined by our board of directors in its sole discretion (“Proposal 2” or the “Reverse Stock Split Proposal”); and

3. To authorize an adjournment of the meeting to a later date or dates, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes in favor of Proposal 1 or Proposal 2 (“Proposal 3” or the “Adjournment Proposal”).

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

In addition to the foregoing, the Special Meeting will include the transaction of any other business relating to the purpose or purposes stated in this Notice and the accompanying Proxy Statement that may be properly brought before the meeting or any continuation, adjournment or postponement thereof.

The record date for the Special Meeting is April 4, 2025. Only stockholders of record at the close of business on that date may vote on the proposals being presented at the Special Meeting or any adjournment, postponement, rescheduling, or continuation thereof.

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting to Be Held Virtually on May 1, 2025 at 10 a.m. Pacific Time at www.virtualshareholdermeeting.com/APVO2025SM.

The Proxy Statement is 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

April , 2025

Whether or not you expect to attend the virtual meeting, please complete, date, sign and return the enclosed proxy, 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 attend the virtual meeting. Please note, however, that if your shares are held of record by a broker, bank or other nominee and you wish to vote at the virtual meeting, you must obtain a proxy issued in your name from that record holder.

TABLE OF CONTENTS

APTEVO THERAPEUTICS INC.

2401 4th Avenue, Suite 1050

Seattle, Washington 98121

PROXY STATEMENT

FOR THE SPECIAL MEETING OF STOCKHOLDERS

To be held on May 1, 2025

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 April 21, 2025 to stockholders of record entitled to vote at the Special Meeting.

How do I attend the Special Meeting?

In order to facilitate stockholder participation and save costs, the meeting will be held virtually on May 1, 2025 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 Special Meeting in person and hope the online format will allow more stockholders to participate by removing any barriers caused by travel requirements. You may attend the Special Meeting online, including voting and submitting questions, at www.virtualshareholdermeeting.com/APVO2025SM in advance of the Special Meeting by entering the 16-digit control number included on your Proxy Card. You should ensure you have a strong Internet connection wherever you intend to participate in the Special Meeting. We encourage you to access the Special Meeting before it begins. Online check-in will begin at 9:30 a.m. Pacific Time on the date of the Special Meeting.

Our virtual meeting provider, Broadridge, facilitates stockholders’ opportunity to ask questions before and during the meeting. The Special 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 practical after the meeting. Once you are logged into the Special 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, which will be posted at www.virtualshareholdermeeting.com/APVO2025SM in advance of the Special Meeting.

You may obtain instructions for how to access the Special Meeting online at www.virtualshareholdermeeting.com/APVO2025SM. 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/APVO2025SM, 30 minutes prior to the start of the meeting.

Who can vote at the Special Meeting?

Only stockholders of record at the close of business on April 4, 2025 (the “Record Date”) will be entitled to vote on the proposals being presented at the Special Meeting. On the Record Date, there were 3,223,214 shares of Common Stock outstanding and entitled to vote at the Special Meeting. Our Common Stock is our only class of voting stock.

Stockholder of Record: Shares Registered in Your Name

If on April 4, 2025, your shares were registered directly in your name with the Company’s transfer agent, Broadridge Corporate Issuer Solutions, Inc., then you are a stockholder of record. As a stockholder of record, you may vote by virtually attending the Special Meeting and voting during the Special Meeting or vote over the telephone or the Internet

or by proxy card. Whether or not you plan to virtually attend the Special 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 April 4, 2025, 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 Special 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 Special Meeting. However, since you are not the stockholder of record, you may not vote your shares at the Special Meeting unless you request and obtain a valid proxy from your broker or other agent.

What am I voting on?

There are three matters scheduled for a vote:

How does the Board of Directors of the Company (the “Board”) recommend that I vote on the proposals?

The Board recommends that you vote as follows:

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 Special 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?

All shares represented by valid proxies that we receive through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the Proxy Card or as instructed via the Internet or telephone. You may specify whether your shares should be voted for, against, or abstain with respect to each of the proposals. Voting by proxy will not affect your right to attend the Special Meeting.

The procedures for voting are as follows:

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record, you may vote by virtually attending the Special Meeting and voting during the Special Meeting, vote by proxy over the telephone, vote by proxy through the Internet or vote by proxy using a Proxy Card. Whether or not you plan to virtually attend the Special Meeting, we urge you to vote by proxy to ensure your vote is counted. You may still virtually attend the Special Meeting and vote during the Special Meeting even if you have already voted by proxy.

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 online at the Special 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 April 4, 2025.

What happens if I do not vote?

Stockholder of Record: Shares Registered in Your Name

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 Special Meeting and voting during the Special 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. Due to the timing of this proxy mailing, which is less than 15 days before the Special Meeting, your broker, bank, or other agent will also lack discretionary authority to vote on routine matters without your instructions. Therefore, it is important that you provide your voting instructions to your broker, bank, or other agent to ensure your vote is counted for the Stock Issuance and Warrant Proposal, the Reverse Stock Split Proposal and the Adjournment Proposal.

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

If you voted by proxy without marking any voting selections, then the proxy holders will vote your shares as recommended by the Board on all matters presented in this Proxy Statement, and as the proxy holders may determine in their discretion with respect to any other matters properly presented for a vote at the Special Meeting.

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 Special 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 and Proxy Card?

If you receive more than one Proxy Statement and 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 Special Meeting.

Can I change my vote or revoke my proxy?

Stockholder of Record: Shares Registered in Your Name

Yes. You may change your vote or revoke your proxy at any time before the final vote at the Special 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:

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.

Your most current vote that is valid, whether by telephone, Internet or proxy card is the one that will be counted.

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. Due to the timing of this proxy mailing, which is less than 15 days before the Special Meeting, brokers will also lack discretionary authority to vote on routine matters without your instructions. Therefore, it is important that you provide your voting instructions to your broker to ensure your vote is counted.

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. 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 Reverse Stock Split Proposal and the Adjournment Proposal are “routine” matters. However, banks and brokerage firms may not vote your shares on such proposals if you have not given voting instructions due to the timing of this proxy mailing. The Stock Issuance and Warrant Proposal is considered “non-routine,” and banks and brokerage firms may not vote your shares on such proposal in the absence of your voting instructions.

How many votes are needed to approve the proposals?

To be approved, the Stock Issuance and Warrant Proposal, the Reverse Stock Split Proposal and the Adjournment 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 Special Meeting, provided that shares of Common Stock issued in connection with the registered direct offering that closed on April 4, 2025, will be excluded for purposes of counting the votes cast on the Stock Issuance and Warrant Proposal but will be counted as votes cast for the Reverse Stock Split Proposal and the Adjournment Proposal and will be included for purposes of the quorum requirement. Abstentions and broker non-votes, if any, will have no effect on the results of these votes.

These proposals are 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 for the Special Meeting if stockholders holding at least one-third of the Common Stock issued and outstanding and entitled to vote are present virtually at the Special Meeting or represented by proxy. On the record date for the Special Meeting, there were 3,223,214 shares outstanding and entitled to vote at the Special Meeting. Thus, the holders of 1,074,405 shares must be present virtually or represented by proxy at the Special Meeting to have a quorum.

Abstentions and broker non-votes, if any, will be counted towards the quorum requirement. If there is no quorum, the chairman of the meeting or stockholders present virtually at the Special Meeting or represented by proxy and entitled to vote may adjourn or postpone the Special 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 Special Meeting until we obtain a quorum.

What will happen if stockholders fail to approve the Stock Issuance and Warrant Proposal at the Special Meeting?

If stockholders fail to approve the Stock Issuance and Warrant Proposal at the Special Meeting, the Common Warrants and Amended Warrants will not be exercisable. If these consequences occur, we may have difficulty finding alternative sources of capital to fund the continued clinical development of our product candidates, working capital, and other general corporate purposes in the future on terms favorable to us or at all. In addition, pursuant to the Purchase Agreement, we will be required to call a meeting every sixty (60) days to seek stockholder approval until stockholder approval is obtained or the Common Warrants are no longer outstanding.

See “Effect of the Proposal” under Proposal 1 below for additional discussion of the effect on our existing common stockholders of the Stock Issuance and Warrant Proposal.

What will happen if stockholders fail to approve the Reverse Stock Split Proposal at the Special Meeting?

Our Common Stock is currently listed on Nasdaq. Nasdaq has minimum requirements that a company must meet in order to remain listed on Nasdaq, including corporate governance standards and a requirement that we maintain a minimum closing bid price of $1.00 per share, among other requirements.

