Novavax’s Covid vaccine got its green light — and the stock is tumbling. Here’s why.

Novavax Inc. can finally celebrate after earning a long-awaited green light for its Covid-19 vaccine. But that excitement is not reflected in its stock price. The Gaithersburg vaccine maker saw its share price plummet more than 28% Thursday, an unexpected reaction after the Food and Drug Administration granted the company’s product emergency use authorization for primary immunization in adults.