Novavax boosted vaccine stocks in morning trading. Novavax rose 22%; Moderna and BioNTech SE rose 5%; UnitedHealth rose 4%; Humana rose 2%; Gilead Sciences and Novo Nordisk rose 1%.

The U.S. Food and Drug Administration approved Novavax's COVID-19 vaccine, but limited its use to older adults and people over the age of 12 with conditions that put them at risk due to the illness.

The vaccine's prospects were thrown into doubt after the FDA missed its April 1 target to approve the shot, which is a more traditional protein-based vaccine unlike its messenger RNA-based rivals. U.S. Health and Human Services Secretary Robert F. Kennedy Jr., a long-time vaccine skeptic, also raised concerns about the efficacy of the shot in a CBS interview.

Novavax Chief Corporate Affairs and Advocacy Officer Silvia Taylor said in an interview that the company had been notified of its approval late on Friday night after substantial back-and-forth with regulators.

Gold prices climbed on Monday as a softer dollar and renewed trade tensions, following U.S. Treasury Secretary Scott Bessent's reaffirmation of President Donald Trump's tariff threats, fuelled safe-haven demand.

Gold stocks and long VIX ETFs jumped in morning trading.

Moody's cut America's top sovereign credit rating by one notch on Friday, the last of the major ratings agencies to downgrade the country, citing concerns about the nation's growing debt pile.

Trump will impose tariffs at the rate he threatened last month on trade partners that do not negotiate in "good faith" on deals, Treasury Secretary Scott Bessent said in television interviews on Sunday.