The stock closed at $9.23 as the Nasdaq slipped 0.13% and the Dow fell 0.63%, while trading volume reached 9.2 million shares.
The decline ended a two-day winning streak and left Novavax 22.89% below its 52-week high of $11.97 set on 26 February.
Novavax underperformed peers including Johnson & Johnson, Pfizer and Merck, whose shares also fell but by smaller percentages during Thursday's broader market weakness.
Why did Novavax stock fall after its earnings report beat analyst expectations?
Can Novavax's strategy survive an activist investor's push for a board overhaul?