09:01 AM EST, 11/13/2025 (MT Newswires) -- Health care stocks were mixed premarket Thursday with the Health Care Select Sector SPDR Fund (XLV) slightly advancing and the Shares Biotechnology ETF (IBB) marginally lower.

Day One Biopharmaceuticals ( DAWN ) shares were down 20% after the company said it has agreed to acquire Mersana Therapeutics ( MRSN ) in a transaction valued at up to about $285 million. Mersana Therapeutics ( MRSN ) stock was up more than 208% pre-bell.