The former soccer star entered into a promotional agreement with the gym franchise that is co-owned by the actor, but things quickly soured.

The former English soccer star David Beckham is entangled in a court battle against F45, a popular global fitness brand co-owned by the actor and entrepreneur Mark Wahlberg.

Mr. Beckham claims that F45 failed to live up to its contractual agreement after he signed a promotional deal to help grow the brand in 2020 before its initial public offering. “F45 substantially benefited from its relationship with Beckham, who enhanced F45’s public profile and credibility,” Mr. Beckham’s lawyers said in court documents, adding that the company went public in 2021 with a valuation nearly three times higher than it had two years earlier.

Now, Mr. Beckham claims that F45 failed to issue the “substantial cash and equity compensation” that was outlined in their original agreement. He says that when the business began to falter in 2022, because of fiscal mismanagement and macroeconomic pressures, F45 withheld millions of dollars it was supposed to pay him.

Here is what we know about the case so far.

What is the crux of the lawsuit?

F45 entered into a promotional agreement with Mr. Beckham through his company DB Ventures Limited in 2020, according to court documents. In the years that followed, Mr. Beckham claims, F45 failed to follow through on at least two promises: transfer nearly one million shares of stock in a timely manner, and issue $5 million worth of additional shares. He said the delay in transferring the initial shares cost him $9.3 million, as the stock price dipped.

Mr. Beckham filed a suit in May 2023 claiming he’s entitled to an excess of $14 million in damages from F45, not including interest.

What is F45?

F45 is a fitness franchise that started in Australia in 2013. The company offers 45-minute, bootcamp-style workouts guided by in-studio trainers and electronic displays through its network of franchisee workout studios. There are more than 2,000 studios in over 50 countries, according to its website.

What is Mr. Wahlberg’s connection to F45?

In 2019, Mr. Wahlberg acquired a 36 percent stake in the business through his investment group, according to the lawsuit. He is also a board member of F45.

He regularly appears in a promotional capacity for the company, including in an Instagram video on the gym’s account as recently as this week.

What have Mr. Beckham and Mr. Wahlberg said about the lawsuit?

Representatives for both parties have not responded to requests for comment regarding the lawsuit as of Tuesday. However, lawyers for F45 have responded to Mr. Beckham’s complaint in court documents, denying multiple allegations. F45 also claims that Mr. Beckham has not fully performed his obligations and that he is “attempting to benefit from his own wrongdoing and has unclean hands.”

Has F45 been sued by other notable people?

Yes. In 2017, the former N.F.L. wide receiver Terrell Owens sued F45 for failing to pay him more than $700,000 in a faltered agreement. Mr. Owens was paid $15,000 for creating a short promotional video, according to numerous outlets, but he claimed F45 was supposed to pay him a $25,000 bonus for each of the first 25 F45 gyms that opened across the United States, and then $5,000 for new gyms after that.

A spokesman for the company told TMZ that Mr. Owen’s complaint was a “total fabrication” and that he “picked a fight with the wrong company.” It is unclear how that case came to a close.