Material Event Form 8 K

Item 8.01 Other Events.

On December 27, 2024, Personalis, Inc. (the "Company") entered into an Amended and Restated At-the-MarketSales Agreement (the "Amended Sales Agreement") with Piper Sandler & Co. ("Piper") and BTIG, LLC ("BTIG"). The Amended Sales Agreement amends and restates the At-the-MarketSales Agreement with BTIG, previously entered into on December 30, 2021, as amended by Amendment No. 1 to the At-the-MarketSales Agreement, dated December 21, 2023, to add Piper as a sales agent (Piper and BTIG, together, the "Sales Agents"), among certain other changes.

Pursuant to the Amended Sales Agreement, the Company may offer and sell shares of the Company's common stock ("Shares") from time to time through the Sales Agents.

The foregoing description of the Amended Sales Agreement is not complete and is qualified in its entirety by reference to the full text of the Amended Sales Agreement, a copy of which is filed herewith as Exhibit 1.1 to this Current Report on Form 8-Kand is incorporated herein by reference.

On December 27, 2024, the Company filed a prospectus supplement to the prospectus included in the Company's shelf registration statement on Form S-3(Registration No. 333-276204)(the "Registration Statement"), relating to an offering of Shares pursuant to the Amended Sales Agreement. The opinion of Cooley LLP relating to the Shares offered by the foregoing prospectus supplement is filed herewith as Exhibit 5.1 to this Current Report on Form 8-K.

The offering of the Company's common stock pursuant to the sales agreement prospectus, dated January 9, 2024, included in the Registration Statement is hereby terminated such that no further offers or sales will be made pursuant to such sales agreement prospectus.