With all the attention on Rory McIlroy to compartmentalize - at least until Friday - Phil Mickelson potentially has an equally damaging personal situation brewing.

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The Wall Street Journal is reporting that federal investigators are looking into the business dealings of Mickelson, investor Carl Icahn and Las Vegas gambler William "Billy" Walters in a potential major insider-trading probe.

According to the report, the FBI and Securities and Exchange Commission are investigating whether Walters and Mickelson traded illicitly on nonpublic information that Icahn provided about his investments in public companies, sources with knowledge of the probe told the WSJ.

The investigation involves a three-year period in which Icahn divulged information to Walters about "potentially market-moving investments by Mr. Icahn's company," the WSJ reported. The FBI and SEC also are gathering information on whether Walters passed on a tip to Mickelson. The trading patterns of the two are being studied.

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"Phil is not the target of any investigation. Period," said a lawyer for Mickelson, Glenn Cohen, on Friday, adding that an FBI agent had told him Mr. Mickelson wasn't a target. The FBI declined to comment on Mr. Cohen's statement.

"We do not know of any investigation," Icahn told the Wall Street Journal on Friday. "We are always very careful to observe all legal requirements in all of our activities." The suggestion that he was involved in improper trading, he said, was "inflammatory and speculative."

Reuters reported that the investigation centers on suspicious trades in Clorox Co options days before Icahn announced a bid to acquire the company in 2011, according to the Journal, citing people briefed on the probe.

Icahn acquired a 9.1 percent stake in Clorox in February 2011. In July, he offered to buy the company, a move that valued it at above $10 billion and sent its stock soaring.

Investigators expanded their probe to look at trading patterns by Walters and Mickelson relation to Dean Foods, Co. Icahn denied trading in Dean Foods.

Two FBI agents asked Mickelson to speak with them after his opening-round 72 on Thursday at the Memorial, but he referred them to Cohen, the WSJ reported. No indication yet exists that the government will bring a case to court in the current investigation.

Mickelson shot a 2-under 70 Friday and is 10 strokes behind leader Paul Casey at 2 under for the event. Mickelson is one stroke behind first-round leader McIlroy, who followed a 9-under 63 with a 6-over 78 Friday.

Do you think the investigation will have an effect on Phil Mickelson's play this weekend? Comment below or tell us @SportsWN.