US golfer Phil Mickelson's bets topped $1 billion, says former gambling associate

Phil Mickelson has placed bets worth a total of more than $1 billion during his career, including a $400 000 wager on the outcome of the 2012 Ryder Cup, according to excerpts from a forthcoming book published in US media on Thursday.

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The revelations about Mickelson's betting are contained in "Gambler: Secrets from a Life at Risk" by professional US gambler Billy Walters, a former close associate of the six-time major winner.

In an extended excerpt from the book published by the FirePit Collective website on Thursday, Walters detailed frenzied betting by Mickelson over the past three decades.

A biography of Mickelson published in 2022 by US golf writer Alan Shipnuck reported that the golfer had racked up more than $40 million in gambling losses throughout his career.

Mickelson last year acknowledged he had struggled with gambling in the past, describing his betting as "reckless and embarrassing" and revealing that he had undergone "hundreds of hours of therapy" to address the issue.

However, Walters said the scale of Mickelson's losses had been significantly under-reported, and estimated the golfer had in fact made bets worth more than $1 billion in total.

"Based on our relationship and what I've since learned from others, Phil's gambling losses approached not $40 million as has been previously reported, but much closer to $100 million," Walters wrote.

"In all, he wagered a total of more than $1 billion during the past three decades."

Walters and Mickelson's relationship ruptured when Walters was investigated and subsequently convicted and jailed over an insider trading scam.

Mickelson wasn't charged but repaid almost $1 million from money made in the deal.

Walters