Why Are Atea Pharmaceuticals Shares Plunging Today?

Atea Pharmaceuticals Inc AVIR has reported data from the Phase 2 MOONSONG trial of AT-527 in the outpatient setting in patients with mild or moderate COVID-19.
Related: Atea Unveils Trial Amendments, New Data For COVID-19 Program.
The trial did not meet the primary endpoint of clear reduction in SARS-CoV-2 viral load in the overall population compared to placebo.
Approximately two-thirds of patients were low-risk with mild symptoms.
However, in high-risk patients with underlying health conditions, a reduction of viral load of about 0.5 log10 at Day 7 was observed at 550 mg and 1,100 mg BID compared with placebo.
Based on AT-527 data and the evolving COVID-19 environment, Atea and its partner Roche Holdings AG RHHBY are assessing potential modifications to the Phase 3 MORNINGSKY trial.
Hence, the companies now anticipate Phase 3 MORNINGSKY data in the 2H of 2022 against 2H of 2021 expected earlier.
Atea will host a conference call today at 8:30 a.m. ET.
Price Action: AVIR shares plunged 70.10% higher at $12.10 premarket on the last check Tuesday.