On June 25, 2024, we received a letter from Nasdaq notifying us that, for the last 30 consecutive business days, the bid price of our Common Stock had closed below $1.00 per share, the minimum closing bid price required by the continued listing requirements of Nasdaq Listing Rule 5550(a)(2) (the “Bid Price Requirement”). On December 3, 2024, we filed a Certificate of Amendment to our Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a 1-for-37 reverse stock split of our outstanding Common Stock (the “December 2024 Reverse Stock Split”). The December 2024 Reverse Stock Split became effective on December 3, 2024 at 5:01 p.m. Eastern Time, and our Common Stock began trading on The Nasdaq Capital Market LLC (“The Nasdaq Capital Market”), on a split-adjusted basis, at market open on December 4, 2024. On December 18, 2024, we received notification from Nasdaq that for ten consecutive business days, the closing bid price of our Common Stock was at least $1.00 per share, and accordingly, we regained compliance with the Bid Price Requirement, and that the matter is now closed.

Pursuant to Nasdaq Listing Rule 5810(c)(3)(A)(iv), we will not be eligible for any compliance period specified in Nasdaq Listing Rule 5810(c)(3)(A) if we have effected a reverse stock split over the prior one-year period or have effected one or more reverse stock splits over the prior two-year period with a cumulative ratio of 250 shares or more to one. The December 2024 Reverse Stock Split, when combined with the 1-for-44 reverse stock split previously effectuated on March 5, 2024, have effectuated a cumulative reverse stock split with a cumulative ratio of 250 shares or more to one. As a result, if we fail to meet the Bid Price Requirement within the two-year period after March 5, 2024, we would be subject to delisting by Nasdaq without any opportunity for a cure period.

In the future, if we fail to maintain the Bid Price Requirement and a final determination is made by Nasdaq that our Common Stock must be delisted, the liquidity of our Common Stock would be adversely affected and the market price of our Common Stock could decrease. In addition, if delisted, we would no longer be subject to Nasdaq rules, including rules requiring us to have a certain number of independent directors and to meet other corporate governance standards. Our failure to be listed on Nasdaq or another established securities market would have a material adverse effect on the value of your investment in us.

If stockholders fail to approve the Reverse Stock Split Proposal at the Special Meeting, we may be subject to being delisted without the benefit of any compliance period. In that event, the liquidity of our Common Stock would be adversely affected, and the market price of our Common Stock could decrease.

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

Preliminary voting results will be announced at the Special 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 Special 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 Special 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 Proxy Card are available at www.proxyvote.com.

Proposal 1

APPROVAL OF THE STOCK ISSUANCE AND WARRANT PROPOSAL

General

In this proposal, we are asking stockholders to approve the issuance of more than 19.99% of our outstanding Common Stock, including (i) Common Stock issuable upon the exercise of the Common Warrants issued and sold in the Private Placement pursuant to the Purchase Agreement and (ii) Common Stock issuable upon the exercise of the Amended Warrants, for purposes of compliance with Nasdaq Listing Rule 5635(d).

Description of the Registered Offering and the Private Placement (the "Offering")

On April 4, 2025, we issued and sold 1,764,710 shares (the “Shares”) of our Common Stock to certain institutional investors in a registered direct offering. In the concurrent Private Placement, we also issued to such investors Common Warrants to purchase up to 3,529,420 shares of our Common Stock. Each share of Common Stock was being offered together with two Common Warrants, each to purchase one share of Common Stock. The combined purchase price was $1.19 per share and accompanying Common Warrants. The Common Warrants have an initial exercise price of $1.19 per share. The Common Warrants and the shares of our Common Stock issuable upon the exercise of the Common Warrants were offered pursuant to an exemption provided in Section 4(a)(2) under the Securities Act of 1933, as amended (the "Securities Act"), and/or Regulation D promulgated thereunder.

In connection with the issuance of the Common Warrants, we have agreed to amend certain existing warrants that were previously issued on December 12, 2024, to purchase 1,647,088 shares of Common Stock and have an exercise price of $9.53 per share (the "Existing Warrants"), such that the Existing Warrants will have a reduced exercise price equal to $1.19 per share and include the same voluntary exercise price adjustments as the Common Warrants.

The Shares, the Common Warrants and the Amended Warrants were separately issued. The Common Warrants and the Amended Warrants will not be exercisable prior to our stockholders approving the terms of the Common Warrants and the Amended Warrants at a meeting of stockholders (the "Stockholder Approval"), subject to certain limitations described therein. The Common Warrants and the Amended Warrants will expire five years from the date of Stockholder Approval. In the event that we are unable to obtain the required Stockholder Approval, the Common Warrants and the Amended Warrants will not be exercisable and therefore have no value.

Material Terms of the Common Warrants

Subject to limited exceptions, a holder of Common Warrants will not have the right to exercise any portion of its warrants if the holder, together with its affiliates, would beneficially own in excess of 4.99% or 9.99% (at the election of the holder) of the number of shares of our Common Stock outstanding immediately after giving effect to such exercise.

In the event of a Fundamental Transaction (as defined in the Common Warrant) and generally including any reorganization, recapitalization or reclassification of our Common Stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding Common Stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding Common Stock, the holders of the Common Warrants will be entitled to receive upon exercise of the Common Warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the Common Warrants immediately prior to such Fundamental Transaction, other than one in which a successor entity that is a publicly traded corporation (whose stock is quoted or listed for trading on a national securities exchange, including, but not limited to, the New York Stock Exchange, the NYSE American, the Nasdaq Global Select Market, the Nasdaq Global Market or the Nasdaq Capital Market) assumes the Common Warrants such that the Common Warrants will be exercisable for the publicly traded common stock of such successor entity. Additionally, as more fully described in the Common Warrants, at the option of the holders of the Common Warrants, the holders can receive consideration in the same type and form of an amount equal to the

Black Scholes value (as defined in the Common Warrant) of such unexercised Common Warrants on the date of consummation of such transaction. In addition, the Common Warrant includes voluntary exercise price adjustment provisions such that we may, at any time during the term of the Common Warrant, reduce the then current exercise price to any amount and for any period of time deemed appropriate by our board of directors, subject to the rules and regulations of the trading market.

We have agreed that pursuant to the Purchase Agreement, from the date of issuance of the Common Warrants to the (3) month anniversary of the closing date of the Private Placement, upon any issuance by us or any of our subsidiaries of Common Stock or Common Stock equivalents for cash consideration, indebtedness or a combination of units thereof (a “Subsequent Financing”), each purchaser will have the right to participate in up to an amount of the Subsequent Financing equal to 50% of the Subsequent Financing on the same terms, conditions and price provided for in the Subsequent Financing.

The Common Warrants were issued and sold without registration under the Securities Act, or state securities laws, in reliance on the exemptions provided by Section 4(a)(2) of the Act and Regulation D promulgated thereunder and in reliance on similar exemptions under applicable state laws. Accordingly, the investor may exercise those Common Warrants and sell the underlying shares only pursuant to an effective registration statement under the Securities Act covering the resale of those shares, an exemption under Rule 144 under the Securities Act, or another applicable exemption under the Securities Act. We have agreed to file a registration statement with the Securities and Exchange Commission (the “SEC”) registering the resale of the shares of Common Stock underlying the Common Warrants as soon as practicable (and in any event within 30 calendar days of the date of the Purchase Agreement).

The Common Warrants will not be exercisable without Stockholder Approval. We have agreed to hold a special meeting of the stockholders, within sixty (60) days following the closing of the Private Placement, in order to seek such Stockholder Approval to permit the exercise of the Common Warrants. In the event that we are unable to obtain the Stockholder Approval, the Common Warrants will not be exercisable and therefore have no value. We have agreed to use reasonable best efforts to hold a special meeting of stockholders in order to obtain Stockholder Approval. If we do not obtain Stockholder Approval with respect to the terms of the Common Warrants at the first special meeting of the stockholders, we have agreed to call a meeting every sixty (60) days thereafter to seek such Stockholder Approval until the date on which Stockholder Approval is obtained or the Common Warrants are no longer outstanding.

Agreements in connection with the Offering

The Purchase Agreement contains customary representations and warranties and agreements of the Company and the purchasers and customary indemnification rights and obligations of the parties. We have agreed not to issue, enter into any agreement to issue or announce the issuance or proposed issuance of, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for shares of common stock or file any registration statement or prospectus, or any amendment or supplement thereto for a period of fifteen (15) days following the closing of the Private Placement, subject to certain exceptions.

