BioAtla, Inc.

We will mail, on or about June 5, 2026, the Notice of Internet Availability of Proxy Materials, or the Notice, to our stockholders of record and beneficial owners at the close of business on May 18, 2026. On the date of mailing of the Notice, all stockholders and beneficial owners will have the ability to access all of the proxy materials on a website referred to in the Notice. These proxy materials will be available free of charge.

The Notice will identify the website where the proxy materials will be made available; the date, the time and location of the Annual Meeting; the matters to be acted upon at the meeting and our board of directors’ recommendations with regard to each matter; a toll-free telephone number, an e-mail address, and a website where stockholders can request a paper or e-mail copy of the Proxy Statement; our Annual Report on Form 10-K for the fiscal year ended December 31, 2025 (as amended on Form 10-K/A, our “Annual Report on Form 10-K”), and a form of proxy relating to the Annual Meeting; information on how to access the form of proxy; and information on how to participate in the meeting and vote your shares for the matters acted upon at the meeting.

ADJUSTMENT FOR SHARE CONSOLIDATION

On April 6, 2026, we effected a 50-for-1 share consolidation of our issued and outstanding common stock (the “Share Consolidation”). Accordingly, all share and per share amounts for all periods presented in this Proxy Statement have been retroactively adjusted to reflect the Share Consolidation. In addition, all equity awards and warrants outstanding immediately prior to the Share Consolidation were proportionally adjusted.