The FBI is reportedly investigating Phil Mickelson in relation to possible insider trading. Two other individuals, billionaire investor Carl Icahn and Las Vegas gambler William Walters, are also reported to be the focus of the federal investigation.

The Federal Bureau of Investigation is reportedly investigating if Mickelson and Walters may have conducted illegal trades based on insider knowledge provided by Icahn. The specific trades in question relate to investments Mickelson and Walters made in Clorox, a company which makes cleaning products. Icahn’s company made a takeover attempt in 2011, pushing the share price of Clorox higher. During this period Mickelson and Walters both made profitable investments in Clorox. The timing of the investments raised suspicions that the pair might have been engaged in insider trading – generally defined as the use of knowledge not publicly available to gain an advantage in stock market trading.

It is unclear at the moment if, by informing Mickelson and Walters of plans of a takeover, Icahn would have been guilty of insider trading.

Mickelson’s lawyer has denied the golfer is a target of the investigators. The New York Times reports that FBI officials spoke with Mickelson roughly one year ago in relation to his investments.