In connection with the Offering, we entered into a Placement Agency Agreement (the “Placement Agency Agreement”) on April 3, 2025 with Roth Capital Partners, LLC (the “Placement Agent”), as the exclusive placement agent in connection with the Offering. As compensation to the Placement Agent, we paid the Placement Agent a cash fee of 7.0% of the aggregate gross proceeds raised in the Offering, and reimbursement of certain expenses.

We received net proceeds of approximately $1.9 million from the Offering, excluding the proceeds, if any, from the cash exercise of the Common Warrants issued in the Private Placement and after deducting the estimated offering expenses payable by the Company, including the Placement Agent fees. We intend to use the net proceeds from the Offering for the continued clinical development of our product candidates and for working capital, and other general corporate purposes.

For further information regarding these agreements and the Offering, please refer to our Current Report on Form 8-K filed with the SEC on April 4, 2025. The discussion herein relating to the Purchase Agreement, the Placement Agency Agreement, the Common Warrant, and the Amended Warrant is qualified in its entirety by reference to the transaction documents filed as exhibits to such Form 8-K.

Stockholder Approval

A vote in favor of the Stock Issuance and Warrant Proposal is a vote “FOR” approval of the issuance of the shares of our Common Stock, including Common Stock issuable upon exercise of the Common Warrants and the Amended Warrants. The aggregate number of shares of our Common Stock issuable upon such warrants may exceed 19.99% of the outstanding shares of our Common Stock (determined as of the date of, and without regard for, shares of Common Stock underlying the Common Warrants and the Amended Warrants).

Nasdaq Listing Rule 5635(d) requires stockholder approval in connection with a transaction other than a public offering involving the sale, issuance, or potential issuance by the issuer of common stock (or securities convertible into or exercisable for common stock) equal to 20% or more of the common stock or 20% or more of the voting power outstanding before the issuance for a price that is less than the lower of (i) the company’s Nasdaq Official Closing Price (as reflected on Nasdaq.com) immediately preceding the signing of the binding agreement, or (ii) the average of the company’s Nasdaq Official Closing Price (as reflected on Nasdaq.com) for the five trading days immediately preceding the signing of the binding agreement (the "Minimum Price"). Pursuant to Nasdaq rules, the presence of any provision that could cause the conversion or exercise price of a convertible security to be reduced to below the Minimum Price immediately before the entering into of the binding agreement will cause the transaction to be viewed as a discounted issuance. If an issuance includes common stock and other securities sold together as an investment unit, Nasdaq will attribute a value to securities issued with common stock. If an offering includes the issuance of warrants, then in determining the discount to the Minimum Price, Nasdaq will attribute a value of $0.125 to each “plain vanilla” warrant with an exercise price no less than the offering price of the common stock.

Because the 3,529,420 shares of Common Stock issuable upon exercise of the Common Warrants total more than 19.99% of outstanding shares of Common Stock and the offering price of the Common Stock (excluding the offering price of the Common Warrants) in the Offering is a discounted issuance such that the offering price could drop below the Minimum Price upon adjustment, and the Offering may not be considered a public offering for purposes of the Nasdaq shareholder approval rules, we are asking stockholders to approve the Stock Issuance and Warrant Proposal in respect of the issuance of such shares of Common Stock and related transactions pursuant to Nasdaq Listing Rule 5635(d).

Effect of the Proposal

If stockholders do not approve this Stock Issuance and Warrant Proposal, then the Common Warrants and Amended Warrants will not be exercisable and therefore would have no value, and we would be required to call a meeting every sixty (60) days as described in the Common Warrant to seek stockholder approval until the earlier of the date on which stockholder approval is obtained or the Common Warrants are no longer outstanding. Failure to obtain such approval may discourage future investors from engaging in future financings with us. If these consequences occur, we may have difficulty finding alternative sources of capital to fund our operations in the future on terms favorable to us or at all. We can provide no assurance that we would be successful in raising funds pursuant to additional equity or debt financings or that such funds could be raised at prices that would not create substantial dilution for our existing stockholders. If stockholders approve this Stock Issuance and Warrant Proposal, the Common Warrants and Amended Warrants will be exercisable immediately following such approval.

Certain Risks Associated with the Proposal

The issuance of shares of Common Stock upon exercise of the Common Warrants and Amended Warrants will have a dilutive effect on current stockholders. The percentage ownership of the Company held by current stockholders will decline as a result of the issuance of the shares of Common Stock underlying the Common Warrants and Amended Warrants. This means also that our current stockholders will own a smaller percent interest in us as a result of the exercise of the Common Warrants and Amended Warrants and therefore have less ability to influence significant corporate decisions requiring stockholder approval. Dilution of equity interests could also cause prevailing market prices for our Common Stock to decline. If the Common Warrants are exercised in full for cash, a total of 3,529,420 shares of Common Stock will be issuable to the holders of the Common Warrants, and this dilutive effect may be material to current stockholders of the Company. In addition, holders of the Amended Warrants are more likely to exercise such warrants than the Existing Warrants and therefore, the issuance of up to 1,647,088 shares of Common Stock upon the exercise of the Amended Warrants may further dilute the ownership of existing stockholders.

There may be future sales of our Common Stock, which could adversely affect the market price of our Common Stock. The exercise of any warrants, and other issuances of our Common Stock could have an adverse effect on the market price of the shares of our Common Stock. Sales of a substantial number of shares of our Common Stock or the perception that such sales might occur could materially adversely affect the market price of the shares of our Common Stock.

Provisions of the Common Warrants could discourage an acquisition of us by a third party. Certain provisions of the Common Warrants could make it more difficult or expensive for a third party to acquire us. The Common Warrants provide that, in the event of certain transactions constituting fundamental transactions, holders of such warrants will have the right, at their option, to receive from us or a successor entity the kind and amount of securities, cash or other property that such holder would have received had they exercised the Common Warrants immediately prior to the fundamental transaction. These and other provisions of the Common Warrants could prevent or deter a third party from acquiring us even where the acquisition could be beneficial to the holders of our Common Stock.

Other

The Stock Issuance and Warrant Proposal is separate from and unrelated to, and is not contingent upon, the Reverse Stock Split Proposal and the Adjournment Proposal.

Required Vote

Approval of this proposal requires the affirmative vote of a majority of the votes cast by the holders of all of the shares of Common Stock present or represented by proxy at the Special Meeting, provided that shares of Common Stock issued in connection with the registered direct offering that closed on April 4, 2025, will be excluded for purposes of counting the votes cast but included for purposes of quorum requirement.

THE BOARD OF DIRECTORS RECOMMENDS THAT STOCKHOLDERS VOTE "FOR"

THE APPROVAL OF ISSUANCE OF COMMON STOCK UNDERLYING THE COMMON WARRANTS AND AMENDED WARRANTS AS SET FORTH IN PROPOSAL 1.

Proposal 2

REVERSE STOCK SPLIT PROPOSAL

Background

Our Board has unanimously approved a series of alternate amendments to our Certificate of Incorporation, which would effect a reverse stock split of all issued and outstanding shares of our Common Stock, at a ratio ranging from 1-for-6 to 1-for-20, inclusive (the “Reverse Stock Split”).

Accordingly, effecting the Reverse Stock Split would reduce the number of outstanding shares of our Common Stock. The effectiveness of any one of these amendments and the abandonment of the other amendments, or the abandonment of all of these amendments, will be determined by our Board following the Special Meeting and prior to July 31, 2025. Our Board has recommended that these proposed amendments be presented to our stockholders for approval.

Our stockholders are being asked to approve these proposed amendments pursuant to Proposal 2, and to grant authorization to our Board to determine, at its option, whether to implement the Reverse Stock Split, including its specific timing and ratio.

Should we receive the required stockholder approvals for Proposal 2, our Board will have the sole authority to elect, at any time on or prior to July 31, 2025, and without the need for any further action on the part of our stockholders, whether to effect the Reverse Stock Split and the number of whole shares of our Common Stock, between and including 6 and 20, that will be combined into one share of our Common Stock.

Notwithstanding approval of Proposal 2 by our stockholders, our Board may, at its sole option, abandon the proposed amendments and determine prior to the effectiveness of any filing with the Secretary of State of the State of Delaware not to effect any Reverse Stock Split, as permitted under Section 242(c) of the General Corporation Law of the State of Delaware. If our Board does not implement the Reverse Stock Split on or prior to July 31, 2025, stockholder approval would again be required prior to implementing any reverse stock split.

