Federal investigators have launched an insider-trading inquiry into the world of finance, gambling and sports, investigating a group of high-profile investors that includes Phil Mickelson, Carl Icahn and a Las Vegas bettor named Billy Walters.
The Federal Bureau of Investigation and the Securities and Exchange Commission are examining whether Mr. Mickelson and Mr. Walters traded illicitly on nonpublic information from Mr. Icahn about his investments in public companies, people briefed on the probe said.
The FBI and SEC are examining whether Mr. Walters on at least one occasion passed a tip on to Mr. Mickelson, these people said, and are studying the two men’s trading patterns.
Mickelson’s lawyer says his client is not the target of any investigation.
The three-time Masters winner was approached by two FBI agents after finishing his first round at the Memorial Tournament in Ohio to speak with him about the investigation.
Mr. Walters, born in Kentucky to a family of professional poker players, is a legendary sports bettor who wagers based on computerized forecasts of the outcomes of games, among other factors. He has also become a force in the Las Vegas real-estate world and has bought and sold golf courses.
Mr. Walters and Mr. Mickelson, 43, play golf together, said people familiar with their relationship. Sometimes Mr. Walters has suggested stocks for Mr. Mickelson to consider buying, one of the people said.
Mr. Icahn said he doesn’t know who Mickelson is, which is another story in and of itself.