Roche’s seeming lack of confidence in the future of AT-527 appears to be weighing on investors. Atea shares, which soared above $88 in February 2021, dropped 20% to below $9 apiece in early trading Wednesday.

Even if the drug succeeds in the next phase of research, AT-527 will likely lag pills developed by Merck and Pfizer that have both shown dramatic benefit in late-stage trials. Merck and its partner, Ridgeback Biotherapeutics, have already won approval to sell their drug in the U.K.

Still, Atea does have a path ahead, Roanna Ruiz, an analyst at SVB Leerink, wrote in a note to investors. There may well be room for multiple drugs to treat COVID-19 in the future, especially if doctors start to use combinations of medicines to fight the novel coronavirus. There’s precedent for such “cocktail” therapies in HIV, among other conditions.

Atea stockholders would be reassured by a quick move to secure another major pharmaceutical partner, Ruiz said. The company should also give investors more details on how it plans to amend the pivotal trial called MORNINGSKY and exactly how it will spend its money going forward, she said. As of Sept. 30, Atea had $840 million in cash and cash equivalents.

Last year, Atea looked like one of the biotech industry’s biggest success stories. The company had one of the top initial public offerings of 2020, days after securing the Roche deal. Initial results from the collaboration also looked promising, with a study released in June 2021 that showed AT-527 could help curb viral loads in patients hospitalized with COVID-19.

The results in October were from a study called MOONSONG that included patients with mild or moderate COVID-19. At the time, Atea said the negative findings could be explained by the mostly young and healthy participants included in the study. So, it’s switching the focus for the pivotal MORNINGSKY trial. The company plans to announce data from that study in the second half of 2022.