Health stocks slumped on Friday as Wall Street weighed the impact that prominent vaccine skeptic Robert F. Kennedy Jr. could have on the industry after President-elect Donald Trump nominated him to lead the nation’s health and medical research agencies.

Kennedy has been criticized for making false medical claims. He has also vowed to purge the U.S. Food and Drug Administration.

President-elect Donald Trump said he’s tapping Robert F. Kennedy Jr. to run the Department of Health and Human Services, a move that would elevate a prominent vaccine skeptic and pharmaceutical industry critic to a top role on federal health policy.