What Personalis, Inc. told the SEC could break it.

Personalis derives a significant portion of revenue from a handful of customers: Moderna was 22% of 2025 revenue (genomic testing for its personalized-cancer-therapy trials) and the VA Million Veteran Program 17% (population sequencing), while Natera fell to 8% from 30% as that MRD-analysis project wound down — driving an overall 18% revenue decline to $69.6M; its top five customers represent the bulk of revenue, so loss, reduced orders or funding cuts at Moderna, the VA MVP or another large customer would materially hurt results.

“Moderna accounted for 22% and 28% and the VA MVP accounted for 17% and 9% of our revenue for the years ended December 31, 2025 and 2024, respectively.”

Personalis relies on a limited number of suppliers — and in some cases a sole supplier — for the instruments and materials used in its CLIA/CAP lab, most critically Illumina as the sole supplier of sequencers and associated reagents and the sole provider of maintenance and repair services for those sequencers; an Illumina supply interruption, price increase or inability to transition to an alternative platform (including if the FDA required marketing authorization for Illumina's research-use-only products) could disrupt its testing services.

“we rely on Illumina as the sole supplier of sequencers and various associated reagents, and as the sole provider of maintenance and repair services for these sequencers.”

Personalis is not yet profitable and saw 2025 revenue decline 18% to $69.6M; it funds its cash burn substantially through dilutive At-The-Market equity issuance, ending 2025 with ~$240.0 million of cash, cash equivalents and short-term investments that included ~$109.0 million of net ATM proceeds raised at a weighted-average $8.43 per share (plus a further $21.0M ATM raise in January 2026), so continued operations depend on capital-markets access and successful commercialization, creating dilution and funding risk.

“Ended the year with approximately $240.0 million in cash, cash equivalents, and short-term investments. This includes approximately $109.0 million in net proceeds from our At-The-Market (ATM) sales program, executed at a weighted-average price of $8.43 per share”

Personalis's diagnostics business depends on evolving regulation: FDA could require marketing authorization for laboratory-developed tests or for the research-use-only (RUO) products (e.g., Illumina's) it uses, adoption depends on Medicare and private-insurance reimbursement and clinical evidence, EU placement requires compliance with the costly In Vitro Diagnostic Regulation (IVDR), and it is subject to federal/state fraud-and-abuse laws and CLIA/CAP and state lab licensure; international trade policies including tariffs and sanctions could also affect its supplies.

“We currently use Illumina and other RUO products for our clinical diagnostic tests. If the FDA were to require marketing authorization for the sale of Illumina's RUO products and if Illumina does not obtain such marketing authorization, we would have to find an alternative sequencing platform for some or all of our test services.”