Note 2. Collaboration Agreements

Niowave, Inc.

On May 25, 2026, our wholly owned subsidiary, Aptevo Research and Development LLC (“Aptevo R&D” or the “Company”), entered into a Collaboration Agreement (“Niowave Collaboration Agreement”) with Niowave, Inc. (“Niowave”) to develop

radiopharmaceutical product candidates combining our proprietary molecules with Niowave’s radioisotopes. Under the collaboration, we also entered into a Supply Agreement (“Supply Agreement”) under which Niowave will supply proprietary radioisotopes.

In connection with the execution of the Niowave Collaboration Agreement and the Supply Agreement, we entered into a stock purchase agreement (the “Stock Purchase Agreement”) pursuant to which Niowave purchased 98,522 shares of our common stock and accompanying warrants to purchase 53,201 shares of our common stock in a private placement at a combined purchase price of $5.075 per share for aggregate gross proceeds of $500,000. Each warrant is immediately exercisable, with an exercise price of $8.00 per share of common stock and will expire on May 25, 2031. The parties also entered into an investor rights agreement (the “Investor Rights Agreement”) customary lock-up, standstill, market stand-off, transfer restriction and registration rights provisions, including restrictions on transfers of the initial shares, certain acquisition or control activities, and ownership above 19.99% of the Company’s outstanding common stock. In addition, Niowave has the right, but not the obligation, to purchase up to 97,373 additional shares (the “Additional Share Purchase Right”) in the future at prevailing market prices, subject to specified conditions, and an aggregate beneficial ownership limitation of 19.99% of the Company’s outstanding common stock.

We assessed the Collaboration Agreement in accordance with ASC 606 – Revenue Recognition (“ASC 606”) and ASC 808 – Collaborative Arrangements (“ASC 808”) and concluded that the arrangement represents a collaborative arrangement rather than a revenue generating contract, as both parties are active participants sharing governance, risks, and rewards through a 50/50 cost and revenue sharing structure. The counterparty is not considered a customer under the arrangement. The counterparty is not considered a customer because the arrangement is collaborative in nature and does not involve the transfer of goods or services that are outputs of the Company’s ordinary activities in exchange for consideration. Accordingly, the arrangement is within the scope of ASC 808, and cost sharing reimbursements are recognized as a reduction of research and development expense in the period the related costs are incurred. For the six months ended June 30, 2026, the Company did not incur any costs under the Niowave Collaboration Agreement.

We also concluded that the Niowave Collaboration Agreement and related equity instruments should be accounted for separately. The Niowave Collaboration Agreement represents a single collaborative unit of account, while the common stock, common warrants and additional share purchase right (the “Additional Share Purchase Right”) represent freestanding financial instruments. The Additional Share Purchase Right is treated as a freestanding equity-classified instrument under ASC 815 – Derivatives and Hedging (“ASC 815”) and is not subsequently remeasured.

The Company measured the common stock issued in the transaction based on quoted market prices on the issuance date. The fair value of the common warrants was determined using a Black-Scholes option pricing model, which incorporates assumptions for expected volatility, term and risk-free interest rate. The Additional Share Purchase Right was evaluated as a freestanding instrument, and its fair value at inception was determined to be nominal, as the exercise price is based on the Company’s prevailing market price and does not provide an intrinsic economic benefit at issuance. Because the Additional Share Purchase Right was determined to have nominal fair value, the $500,000 in gross proceeds was allocated to the common stock and common warrants based on their relative fair values.

Alligator Bioscience AB

On July 20, 2017, we entered into a collaboration and option agreement (the “Alligator Collaboration Agreement”) with Alligator Bioscience AB (“Alligator”), pursuant to which Aptevo and Alligator have been collaboratively developing ALG.APV-527, a first-in-class bispecific antibody candidate simultaneously targeting 4-1BB (CD137), a member of the TNFR superfamily of a costimulatory receptor found on activated T cells, and 5T4, a tumor antigen widely overexpressed in a number of different types of cancer.

We assessed the arrangement in accordance with ASC 606 and concluded that the contract counterparty, Alligator, is not a customer because both parties are active participants in the development activities and share in the significant risks and rewards of the arrangement, rather than exchanging goods or services for consideration. As such the arrangement is not in the scope of ASC 606 and is instead treated as a collaborative agreement under ASC 808. Both Aptevo and Alligator are active participants in the development of ALG.APV-527 and are exposed to significant risks and rewards under the Alligator Collaboration Agreement. Amounts owed to us for Alligator's share of development costs incurred by the Company are recorded as a reduction of research and development expense under ASC 730 – Research and Development in the period the costs are incurred. For the six months ended June 30, 2026 and 2025, we recorded approximately $0.05 million and $0.2 million, which represents our 50% cost share, in our research and development expense related to the Alligator Collaboration Agreement, respectively.