What happened

Shares of Novavax (NVAX 0.86%) were sinking 9.6% as of 11:47 a.m. ET on Monday. The company didn't announce any new developments. So what's behind the big decline?

Other vaccine stocks aren't falling nearly as much. Some were even up a little. That rules out the likelihood that declining concerns about the omicron variant played a major factor behind Novavax's drop.

Instead, investors are probably growing more anxious about Novavax's planned filing for U.S. Emergency Use Authorization (EUA) of it COVID-19 vaccine NVX-CoV2373. Some investors could also be worried about the quality of Novavax's submission to the Food and Drug Administration (FDA) even if it doesn't experience another delay with the filing.

CEO Stanley Erck's interview with Yahoo! Finance Live last Thursday likely didn't help reassure investors. When asked about when the FDA filing would be done, Erck replied, "It's probably going to be next week, but I'm sticking with the claim that we'll be doing this by the end of this year."

A healthcare professional giving a person a shot.

Image source: Getty Images.

So what

Yet another delay in a U.S. filing for NVX-CoV2373 wouldn't be catastrophic for Novavax as long as the company completes the submission soon in the new year. However, management's credibility would definitely take another big blow.

But it's premature at this point to speculate that Novavax won't complete the U.S. EUA filing this week. It's also useless to fret about the quality of the company's FDA package. Novavax recently won European Union authorization for NVX-CoV2373. That shows that the vaccine maker can successfully meet regulators' manufacturing-quality hurdles.

Now what

Investors don't like waiting, but that's exactly what they'll have to do for now with Novavax. The company could complete its EUA filing any day now. It could also pick up new authorizations in other countries where it awaits regulatory decisions.