Amendment to Tax Benefit Preservation Plan

Seer, Inc. entered into Amendment No. 1 to its Tax Benefit Preservation Plan on March 13, 2026. This amendment clarifies the definition of "Beneficial Ownership" to align with Treasury Regulation § 1.382-3(a)(1). The amendment was made to address a lawsuit filed by a stockholder challenging the plan's definition of "Beneficial Ownership." The company believes the lawsuit's allegations are without merit but agreed to the amendment and a mootness fee of $250,000 to avoid litigation costs. The amendment specifically refines how various agreements, arrangements, understandings, and derivative transactions are considered in determining beneficial ownership, particularly in relation to Section 382 of the Internal Revenue Code.