On Friday, shares of Novavax leaped as much as 13.3%.
It comes after Novavax finalized a deal with the UK to supply 60 million doses of its potential coronavirus vaccine.
The biotech company didn't reveal how much the UK paid for the doses.
According to a press release the UK government will collaborate with Novavax on phase 3 trials of its NVX-CoV2373 vaccine.