Why Is PSNL Stock Up 5% After-Hours?

• Merck has a long-standing relationship with Personalis through collaborations on individualized therapies.
• According to the report, Merck has expressed interest in Personalis, along with two other suitors. 
• Stocktwits could not immediately verify the report.

Shares of Personalis (PSNL) rose 5% after-hours on Thursday following rumors that the precision oncology company is exploring strategic options, including a potential sale, after receiving takeover interest from Merck & Co. (MRK) and at least two other parties.

Personalis has hired investment banks Centerview and TD Securities, along with law firm Cooley, to review its options, according to a report in Street Insider.

Stocktwits could not independently verify the news. Personalis and Merck did not immediately respond to a request for comment.

What Does PSNL Do?

Personalis develops advanced genomic tests and analytics, with a focus on its NeXT platform for comprehensive tumor profiling, minimal residual disease (MRD) monitoring, and supporting the development of personalized cancer vaccines and immunotherapies.

Merck has a long-standing relationship with the company through collaborations on individualized therapies. In Personalis’s full-year 2025 financial results, the Merck relationship contributed $4.9 million in revenue — more than double the $2.0 million recorded in 2024. Merck also invested $50 million in Personalis through a private placement in late 2024.

Personalis is based in Fremont, California. The company remains unprofitable, with trailing 12-month revenue of around $64.5 million and a net loss of about $95.5 million.

Merck, meanwhile, is best known for its cancer drug Keytruda. The company is currently attempting to diversify its pipeline as the drug nears core U.S. patent expirations in late 2028. The company, in recent months, acquired Verona Pharma for about $10 billion, Cidara Therapeutics for about $9.2 billion, and Terns Pharmaceuticals for almost $6.7 billion. The acquisitions are aimed at adding more growth drivers to its pipeline and reducing its reliance on Keytruda.

How Did PSNL Retail Traders React?

On Stocktwits, retail sentiment around PSNL stock stayed within the ‘extremely bullish’ territory over the past 24 hours, while message volume stayed at ‘extremely high’ levels.

A Stocktwits user wondered at the company’s other potential suitors. “Good for us stockholdders,” they said.

Another wondered why the stock isn't edging up higher on buyout talks.

A third user expressed doubts about Merck acquiring the company for a discount.

PSNL stock has nearly doubled year-to-date. 

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