Mersana soars on Day One's $285 mln buyout deal

Shares of drug developer Mersana Therapeutics MRSN.O more than triple to $26.91 premarket, its highest in nine months

MRSN says Day One Biopharmaceuticals DAWN.O agrees to acquire Mersana Therapeutics in a deal that could be worth up to $285 million

Under the agreement, Day One will pay Mersana shareholders $25/shr in cash upfront - MRSN

Investors can receive up to an additional $30.25/ shr if certain milestones are met, bringing the total possible payout to $55.25/shr - MRSN

Co says deal is expected to close by the end of January 2026

MRSN develops experimental cancer drugs; Day One focuses on developing drugs for pediatric and adult cancer patients - MRSN

Including session's move, stock down ~24% YTD