Health care stocks were mixed pre-bell Thursday, with The Health Care Select Sector SPDR Fund (XLV) marginally higher and the iShares Biotechnology ETF (IBB) down 0.1%.

Keros Therapeutics (KROS) shares were down 73% after the company said it voluntarily halted dosing in the 3 mg/kg and 4.5 mg/kg treatment arms of its phase 2 TROPOS trial of cibotercept in combination with background therapy in patients with pulmonary arterial hypertension.

Corcept Therapeutics (CORT) stock was 6% lower after the company said a phase 2 trial assessing two doses -- 150 milligrams and 300 milligrams -- of dazucorilant in people with amyotrophic lateral sclerosis did not meet its primary endpoint.

Centene (CNC) shares advanced over 2% after the company said it continues to expect fiscal 2024 adjusted earnings of more than $6.80 per share and estimated fiscal 2025 adjusted earnings of at least $7.25 per diluted share. Both projections exceed analyst expectations.