Last Updated May 31, 2014 7:30 AM EDT
The U.S. Federal Bureau of Investigation and the Securities and Exchange Commission are investigating possible insider trading involving investor Carl Icahn and golfer Phil Mickelson, according to reports in The New York Times and the Wall Street Journal.
According to the Times, the probe also includes well-known Las Vegas gambler William T. Walters. People briefed on the investigation told the Times that authorities are questioning what role Icahn may have had in sharing information about one of the stocks: Clorox.
The Wall Street Journal characterizes the investigation as " a major insider-trading probe."
Sources told the Journal they're investigating whether over the past three years Icahn may have given tips to Walters, who on at least one occasion may have passed on information to Mickelson.
"We do not know of any investigation," Icahn told the Journal on Friday. "We are always very careful to observe all legal requirements in all of our activities."
Icahn was profiled by "60 Minutes" in 2008.
A lawyer for Mickelson denied to the Journal that the golfer was involved.
"Phil is not the target of any investigation. Period," said the lawyer, Glenn Cohen.
Sources say FBI approached Mickelson Thursday as he competed in the Memorial tournament in Dublin, Ohio. His sports related websites and twitter accounts were silent on the allegations.
Mickelson has won 42 events on the PGA Tour, including five major championships: three Masters titles (2004, 2006, 2010), a PGA Championship (2005), and an Open Championship (2013). Mickelson is one of 15 golfers in the history of the sport to win at least three of the four professional majors.