By approving Proposal 2, our stockholders will: (a) approve a series of alternate amendments to our Certificate of Incorporation pursuant to which any whole number of outstanding shares of Common Stock between and including 6 and 20 could be combined into one share of Common Stock; and (b) authorize our Board to file only one such amendment, as determined by the Board at its sole option, and to abandon each amendment not selected by the Board. Our Board may also elect not to undertake any Reverse Stock Split and therefore abandon all amendments.

Approval of Reverse Stock Split of Our Common Stock

Our Board has adopted and is recommending that our stockholders approve a series of alternate amendments to our Certificate of Incorporation to effect the Reverse Stock Split. The text of the proposed form of Certificate of Amendment to our Certificate of Incorporation (the “Certificate of Amendment”) is attached hereto as Appendix A.

We are proposing that our Board have the discretion to select the Reverse Stock Split ratio from within a range between and including 1-for-6 and 1-for-20, rather than proposing that stockholders approve a specific ratio at this time, in order to give our Board the flexibility to implement the Reverse Stock Split at a ratio that reflects the Board’s then-current assessment of the factors described below under “Criteria to be Used for Determining Whether to Implement the Reverse Stock Split.” If the Board decides to implement the Reverse Stock Split, we will file the Certificate of Amendment with the Secretary of State of the State of Delaware and the Reverse Stock Split will be effective at 5:01 p.m., Eastern Time, on the date of filing of a Certificate of Amendment with the office of the Secretary of State of the State of Delaware, or such later date as is chosen by the Board and set forth in the Certificate of Amendment. Except for adjustments that may result from the treatment of fractional shares as described below, each of our stockholders will hold the same percentage of our outstanding Common Stock immediately following the Reverse Stock Split as such stockholder holds immediately prior to the Reverse Stock Split.

Reasons for Effecting the Reverse Stock Split

To maintain our listing on The Nasdaq Capital Market. By potentially increasing our stock price, the Reverse Stock Split would reduce the risk that our Common Stock could be delisted from The Nasdaq Capital Market. Our Common Stock is publicly traded and listed on Nasdaq under the symbol “APVO.” To continue our listing on The Nasdaq Capital Market, we must comply with Nasdaq Marketplace Rules, which requirements include the Bid Price Requirement. On June 25, 2024, we received a letter from Nasdaq notifying us that, for the last 30 consecutive business days, the bid price of our Common Stock had closed below $1.00 per share. On December 3, 2024, we filed a Certificate of Amendment to our Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a 1-for-37 reverse stock split of our outstanding Common Stock. The December 2024 Reverse Stock Split became effective on December 3, 2024 at 5:01 p.m. Eastern Time, and our Common Stock began trading on The Nasdaq Capital Market, on a split-adjusted basis, at market open on December 4, 2024. On December 18, 2024, we received notification from Nasdaq that for ten consecutive business days, the closing bid price of our Common Stock was at least $1.00 per share, and accordingly, we regained compliance with the Bid Price Requirement, and that the matter is now closed. Pursuant to Nasdaq Listing Rule 5810(c)(3)(A)(iv), we will not be eligible for any compliance period specified in Nasdaq Listing Rule 5810(c)(3)(A) if we have effected a reverse stock split over the prior one-year period or have effected one or more reverse stock splits over the prior two-year period with a cumulative ratio of 250 shares or more to one. The December 2024 Reverse Stock Split, when combined with the 1-for-44 reverse stock split previously effectuated on March 5, 2024, have effectuated a cumulative reverse stock split with a cumulative ratio of 250 shares or more to one. As a result, if we fail to meet the Bid Price Requirement within the two-year period after March 5, 2024, we would be subject to delisting by Nasdaq without any opportunity for a cure period. The Board has considered the potential harm to us and our stockholders should Nasdaq delist our Common Stock from The Nasdaq Capital Market. Delisting would likely reduce the visibility, liquidity, and value of our Common Stock, reduce institutional investor interest in our company, and may increase the volatility of our Common Stock. Alternatives, such as the OTC Bulletin Board and the pink sheets, are generally considered to be less efficient markets. An investor likely would find it less convenient to sell, or to obtain accurate quotations in seeking to buy, our Common Stock on an over-the-counter market. Many investors likely would not buy or sell our Common Stock due to difficulty in accessing over-the-counter markets, policies preventing them from trading in securities not listed on a national exchange, transaction costs that represent a higher percentage of total share value than would be the case if our share price were higher or for other reasons. Delisting could also cause a loss of confidence of potential industry partners, lenders, and employees, which could further harm our business and our future prospects.

The Board believes that the proposed Reverse Stock Split is a potentially effective means for us to continue to maintain compliance with the Bid Price Requirement and to avoid, or at least mitigate, the likely adverse consequences of our Common Stock being delisted from The Nasdaq Capital Market by producing the immediate effect of increasing the bid price of our Common Stock.

To potentially improve the marketability and liquidity of our Common Stock. Our Board believes that the increased market price of our Common Stock expected as a result of implementing the Reverse Stock Split could improve the marketability and liquidity of our Common Stock and encourage interest and trading in our Common Stock.

To provide greater flexibility to issue shares of Common Stock in connection with possible future financings. The Reverse Stock Split would have the effect of increasing the number of shares of Common Stock available for issuance under our Certificate of Incorporation. The Board believes that such an increase is in our stockholders’ best interests

as it would provide us with greater flexibility to issue shares of Common Stock in connection with possible future financings as well as under our equity incentive plans and for other general corporate purposes.

Criteria to be Used for Determining Whether to Implement Reverse Stock Split

In determining whether to implement the Reverse Stock Split and which Reverse Stock Split ratio to implement, if any, following receipt of stockholder approval of Proposal 2, our Board may consider, among other things, various factors, such as:

Certain Risks and Potential Disadvantages Associated with Reverse Stock Split

We cannot assure you that the proposed Reverse Stock Split will increase our stock price and have the desired effect of maintaining compliance with Nasdaq Marketplace Rules. We expect that the Reverse Stock Split will increase the market price of our Common Stock so that we may be able to maintain compliance with the Nasdaq Bid Price Requirement. However, the effect of the Reverse Stock Split upon the market price of our Common Stock cannot be predicted with any certainty, and the history of similar reverse stock splits for companies in like circumstances is varied, particularly since some investors may view a reverse stock split negatively. It is possible that the per share price of our Common Stock after the Reverse Stock Split will not rise in proportion to the reduction in the number of shares of our Common Stock outstanding resulting from the Reverse Stock Split, and the Reverse Stock Split may not result in a per share price that would attract brokers and investors who do not trade in lower priced stocks. In addition, Nasdaq Listing Rule 5810(c)(3)(A)(iv) states that any listed company that fails to meet the Bid Price Requirement after effecting a reverse stock split over the prior one-year period or having effected one or more reverse stock splits over the prior two-year period with a cumulative ratio of 250 shares or more to one would not be eligible for a compliance period to regain compliance and would be subject to delisting by Nasdaq. The December 2024 Reverse Stock Split, when combined with the 1-for-44 reverse stock split previously effectuated on March 5, 2024, have effectuated a cumulative reverse stock split with a cumulative ratio of 250 shares or more to one. As a result, if we fail to meet the Bid Price Requirement within the two-year period after March 5, 2024, we would be subject to delisting by Nasdaq without any opportunity for a cure period. Although we believe the Reverse Stock Split may enhance the desirability of our common stock to certain potential investors, we cannot assure you that, if implemented, our Common Stock will be more attractive to institutional and other long-term investors. Even if we implement the Reverse Stock Split, the market price of our Common Stock may decrease due to factors unrelated to the Reverse Stock Split. In any case, the market price of our Common Stock may also be based on other factors which may be unrelated to the number of shares outstanding, including our future performance. If the Reverse Stock Split is consummated and the trading price of our Common Stock declines, the percentage decline as an absolute number and as a percentage of our overall market capitalization may be greater than would occur in the absence of the Reverse Stock Split. Even if the market price of our Common Stock remains in excess of $1.00 per share, we may be delisted due to a failure to meet other continued listing requirements, including Nasdaq requirements related to the minimum

number of shares that must be in the public float, the minimum market value of the public float, minimum equity and the minimum number of “round lot” holders.

