Management Change/Compensation (Form 8-K)

On September 14, 2026, David Horn resigned as the President, Chief Financial Officer and Treasurer of Seer, Inc. (the "Company") to pursue other interests, effective as of October 1, 2026. Mr. Horn's resignation is not the result of any disagreement with the Company related to its operations. The Company thanks Mr. Horn for his dedication over many years of service to the Company.

The Company has offered to extend the post-termination exercise period of all of Mr. Horn's options to purchase shares of the Company's Class A common stock, to the extent vested and exercisable at the time of his resignation's effectiveness, until one year following Mr. Horn's last day of service to the Company, subject to earlier expiration or termination in accordance with the applicable Company equity plan, and subject to Mr. Horn executing and not revoking a separation and release agreement with the Company.

In connection with Mr. Horn's resignation, on September 17, 2026, the Board appointed Omid Farokhzad, M.D. to the office of President of the Company, in addition to his current positions as Chief Executive Officer and Chair of the Board, and Charles Endweiss, Vice President, Financial Planning & Analysis of the Company as Treasurer of the Company, each effective as of October 1, 2026. Mr. Endweiss will also serve as the principal financial officer and principal accounting officer of the Company as such terms are used for purposes of the rules and regulations of the Securities and Exchange Commission.

Charles Endweiss, age 49, has served as the Company's Vice President, Financial Planning & Analysis since January 2021. Prior to joining the Company, Mr. Endweiss served as Head of Business Operations, Oral Health at Carbon, a provider of end-to-end digital 3D printing and manufacturing platform, from August 2017 to January 2021. Earlier in his career, Mr. Endweiss held a range of accounting, finance, and business operations positions at various technology companies. He holds a B.A. in Business from the University of Illinois, Urbana-Champaign and an M.B.A. from Santa Clara University.

Mr. Endweiss entered into an indemnification agreement on the Company's standard form, a copy of which was filed as Exhibit 10.1 to the Company's registration statement on Form S-1 (File No. 333-250035) on November 12, 2020.

Dr. Farokhzad and Mr. Endweiss are each continuing under the terms of their existing compensation arrangements with the Company. There are no arrangements or understandings between Mr. Endweiss and any other persons in connection with Mr. Endweiss' appointment as the principal financial officer and principal accounting officer. Mr. Endweiss does not have any family relationships with any directors or officers of the Company. Mr. Endweiss is not a party to any transaction, or series of transactions, required to be disclosed pursuant to Item 404(a) of Regulation S-K.