ANAPTYSBIO INC

Entry into New Open Market Sales Agreement

In November 2024, we entered into a sales agreement with TD Securities (USA) LLC (“TD Cowen”), through which we may offer and sell shares of our common stock, having an aggregate offering of up to $100.0 million through TD Cowen as our sales agent. Our prior sales agreement with Cowen & Company, LLC will terminate upon effectiveness of the registration statement on the Form S-3 we will file in connection with our sales agreement with TD Cowen.

Rule 10b5-1 Trading Arrangements

On August 30, 2024, John Schmid, adirector of the company, entered into a written plan for the potential sale of up to an aggregate 42,337 shares of common stock. The aggregate number of shares that will be sold under the plan is not yet determinable because the shares available will be net of shares sold to satisfy tax withholding obligations that arise in connection with the vesting and settlement of any equity awards held by Mr. Schmid. As such, for purposes of this disclosure, the aggregate number of shares of common stock available for sale reflects the aggregate maximum number of shares underlying Mr. Schmid’s equity awards which may be sold, without excluding the shares that will be sold to satisfy the tax withholding obligations. The plan is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act and is scheduled to terminate no later than November 14, 2025.

The plan includes a representation from Mr. Schmid to the broker administering the plan that Mr. Schmid was not in possession of any material nonpublic information regarding the company or the securities subject to the plan. A similar representation was made to us in connection with the adoption of the plan under our Insider Trading Policy. Those representations were made as of the date of adoption of the plan and speak only as of that date. In making those representations, there is no assurance with respect to any material nonpublic information of which Mr. Schmid was unaware, or with respect to any material nonpublic information acquired by Mr. Schmid or the company after the date of the representation.

Other than as disclosed above, during the three months ended September 30, 2024, none of the company’s directors or officers adopted orterminated any “Rule 10b5-1 trading arrangements” or any “non-Rule 10b5-1 trading arrangements,” as each term is defined in Item 408 of Regulation S-K.