The proposed Reverse Stock Split may decrease the liquidity of our Common Stock and result in higher transaction costs. The liquidity of our Common Stock may be negatively impacted by the Reverse Stock Split, given the reduced number of shares that would be outstanding after the Reverse Stock Split, particularly if the stock price does not increase as a result of the Reverse Stock Split. In addition, if the Reverse Stock Split is implemented, it will increase the number of our stockholders who own “odd lots” of fewer than 100 shares of common stock. Brokerage commission and other costs of transactions in odd lots are generally higher than the costs of transactions of more than 100 shares of common stock. Accordingly, the Reverse Stock Split may not achieve the desired results of increasing marketability and liquidity of our Common Stock described above.

Effects of Reverse Stock Split

After the effective date of any Reverse Stock Split that our Board elects to implement, each stockholder will own a reduced number of shares of Common Stock. However, any Reverse Stock Split will affect all of our stockholders uniformly and will not affect any stockholder’s percentage ownership interests in Aptevo, except to the extent that the Reverse Stock Split results in any of our stockholders owning a fractional share as described below. Voting rights and other rights and preferences of the holders of our Common Stock will not be affected by the Reverse Stock Split (other than as a result of the payment of cash in lieu of fractional shares). For example, a holder of 2% of the voting power of the outstanding shares of our Common Stock immediately prior to the Reverse Stock Split would continue to hold 2% (assuming there is no impact as a result of the payment of cash in lieu of issuing fractional shares) of the voting power of the outstanding shares of our Common Stock immediately after such Reverse Stock Split. The number of stockholders of record will not be affected by the Reverse Stock Split (except to the extent that any stockholder holds only a fractional share interest and receives cash for such interest after such Reverse Stock Split).

The principal effects of the Reverse Stock Split will be that:

The following table contains approximate information, based on share information as of April 4, 2025, relating to our outstanding Common Stock based on the proposed Reverse Stock Split ratios (without giving effect to the treatment of fractional shares):

(1) The pre-reverse stock split pro-forma number of shares of common stock issued and outstanding includes:

• 3,223,214 shares of Common Stock issued and outstanding on April 4, 2025;

• 6,776,786 shares of Common Stock from future issuances that we have a reasonable basis to believe that such issuances will occur between the date of this proxy statement and the effective date of any Reverse Stock Split.

(2) The pre-reverse stock split number of shares of common stock reserved for future issuance includes the following:

• 328 shares of Common Stock issuable upon the exercise of stock options outstanding at a weighted average exercise price of $20,772.78 per share;

• 1,793 shares of Common Stock issuable upon the vesting of outstanding restricted stock units at a weighted average fair value per unit of $65.10 per share;

• 2,856 shares of Common Stock reserved for future grants of equity-based awards under our equity incentive plans;

• 39 shares of Common Stock issuable upon the exercise of Series A common warrants at an exercise price of $1,009.36 per share;

• 711 aggregate shares of Common Stock issuable upon the exercise of Series A-1, Series A-2 and Series B-2 common warrants, respectively, at an exercise price of $379.32 per share;

• 3,608 shares of Common Stock issuable upon the exercise of common warrants at an exercise price of $49.95 per share;

• 19,695 shares of Common Stock issuable upon the exercise of common warrants at an exercise price of $8.60 per share; and

• 5,176,508 shares of Common Stock issuable upon the exercise of common warrants at an exercise price of $1.19 per share.

After the effective date of any Reverse Stock Split that our Board elects to implement, our Common Stock would have a new committee on uniform securities identification procedures, or CUSIP number, a number used to identify our Common Stock. Stock certificates with the older CUSIP numbers will need to be exchanged for stock certificates with the new CUSIP numbers by following the procedures described below.

Our Common Stock is currently registered under Section 12(b) of the Exchange Act, and we are subject to the periodic reporting and other requirements of the Exchange Act. The implementation of any proposed Reverse Stock Split will not affect the registration of our Common Stock under the Exchange Act. Our Common Stock would continue to be listed on The Nasdaq Capital Market under the symbol “APVO” immediately following the Reverse Stock Split, although it is likely that Nasdaq would add the letter “D” to the end of the trading symbol for a period of twenty trading days after the effective date of the Reverse Stock Split to indicate that the Reverse Stock Split had occurred.

Our directors and executive officers have no substantial interests, directly or indirectly, in the matters set forth in the Reverse Stock Split, except to the extent of their ownership in shares of our Common Stock and securities exercisable for our Common Stock, which shares and securities would be subject to the same proportionate adjustment in

accordance with the terms of the Reverse Stock Split as all other outstanding shares of our Common Stock and securities exercisable for our Common Stock.

By increasing the number of authorized but unissued shares of Common Stock, the Reverse Stock Split could, under certain circumstances, have an anti-takeover effect, although this is not the intent of the Board. For example, the Board might be able to delay or impede a takeover or transfer of control of our company by causing such additional authorized but unissued shares to be issued to holders who might side with the Board in opposing a takeover bid that the Board determines is not in the best interests of our Company or our stockholders. The Reverse Stock Split could therefore have the effect of discouraging unsolicited takeover attempts. By potentially discouraging initiation of any such unsolicited takeover attempts the Reverse Stock Split could limit the opportunity for our stockholders to dispose of their shares at the higher price generally available in takeover attempts or that may be available under a merger proposal. The Reverse Stock Split could have the effect of permitting our current management, including our current Board, to retain its position, and place it in a better position to resist changes that stockholders may wish to make if they are dissatisfied with the conduct of our business. However, other than as previously disclosed, our Board is not aware of any attempt to take control of the Company and the Board did not authorize the Reverse Stock Split with the intent that it be utilized as a type of anti-takeover device.

Effective Date

The proposed Reverse Stock Split would become effective at 5:01 p.m., Eastern Time, on the date of filing of a Certificate of Amendment with the office of the Secretary of State of the State of Delaware, or such later date as is chosen by the Board and set forth in the Certificate of Amendment (the “Effective Date”). Except as explained below with respect to fractional shares, effective as of 5:01 p.m., Eastern Time, on the Effective Date, shares of Common Stock issued and outstanding immediately prior thereto will be combined, automatically and without any action on the part of us or our stockholders, into a lesser number of new shares of our Common Stock in accordance with the Reverse Stock Split ratio determined by our Board within the limits set forth in this Proposal 2.

Cash Payment In Lieu of Fractional Shares

No fractional shares of Common Stock will be issued as a result of any Reverse Stock Split. Instead, in lieu of any fractional shares to which a stockholder of record would otherwise be entitled as a result of the Reverse Stock Split, we will pay cash (without interest) equal to such fraction multiplied by the average of the closing sales prices of our Common Stock on The Nasdaq Capital Market during regular trading hours for the five consecutive trading days immediately preceding the Effective Date (with such average closing sales prices being adjusted to give effect to the Reverse Stock Split). After the Reverse Stock Split, a stockholder otherwise entitled to a fractional interest will not have any voting, dividend or other rights with respect to such fractional interest except to receive payment as described above.

As of April 4, 2025, there were approximately 8 stockholders of record of our Common Stock. Upon stockholder approval of this Proposal 2, if our Board elects to implement the proposed Reverse Stock Split, stockholders owning, prior to the Reverse Stock Split, less than the number of whole shares of Common Stock that will be combined into one share of common stock in the Reverse Stock Split would no longer be stockholders. For example, if a stockholder held four shares of common stock immediately prior to the Reverse Stock Split and the Reverse Stock Split ratio selected by the Board was 1-for-6, then such stockholder would cease to be a stockholder of Aptevo following the Reverse Stock Split and would not have any voting, dividend or other rights except to receive payment for the fractional share as described above. As to any fraction of a share which a stockholder of record would otherwise be entitled to purchase upon exercise of a common warrant, we will, at our discretion, either pay a cash adjustment in an amount equal to such fraction multiplied by the exercise price or round the fractional value up to the next whole value. If a stockholder held common warrants which entitles such stockholder to purchase 55 shares of Common Stock at an exercise price of $1.19 per share prior to the Reverse Stock Split and the Reverse Stock Split ratio selected by the Board was 1-for-6, then such stockholder is entitled to receive either, at our discretion, a cash adjustment of $1.19 and nine shares of Common Stock or receive ten shares of Common Stock upon exercise of warrants after the Reverse Stock Split. Based on our stockholders of record as of April 4, 2025, and assuming the Reverse Stock Split ratio of 1-for-6, we expect that cashing out fractional stockholders would not materially reduce the number of stockholders of record. In addition, we do not intend for this transaction to be the first step in a series of plans or proposals of a “going private transaction” within the meaning of Rule 13e-3 of the Exchange Act.

