Cassava Sciences Inc.’s stock tumbled 85% Monday to put it on track for its biggest-ever one-day decline, after the clinical-stage biotech company said a trial of a treatment for mild to moderate Alzheimer’s disease failed to meet its main goals.

Cassava Sciences stock collapsed after an Alzheimer’s drug the company was testing failed to significantly help participants in a clinical trial. The stock plummeted 84% to $4.15 Monday after reporting that a Phase 3 trial meant to demonstrate the efficacy of a medication called Simufilam fell short of key milestones.

KEY TAKEAWAYS Cassava Sciences shares are plunging in premarket trading and are losing most of their value after the biotech firm said its experimental Simufilam drug aimed at treating Alzheimer’s disease failed a late-stage study.

Cassava Sciences Inc. ($SAVA) saw its stock plummet over 80% pre-market on Monday following the failure of a pivotal Phase 3 trial for its Alzheimer’s disease drug, simufilam. Trading was briefly halted earlier as the company revealed that the trial did not meet its primary endpoints for improving cognitive or functional decline at week 52,