The FBI and securities regulators are investigating activist investor Carl Icahn, golfer Phil Mickelson and gambler Billy Walters as part of a long-running insider trading probe, the Wall Street Journal and New York Times reported on Friday.

The Journal said authorities were investigating whether Icahn passed tips on investments he was planning to make to Walters, and whether Walters had tipped Mickelson on at least one occasion.

The probe began with trading in shares of Clorox, the Journal reported.

Icahn told the Journal he had done nothing wrong, as did a lawyer for Mickelson. Walters declined comment to the paper.

Icahn told CNBC that he's never given out inside information.

"We've never heard from the FBI," Icahn said Friday evening. "We don't know of any investigation." The billionaire investor also noted that he's never met Mickelson, although he does know Walters from Las Vegas.

Separately, the Times reported that investigators are also looking into trading around shares of Dean Foods, a strand of the probe that does not include Icahn.



For the full WSJ story, click here. For the Times story, click here.

Scott Wapner contributed reporting for this article.