Procedure for Effecting the Reverse Stock Split and Exchange of Stock Certificates

If this Proposal 2 is approved by our stockholders and our Board elects to implement the Reverse Stock Split, we will file with the Secretary of State of the State of Delaware the Certificate of Amendment in the form attached hereto as Appendix A reflecting such Reverse Stock Split ratio determined by the Board. Beginning on the Effective Date, each certificate representing shares of Common Stock will be deemed for all corporate purposes to evidence ownership of the number of whole shares into which the shares previously represented by the certificate were combined pursuant to the Reverse Stock Split.

If this Proposal 2 is approved by our stockholders and our Board elects to implement the Reverse Stock Split, stockholders of record holding all of their shares of our Common Stock electronically in book-entry form under the direct registration system for securities will be automatically exchanged by the exchange agent and will receive a transaction statement at their address of record indicating the number of new post-split shares of our Common Stock they hold after the Reverse Stock Split along with payment in lieu of any fractional shares. Non-registered stockholders holding Common Stock through a bank, broker or other nominee should note that such banks, brokers or other nominees may have different procedures for processing the Reverse Stock Split and making payment for fractional shares than those that would be put in place by us for registered stockholders. If you hold your shares with such a bank, broker or other nominee and if you have questions in this regard, you are encouraged to contact your nominee.

If this Proposal 2 is approved by our stockholders and our Board elects to implement the Reverse Stock Split, stockholders of record holding some or all of their shares in certificate form will receive a letter of transmittal from us or our exchange agent, as soon as practicable after the Effective Date of the Reverse Stock Split. Our transfer agent is expected to act as “exchange agent” for the purpose of implementing the exchange of stock certificates. Holders of pre-Reverse Stock Split shares will be asked to surrender to the exchange agent certificates representing pre-Reverse Stock Split shares in exchange for post-Reverse Stock Split shares and payment in lieu of fractional shares (if any) in accordance with the procedures to be set forth in the letter of transmittal. No new post-Reverse Stock Split share certificates will be issued to a stockholder until such stockholder has surrendered such stockholder’s outstanding certificate(s) together with the properly completed and executed letter of transmittal to the exchange agent. Any old shares submitted for exchange, whether pursuant to a sale, other disposition or otherwise, will automatically be exchanged for new shares. Our Common Stock will also receive a new CUSIP number.

STOCKHOLDERS SHOULD NOT DESTROY ANY PRE-SPLIT STOCK CERTIFICATE AND SHOULD NOT SUBMIT ANY CERTIFICATES UNTIL THEY ARE REQUESTED TO DO SO.

Accounting Consequences

The par value per share of our Common Stock would remain unchanged at $0.001 per share after any Reverse Stock Split. As a result, on the Effective Date, the stated capital on our balance sheet attributable to our Common Stock would be reduced proportionally, based on the actual Reverse Stock Split ratio, from its present amount, and the additional paid-in capital account would be credited with the amount by which the stated capital would be reduced. The net income or loss per share of Common Stock would be increased because there would be fewer shares of Common Stock outstanding. The Reverse Stock Split would be reflected retroactively in certain of our consolidated financial statements. We do not anticipate that any other accounting consequences would arise as a result of any Reverse Stock Split.

Material Federal Income Tax Consequences

The following is a summary of the material U.S. federal income tax consequences of the Reverse Stock Split to our stockholders. The summary is based on the Internal Revenue Code of 1986, as amended, or the Code, applicable Treasury Regulations promulgated thereunder, judicial authority and current administrative rulings and practices as in effect on the date of this proxy statement. Changes to the laws could alter the tax consequences described below, possibly with retroactive effect. We have not sought and will not seek an opinion of counsel or a ruling from the Internal Revenue Service regarding the federal income tax consequences of the Reverse Stock Split. This discussion is for general information only and does not discuss the tax consequences which may apply to special classes of taxpayers (e.g., non-resident aliens, broker/dealers or insurance companies). The state and local tax consequences of the Reverse Stock Split may vary significantly as to each stockholder, depending upon the jurisdiction in which such stockholder resides. Stockholders are urged to consult their own tax advisors to determine the particular consequences to them.

In general, the federal income tax consequences of the Reverse Stock Split will vary among stockholders depending upon whether they receive cash for fractional shares or solely a reduced number of shares of common stock in exchange for their old shares of common stock. We believe that because the Reverse Stock Split is not part of a plan to increase periodically a stockholder’s proportionate interest in our assets or earnings and profits, the Reverse Stock Split should have the following federal income tax effects. A stockholder who receives solely a reduced number of shares of common stock will not recognize gain or loss. In the aggregate, such a stockholder’s basis in the reduced number of shares of common stock will equal the stockholder’s basis in its old shares of common stock and such stockholder’s holding period in the reduced number of shares will include the holding period in its old shares exchanged. A stockholder who receives cash in lieu of a fractional share as a result of the Reverse Stock Split should generally be treated as having received the payment as a distribution in redemption of the fractional share, as provided in Section 302(a) of the Code. Generally, if redemption of the fractional shares of all stockholders reduces the percentage of the total voting power held by a particular redeemed stockholder (determined by including the voting power held by certain related persons), the particular stockholder should recognize gain or loss equal to the difference, if any, between the amount of cash received and the stockholder’s basis in the fractional share. In the aggregate, such a stockholder’s basis in the reduced number of shares of common stock will equal the stockholder’s basis in its old shares of common stock decreased by the basis allocated to the fractional share for which such stockholder is entitled to receive cash, and the holding period of the reduced number of shares received will include the holding period of the old shares exchanged. If the redemption of the fractional shares of all stockholders leaves the particular redeemed stockholder with no reduction in the stockholder’s percentage of total voting power (determined by including the voting power held by certain related persons), it is likely that cash received in lieu of a fractional share would be treated as a distribution under Section 301 of the Code. Stockholders should consult their own tax advisors regarding the tax consequences to them of a payment for fractional shares.

We will not recognize any gain or loss as a result of the proposed Reverse Stock Split.

No Appraisal Rights

Our stockholders are not entitled to dissenters’ or appraisal rights under the General Corporation Law of the State of Delaware with respect to the proposed alternate amendments to our Certificate of Incorporation to allow for the Reverse Stock Split.

Other

The Reverse Stock Split Proposal is separate from and unrelated to, and is not contingent upon, the Stock Issuance and Warrant Proposal and the Adjournment Proposal.

Required Vote

Stockholder approval of this Proposal 2 requires a “FOR” vote of a majority of the votes cast by the holders of all of the shares of Common Stock present or represented by proxy at the Special Meeting.

THE BOARD OF DIRECTORS RECOMMENDS THAT STOCKHOLDERS VOTE “FOR”

THE APPROVAL OF THE REVERSE STOCK SPLIT PROPOSAL.

Proposal 3

AUTHORIZATION TO ADJOURN THE SPECIAL MEETING

General

If the Special Meeting is convened and a quorum is present, but there are not sufficient votes to approve Proposal 1, or Proposal 2, our proxy holders may move to adjourn the Special Meeting at that time in order to enable our Board to solicit additional proxies in favor of each of the proposals.

In this proposal, we are asking our stockholders to authorize the holder of any proxy solicited by our Board, and each of them individually, to vote to adjourn the Special Meeting to another time and place, if necessary, to solicit additional proxies in the event there are not sufficient votes to approve Proposal 1 or Proposal 2. If our stockholders approve this proposal, we could adjourn, postpone or continue the Special Meeting and any adjourned session of the Special Meeting to use the additional time to solicit additional proxies, including the solicitation of proxies from our stockholders that have previously voted against Proposal 1 or Proposal 2. Among other things, approval of this proposal could mean that, even if we had received proxies representing a sufficient number of votes to defeat Proposal 1 or Proposal 2, we could adjourn the Special Meeting without a vote on such proposal(s) and seek to convince our stockholders to change their votes in favor of such proposal(s).

If it is necessary or appropriate to adjourn the Special Meeting, no notice of the adjourned meeting is required to be given to our stockholders, other than an announcement at the Special Meeting of the time and place to which the Special Meeting is adjourned, so long as the meeting is adjourned for 30 days or less and no new record date is fixed for the adjourned meeting. At the adjourned meeting, we may transact any business which might have been transacted at the original meeting.

