(Reuters) -Billionaire Ken Griffin's hedge fund Citadel has taken a short position in British drugmaker GSK , the Financial Times reported on Friday.

Citadel has taken a short position worth 305 million pounds ($384.5 million) in GSK stock, representing a 0.51% stake, according to data from the Financial Conduct Authority, the FT report said.

Citadel did not immediately respond to a Reuters request for comment. GSK declined comment, saying, "It is our consistent position that we do not comment on individual shareholders."

A short position represents a bet that a company's stock will fall in value. In a short sale, an investor sells borrowed stock on the bet that the shares will decline, allowing the investor to buy them back at a lower price and pocket the difference.

GSK announced a 2-billion-pound share buyback last week when it reported fourth-quarter results and lifted its long-term sales target to nearly $50 billion.

In 2024, GSK lost 7.5% of its value, underperforming rival AstraZeneca, which was down only 1.3%.

($1 = 0.7933 pounds)