Healthcare stocks were mixed premarket Thursday, with the State Street Health Care Select Sector SPDR ETF (XLV) retreating by 0.2% and the iShares Biotechnology ETF (IBB) advancing 0.1%.

Bio-Techne (TECH) stock rose more than 20% premarket after the company signed a definitive agreement to be acquired by Germany's Merck KGaA for $73 a share, representing an enterprise value of $11.3 billion.

RadNet's (RDNT) shares were down 1.8% pre-bell after rising 3.5% at the prior close. The company's DeepHealth unit said it received FDA 510(k) clearance for two breast imaging AI tools, including a breast arterial calcification assessment and prior exam integration for its ProFound Pro platform.

Taysha Gene Therapies (TSHA) stock lost more than 9% after the company priced an underwritten public offering of 32.5 million shares at $6.00 each and pre-funded warrants to purchase 833,333 shares at $5.999 each.