Other Matters

The Adjournment Proposal is separate from and unrelated to, and is not contingent upon, the Stock Issuance and Warrant Proposal and the Reserve Stock Split Proposal.

Required Vote

Approval of this proposal requires the affirmative vote of a majority of the votes cast by the holders of all of the shares of Common Stock present or represented by proxy at the Special Meeting.

THE BOARD OF DIRECTORS RECOMMENDS THAT STOCKHOLDERS VOTE "FOR"

THE AUTHORIZATION TO ADJOURN THE SPECIAL MEETING AS SET FORTH IN

PROPOSAL 3.

Security Ownership of Certain Beneficial Owners and Management

The following table sets forth certain information regarding the ownership of our Common Stock as of April 4, 2025 by: (i) each director and nominee for director; (ii) each of the named executive officers; (iii) all named executive officers and directors of our company as a group; and (iv) all those known by us to be beneficial owners of more than five percent of its Common Stock. Unless otherwise indicated, the address of the individuals and entities below is c/o Aptevo Therapeutics Inc., 2401 4th Avenue, Suite 1050, Seattle, Washington 98121.

Beneficial ownership is determined in accordance with the rules of the SEC. These rules generally attribute beneficial ownership of securities to persons who possess sole or shared voting power or investment power with respect to those securities and include shares of Common Stock issuable upon the exercise of stock options that are immediately exercisable or exercisable and vesting restricted stock units (“RSU”) within 60 days after April 4, 2025 but exclude unvested stock options. The information is not necessarily indicative of beneficial ownership for any other purpose.

In computing the number of shares of Common Stock beneficially owned by a person and the percentage ownership of that person, we deemed outstanding shares of Common Stock subject to options or RSUs held by that person that are currently exercisable or exercisable within 60 days of April 4, 2025. We did not deem these shares outstanding, however, for the purpose of computing the percentage ownership of any other person.

* Less than one percent.

(1) This table is based upon information supplied by officers and directors. The Company's principal stockholders who own 5% or more of our outstanding Common Stock are based on most recently filed Schedules 13D, 13G or based on our knowledge. Unless otherwise indicated in the footnotes to this table and subject to community property laws where applicable, we believe that each of the stockholders named in this table has sole voting and investment power with respect to the shares indicated as beneficially owned. Applicable percentages are based on 3,223,214 shares outstanding on April 4, 2025, adjusted as required by rules promulgated by the SEC. Each person is deemed to be the beneficial owner of shares which may be acquired within sixty days of April 4, 2025, through the exercise of options, warrants, and other rights, if any.

(2) Includes 100 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(3) Includes 48 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(4) Includes 23 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(5) Includes 10 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(6) Includes 10 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(7) Includes 10 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(8) Includes 10 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(9) Includes 10 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(10) Includes 240 shares of Common Stock issuable upon the exercise of options that are exercisable and vesting RSUs on or within 60 days of April 4, 2025.

(11) Beneficial ownership shares and the related ownership percentage are as of April 4, 2025, and based on our knowledge, from a registered direct offering completed by the Company on April 4, 2025.

(12) Based on Schedule 13G filed on April 8, 2025, by Bigger Capital Fund LP ("Bigger Capital"), Bigger Capital Fund GP, LLC ("Bigger GP"), and Michael Bigger, which states that as of April 3, 2025, the reporting persons have shared voting power and shared dispositive power over 200,000 shares of Common Stock. Bigger GP, as the general partner of Bigger Capital, may be deemed to beneficially own the 200,000 shares of Common Stock. Mr. Bigger, as the managing member of Bigger GP, may be deemed to beneficially own the 200,000 shares of Common Stock beneficially owned by Bigger Capital. Each of Bigger GP and Mr. Bigger disclaims beneficial ownership of the shares of Common Stock beneficially owned by Bigger Capital. Does not include 859,776 shares of Common Stock issuable upon the exercise of common warrants, the exercise of which is subject to a 4.99% beneficial ownership limitation. The address of the reporting persons is 11700 W Charleston Blvd. 170-659, Las Vegas, NV 89135.

(13) Based on Schedule 13G filed on April 10, 2025, by CVI Investments, Inc. ("CVI") and Heights Capital Management, Inc., which states that as of April 4, 2025, the reporting persons have shared voting power and dispositive power over 200,000 shares of Common Stock. Heights Capital Management, Inc., serving as the investment manager to CVI, may be deemed to be the beneficial owner of the 200,000 shares of Common Stock held by CVI. Each of the reporting persons disclaims any beneficial ownership of such securities, except for their pecuniary interest therein. Does not include 400,000 shares of Common Stock issuable upon the exercise of common warrants, the exercise of which is subject to a 4.99% beneficial ownership limitation. The address of CVI is PO Box 309GT, Ugland House, South Church Street, George Town, Grand Cayman, KY1-1104 Cayman Islands. The address of Heights Capital Management, Inc. is 101 California Street, Suite 3250, San Francisco, California 94111.

(14) Based on Schedule 13G filed on April 7, 2025, by L1 Capital Global Opportunities Master Fund, Ltd. ("L1 Capital"), which states that as of April 4, 2025, the reporting person has sole voting power and sole dispositive power over 200,000 shares of Common Stock. David Feldman and Joel Arber are the directors of L1 Capital. As such, L1 Capital, Mr. Feldman, and Mr. Arber may be deemed to beneficially own the 200,000 shares of Common Stock. To the extent Mr. Feldman and Mr. Arber are deemed to beneficially own such securities, Mr. Feldman and Mr. Arber disclaim beneficial ownership of these securities for all other purposes. Does not include 400,000 shares of Common Stock issuable upon the exercise of common warrants, the exercise of which is subject to a 4.99% beneficial ownership limitation. The address of the reporting person is 161A Shedden Road, 1 Artillery Court, PO Box 10085 Grand Cayman, Cayman Islands KY1-1001.

Householding of Proxy Materials

The SEC has adopted rules that permit companies and intermediaries (e.g., brokers) to satisfy the delivery requirements for Notices of Internet Availability of Proxy Materials or other Special Meeting materials with respect to two or more stockholders sharing the same address by delivering a single proxy statement or other Special Meeting materials addressed to those stockholders. This process, which is commonly referred to as “householding,” potentially means extra convenience for stockholders and cost savings for companies.

This year, a number of brokers with account holders who are Aptevo stockholders will be "householding" the Company’s proxy materials. A single proxy statement and proxy card will be delivered to multiple stockholders sharing an address unless contrary instructions have been received from the affected stockholders. Once you have received notice from your broker that they will be “householding” communications to your address, “householding” will continue until you are notified otherwise or until you revoke your consent. If, at any time, you no longer wish to participate in “householding” and would prefer to receive a separate proxy statement, please notify your broker or Aptevo. Direct your written request to Aptevo Therapeutics Inc., Attn: SoYoung Kwon, Corporate Secretary, 2401 4th Avenue, Suite 1050, Seattle, Washington 98121 or contact SoYoung Kwon at (206) 496-3966. Stockholders who currently receive multiple copies of the proxy statement at their addresses and would like to request “householding” of their communications should contact their brokers.

Incorporation of Certain Information by Reference

The SEC allows us to incorporate by reference into this proxy statement information contained in documents that we file with it. The information incorporated by reference is deemed to be part of this proxy statement. Any statement contained in this proxy statement or a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this proxy statement to the extent that a statement contained in this prospectus or a subsequently filed document incorporated by reference modifies or replaces that statement.

This proxy statement incorporates by reference the documents set forth below that have previously been filed with the SEC, other than portions of these documents that are furnished under Item 2.02 or Item 7.01 of a Current Report on Form 8-K:

In addition, all reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act will also be deemed to be incorporated by reference into this proxy statement and deemed to be part of this proxy statement from the date of the filing of such reports and documents.

Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this proxy statement to the extent that a statement contained herein or in any subsequently filed document that also is or is deemed to be incorporated by reference herein, as the case may be, modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this proxy statement.

We undertake to provide without charge to each person to whom a copy of this proxy statement has been delivered, upon request, by first class mail or other equally prompt means, a copy of any or all of the documents incorporated by reference in this proxy statement, other than the exhibits to these documents, unless the exhibits are specifically incorporated by reference into the information that this proxy statement incorporates. You may obtain documents incorporated by reference by directing requests for documents to:

Aptevo Therapeutics Inc.

