Health care stocks were advancing premarket Monday, with the Health Care Select Sector SPDR Fund (XLV) up 0.4% and the iShares Biotechnology ETF (IBB) 0.8% higher.

Novo Nordisk (NVO) stock was down more than 10% after the company said its weight-loss drug semaglutide failed to meet its primary endpoint of reducing Alzheimer's progression in two phase 3 trials enrolling a total of 3,808 adults.

Merck (MRK) said late Friday that shareholders should not participate in the unsolicited mini-tender offer launched by Tutanota at $65 per share, which is well below recent market prices. Merck stock was up nearly 3% premarket.

Biogen (BIIB) shares were nearly 2% higher after the company and Dayra Therapeutics said they have entered a collaboration to research and develop oral macrocyclic peptides for priority targets in immunological conditions.