When the FTX cryptocurrency exchange imploded last fall, Tom Brady, the seven-time Super Bowl-winning quarterback, made an urgent call.

He called Sina Nader, FTX’s head of partnerships. Exchange staff were in the middle of a crisis meeting with beleaguered founder, Sam Bankman-Fried. Mr. Nader could not answer. “I never expected to turn down a call from Tom Brady,” he said.

Mr. Brady had reasons to be concerned. As an “ambassador” for FTX, he had appeared at the company’s conference in the Bahamas and on TV commercials that promoted the exchange as “the most trusted” institution in the loosely regulated world of crypto.

His money was also at stake. As part of a recommendation Under the deal Mr Brady signed in 2021, FTX had paid him $30 million, a deal made up almost entirely of FTX stock, three people with knowledge of the contract said. Mr. Brady’s then-wife, supermodel Gisele Bundchen, was paid $18 million in FTX stock, one of the people said.

Now FTX is bankrupt and Mr. Bankman-Fried is accused of fraud. Mr Brady, 45, and Ms Bündchen, 42, have been sued by a group of FTX clients seeking compensation from the celebrities who endorsed the exchange. In addition, under the terms of the deal, the former couple, who divorced last year, would be required to pay taxes on at least a portion of their now worthless FTX shares, two people familiar with the endorsement deal said.

Their situation is the high-profile example of a humiliating reckoning with which the actors, athletes and other celebrities rushed to embrace the easy money and online hype of cryptocurrencies. During the boom, Paris Hilton, Snoop Dogg, Reese Witherspoon and Matt Damon all flocked or invested in crypto projects, bringing a mainstream audience to the shaky world of digital currencies. It was fun – and lucrative – while prices skyrocketed.

But last year’s crash ended the celebrity crypto bonanza.

In October, the Securities and Exchange Commission ordered Kim Kardashian to pay $1.26 million for failing to make adequate disclosures when she approved the EthereumMax crypto token. In December, a California attorney sued two crypto companies, MoonPay and Yuga Labs, accusing them of using a “massive network of top musicians, athletes, and celebrity clients” to mislead investors about digital assets.

In March, the SEC charged actress Lindsay Lohan, online influencer Jake Paul, and musicians including Soulja Boy and Lil Yachty with illegally promoting crypto assets. And at the end of May, after months of failed attempts, a process server court papers delivered to Shaquille O’Neal, the retired basketball star, who was charged with promoting FTX, according to legal documents. Mr. O’Neal was served while broadcasting a National Basketball Association playoff game.

Representatives of Mr. Brady, Mr. Bankman-Fried and MoonPay declined to comment. A spokeswoman for Yuga Labs said the company had “never paid a celebrity to join the club.” Representatives for Ms. Bündchen and Mr. O’Neal did not respond to requests for comment.

Tech start-ups and celebrities have long had a symbiotic relationship. The start-ups offer stars a way to make money while staying on the cutting edge of internet culture; the celebrities help young companies gain credibility and reach a larger audience.

Of all the startups that recruited celebrities to endorse crypto, FTX was perhaps the most enthusiastic. While trying to make FTX a household name, Mr. Bankman-Fried made a list of celebrities he could imagine promoting the company, Mr. Nader, the former FTX executive, recalled. Mr. Brady’s name was at the top.

mr. Nader, a former college football player, was in charge of recruiting Mr. Brady and other stars. In June 2021, Mr. Brady and Mrs. Bündchen agreed to a deal with Mr. Bankman-Fried, praising the “revolutionary FTX team”. Mr. Brady seemed genuinely interested in crypto, Mr. Nader said, and had occasional conversations with Mr. Bankman-Fried.

“Imagine a tiger and a lion talking,” Mr. Nader said. “They’re slightly different, they do different things, but they’re really formidable in their own arenas.”

In 2021, Mr. Brady also co-founded Autograph, which helps famous people sell the crypto collectibles known as nonfungible tokens or NFTs. Autograph raised more than $200 million from investors and Mr. Bankman-Fried joined the board.

That same year, Mr. Brady and Mrs. Bündchen with star in a $20 million ad campaign for FTX, with commercials running during NFL games. Mr. Brady also posted TikTok Videos with Mr. Bankman-Fried from FTX’s headquarters in the Bahamas, where he spoke to hundreds at a conference. Backstage, Mr. Bankman-Fried remarked that he could envision buying a football team with Mr. Brady one day. Ms. Bündchen also appeared at the conference as FTX’s head of environmental and social initiatives.

When FTX collapsed last November, the company’s valuation plummeted from $32 billion — including Mr. Brady and Ms. Bündchen’s $48 million worth of shares — to zero. The pair had also received a small amount of Ethereum, Bitcoin and Solana tokens to trade on the platform, said one of the people who disappeared in FTX’s bankruptcy.

Mr. Brady has not publicly commented on FTX or his relationship with Mr. Bankman-Fried. After FTX’s crisis meeting in November, Mr. Nader called him back.

“He was worried,” Mr. Nader said. “The very first thing he asked me was, ‘Sina, how are you? I know you put your heart and soul into this.’”

said Mrs. Bündchen in March interview with Vanity Fair that she had “trusted the hype” and felt “blindsided.”

Mr. Brady’s other crypto venture has also struggled. Autograph revenues fell last year amid the crypto crisis, a person familiar with finance said. The startup has shifted its strategy to focus more on helping celebrities find ways to foster loyalty among their fans, and less on marketing crypto tokens to consumers, the person said. The company has also removed some crypto language from its marketing and downplayed terms like NFT, another person with knowledge of the company said.

Autograph also laid off more than 50 employees in rounds of layoffs, a third person said. The reductions were previously reported by Insider. An Autograph spokeswoman declined to comment.

Mr. Brady has also faced legal troubles. In December, Adam Moskowitz and the law firm of Boies Schiller Flexner filed a lawsuit in Florida federal court accusing him and Ms. Bündchen of misleading investors. Other defendants include comedian Larry David, NBA star Steph Curry and tennis player Naomi Osaka, all of whom supported FTX.

“None of these defendants conducted any due diligence prior to marketing these FTX products to the public,” the lawsuit said.

Some celebrities narrowly escaped the crypto mess. Katy Perry, the pop star, has had talks about a partnership with FTX that never materialized, three people familiar with the situation have said.

In the spring of last year, Taylor Swift discussed a deal with FTX that could have raised as much as $100 million, two people familiar with the matter said. A tour sponsorship was on the table after Ms Swift declined other promotional options, a person with knowledge of the talks said. The size of the deal was previously reported by The Financial times.

mr. Moskowitz, the lawyer suing the celebrities, said on a podcast in April that Ms. Swift had performed due diligence on FTX and asked the exchange to prove that her cryptocurrencies were not unregistered securities. His comments sparked a flurry of headlines about Ms. Swift’s business acumen. But in an interview with The New York Times, Mr. Moskowitz said he had no prior knowledge of the talks.

In reality, Ms. Swift’s side signed the sponsorship deal with FTX after more than six months of discussions, three people with knowledge of the deal said, and it was Mr. Bankman-Fried who backed out. The last-minute reversal left Ms. Swift’s team frustrated and disappointed, two of the people said.

A spokeswoman for Ms Swift declined to comment.