2401 4th Avenue, Suite 1050

Seattle, WA 98121

Attn: General Counsel

(206) 838-0500

Other Matters

The Board knows of no other matters that will be presented for consideration at the Special 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 such matters in accordance with their best judgment.

Forward-Looking Statements

This Proxy Statement contains a number of "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on management’s current expectations, estimates, projections and beliefs, as well as a number of assumptions concerning future events. When used in this Proxy Statement, the words "estimates," "projected," "expects," "anticipates," "forecasts," "plans," "intends," "believes," "seeks," "may," "will," "should," "future," "propose" and variations of these words or similar expressions (or the negative versions of such words or expressions) are intended to identify forward-looking statements.

Websites

The information contained on the websites referenced in this Proxy Statement are not incorporated by reference into this Proxy Statement. Further, references to website URLs are intended to be inactive textual references only.

Appendix A

CERTIFICATE OF AMENDMENT OF THE
AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF
APTEVO THERAPEUTICS INC.

APTEVO THERAPEUTICS Inc., a corporation organized and existing under the laws of the State of Delaware, hereby certifies as follows:

First: The name of this corporation is Aptevo Therapeutics Inc. (the “Company”).

Second: The date on which the Company’s Certificate of Incorporation was originally filed with the Secretary of State of the State of Delaware is February 22, 2016.

Third: The Board of Directors of the Company, acting in accordance with the provisions of Section 242 of the General Corporation Law of the State of Delaware, adopted resolutions amending its Amended and Restated Certificate of Incorporation, as heretofore amended (the “Certificate of Incorporation”), by adding the following at the end of the first paragraph of Article FOURTH of the Certificate of Incorporation:

“Effective as of the effective time of 5:01 p.m., Eastern time, on , 2025 (the “2025 Reverse Split Effective Time”), 1-for-6 to 1-for-20) shares of the Company’s Common Stock, par value $0.001 per share, issued and outstanding immediately prior to the 2025 Reverse Split Effective Time shall, automatically and without any action on the part of the Company or the respective holders thereof, be combined into one (1) share of Common Stock without increasing or decreasing the par value of each share of Common Stock (the “2025 Reverse Split”); provided, however, no fractional shares of Common Stock shall be issued as a result of the 2025 Reverse Split and, in lieu thereof, upon receipt after the 2025 Reverse Split Effective Time by the exchange agent selected by the Company of a properly completed and duly executed transmittal letter and, where shares are held in certificated form, the surrender of the stock certificate(s) formerly representing shares of pre-2025 Reverse Split Common Stock, any stockholder who would otherwise be entitled to a fractional share of post-2025 Reverse Split Common Stock as a result of the 2025 Reverse Split, following the 2025 Reverse Split Effective Time (after taking into account all fractional shares of post-2025 Reverse Split Common Stock otherwise issuable to such stockholder), shall be entitled to receive a cash payment (without interest) equal to the fractional share of post-2025 Reverse Split Common Stock to which such stockholder would otherwise be entitled multiplied by the average of the closing sales prices of a share of the Company’s Common Stock (as adjusted to give effect to the 2025 Reverse Split) on The Nasdaq Capital Market during regular trading hours for the five (5) consecutive trading days immediately preceding the date this Certificate of Amendment is filed with the Secretary of State of the State of Delaware. Each stock certificate that, immediately prior to the 2025 Reverse Split Effective Time, represented shares of pre-2025 Reverse Split Common Stock shall, from and after the 2025 Reverse Split Effective Time, automatically and without any action on the part of the Company or the respective holders thereof, represent that number of whole shares of post-2025 Reverse Split Common Stock into which the shares of pre-2025 Reverse Split Common Stock represented by such certificate shall have been combined (as well as the right to receive cash in lieu of any fractional shares of post-2025 Reverse Split Common Stock as set forth above); provided, however, that each holder of record of a certificate that represented shares of pre-2025 Reverse Split Common Stock shall receive, upon surrender of such certificate, a new certificate representing the number of whole shares of post-2025 Reverse Split Common Stock into which the shares of pre-2025 Reverse Split Common Stock represented by such certificate shall have been combined pursuant to the 2025 Reverse Split, as well as any cash in lieu of fractional shares of post-2025 Reverse Split Common Stock to which such holder may be entitled as set forth above. The 2025 Reverse Split shall be effected on a record holder-by-record holder basis, such that any fractional shares of post-2025 Reverse Split Common Stock resulting from the 2025 Reverse Split and held by a single record holder shall be aggregated.”

Fourth: The foregoing amendment was submitted to the stockholders of the Company for their approval, and was duly adopted in accordance with the provisions of Section 242 of the General Corporation Law of the State of Delaware and shall be effective as of 5:01 p.m., Eastern time, on , 2025.

In Witness Whereof, Aptevo Therapeutics Inc. has caused this Certificate of Amendment to be signed by its President and Chief Executive Officer this day of , 2025.

SCAN TO VIEW MATERIALS & VOTE APTEVO THERAPEUTICS INC. C/O BROADRIDGE CORPORATE ISSUER SOLUTIONS 2401 FOURTH AVE., SUITE 1050 SEATTLE, WA 98121 VOTE BY INTERNET Before The Meeting - Go to www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 p.m. Eastern Time on April 30, 2025. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. During The Meeting - Go to www.virtualshareholdermeeting.com/APVO2025SM You may attend the meeting via the Internet and vote during the meeting. Have the information that is printed in the box marked by the arrow available and follow the instructions. VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions up until 11:59 p.m. Eastern Time on April 30, 2025. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: V69568-S13507 KEEP THIS PORTION FOR YOUR RECORDS THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. DETACH AND RETURN THIS PORTION ONLY APTEVO THERAPEUTICS INC. The Board of Directors recommends you vote FOR Proposals 1, 2 and 3: 1. To approve, in accordance with Nasdaq Listing Rule 5635(d), the issuance of more than 19.99% of the Company’s outstanding Common Stock, par value $0.001 per share (“Common Stock”), including (i) Common Stock issuable upon the exercise of the common warrants (the “Common Warrants”) For Against Abstain issued and sold in a private placement pursuant to that certain Securities Purchase Agreement, dated as of April 3, 2025, by and among the Company and purchasers thereto (the “Purchase Agreement”) and (ii) Common Stock issuable upon the exercise of those certain existing common warrants that were previously issued on December 12, 2024 to purchase 1,647,088 shares of Common Stock, and have an exercise price of $9.53 per share, that were amended in connection with the issuance of the Common Warrants (the “Amended Warrants”). 2. To approve an amendment to our Amended and Restated Certificate of Incorporation, as amended (“Certificate of Incorporation”), to effect a reverse stock split of our Common Stock, at a ratio in the range of 1-for-6 to 1-for-20, with such ratio to be determined in the discretion of our board of directors and with such reverse stock split to be effected at such time and date, if at all, as determined by our board of directors in its sole discretion. 3. To authorize an adjournment of the meeting to a later date or dates, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes in favor of Proposal 1 or Proposal 2. NOTE: Such other business as may properly come before the meeting or any adjournment or postponement thereof. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting: The Proxy Statement is available at www.proxyvote.com. V69569-S13507 APTEVO THERAPEUTICS INC. THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS SPECIAL MEETING OF STOCKHOLDERS MAY 1, 2025 at 10:00 AM, PACIFIC TIME The stockholder(s) hereby appoint(s) SoYoung Kwon and Daphne Taylor, or either of them, as proxies, each with the power to appoint her substitute, and hereby authorize(s) them to represent and to vote, as designated on the reverse side of this ballot, all of the shares of Common Stock of Aptevo Therapeutics Inc. that the stockholder(s) is/are entitled to vote at the virtual Special Meeting of Stockholders to be held at 10:00 a.m., Pacific Time on Wednesday, April 30, 2025, and any adjournment or postponement thereof. THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED AS DIRECTED BY THE STOCKHOLDER(S). IF NO SUCH DIRECTIONS ARE MADE, THIS PROXY WILL BE VOTED "FOR" PROPOSAL 1, PROPOSAL 2 AND PROPOSAL 3. IN THEIR DISCRETION, THESE PROXIES OF THE UNDERSIGNED ARE AUTHORIZED TO VOTE UPON ANY AND ALL OTHER MATTERS THAT MAY PROPERLY COME BEFORE THE MEETING. PLEASE MARK, SIGN, DATE AND RETURN THIS PROXY CARD PROMPTLY USING THE ENCLOSED REPLY ENVELOPE. CONTINUED AND TO BE SIGNED ON REVERSE SIDE