 Shares of Atai Life Sciences NV ATAI, -2.59 tumbled about 44 in premarket trading on Friday after the company said a Phase 2a clinical trial evaluating a ketamine therapy for treatment-resistant depression did not meet the primary endpoint. Atais stock has declined 60.1 over the past year, while the SP 500 SPX, -1.16 is down 19.0. 