Mayweather, whose fights generate the biggest pay-per-view numbers in the sport, has worked with Golden Boy on a fight-by-fight basis for all of his nine bouts since his 2007 blockbuster against De La Hoya, which set the all-time pay-per-view buy record at nearly 2.5 million subscriptions.
But Mayweather, whose own company, Mayweather Promotions, co-promoted his fights, only worked with Golden Boy because of Schaefer, with whom he has grown close over the years. Mayweather and De La Hoya do not like each other and have never hidden that fact.
So when Mayweather, the junior middleweight and welterweight champion, returns for his next fight on Sept. 13, Golden Boy will no longer be involved, Mayweather Promotions chief executive Leonard Ellerbe told ESPN.com Monday night.
When asked if Mayweather would work with Golden Boy again without Schaefer, Ellerbe said, "Absolutely not."
That is a big hit worth millions of dollars to De La Hoya's company.
"We have a great working relationship with Richard Schaefer and that will never change," Ellerbe said. "Richard is a good friend and a great businessman and an excellent promoter. Richard will have an impact in anything that he decides to do, a tremendous impact. He built that company from the ground up and did a phenomenal job. We've had a very close relationship for a number of years and worked hand-in-hand on a number of great fights.
"Mayweather Promotions will continue to promote Floyd's fights and Floyd will continue to put on the biggest fights in boxing. I have a tremendous team and staff and we continue to expand year by year and we're ready to go."
Golden Boy Promotions had no comment.
Schaefer, the former Swiss banker who co-founded Golden Boy Promotions with close friend De La Hoya in 2002, has served as its only CEO. His exit from the company was not unexpected, given the public issues between Schaefer and De La Hoya over the past few months, but the timing was a bit surprising -- a few days before De La Hoya's induction on Sunday into the International Boxing Hall of Fame.
"After more than 10 years with Golden Boy, it is time to move on to the next chapter of my career," Schaefer said in a statement earlier Monday. "This decision has required a great deal of personal reflection, but ultimately I concluded that I have no choice but to leave. I have succeeded in banking and I have succeeded in boxing, and I look forward to the next opportunity.
"I am proud to remain a shareholder, so I have a strong interest in the continued success of the company. I am proud of what we have accomplished at Golden Boy, but I now look forward to new challenges."
Under Schaefer's guidance, Golden Boy became a powerhouse. Schaefer was the point person in multiple record-breaking promotions, developed close relationships with HBO and later Showtime, closed an output deal for a boxing television series on Fox Sports 1, worked with numerous mainstream sponsors and made a deal to serve as the exclusive promoter of fights at the Barclays Center in Brooklyn, New York, while also maintaining a close relationship with the MGM Grand in Las Vegas.
Schaefer has promoted the two biggest-selling pay-per-view events in boxing history, the 2007 showdown between Mayweather and De La Hoya, which generated a record of nearly 2.5 million buys, and the 2013 fight between Mayweather and Canelo Alvarez, which set the all-time pay-per-view revenue record ($150 million), all-time gate record ($20 million) and sold the second-most units (2.2 million).
There has been wide speculation that Schaefer will eventually join Mayweather Promotions or found his own company and continue to work closely with Mayweather and his adviser, Al Haymon, who has a deep stable of fighters besides Mayweather.
Ellerbe did not want to address that.
"Richard just put in the resignation (Monday) and I'm not going to speak on what Richard might do next," Ellerbe said. "That is for Richard to say. But Richard will have a tremendous impact on whatever he decides to do and wherever he goes. We always welcome smart leaders, but I don't know what his future is."
Ellerbe said that while Golden Boy co-promoted Mayweather's fights, it was arranged that way only because of Schaefer and his right-hand man, chief operating officer and chief marketing officer Bruce Binkow, who many expect will be leaving Golden Boy shortly in order to join Schaefer in his next endeavor.
"I've been in a hundred strategy sessions, I've been in a hundred meetings, I've been in a hundred planning sessions on our events and the people I've worked closely with are Richard and Bruce," Ellerbe said. "I've never seen Oscar in one of those sessions, not once. We've never had one discussion about business. But I wish (Golden Boy) nothing but the best."
Mayweather's September opponent has not been determined. Ellerbe said Mayweather is on vacation following his May 3 victory against Marcos Maidana, and when he returns "we'll figure it out. We don't know who we're fighting yet or where we're fighting."
A few days before Mayweather outpointed Maidana to unify 147-pound titles, he was asked about the disintegrating Schaefer-De La Hoya relationship and said he would always have a place for Schaefer at his company.
"We like working with Richard Schaefer. Richard Schaefer is Golden Boy," Mayweather said. "He does all the day-to-day leg work. He works hard. He's up late on the phone with Leonard, three, four in the morning, taking flights, and people that's putting work in like this you got to commend them.
"Richard always has a home over here. We would love to work with him hand-in-hand if he has any problems over there because we know it's a company Richard Schaefer built. We working hand-in-hand already. We would love to work with Richard. He's a great guy, a great father. Richard knows the door is always open. Richard Schaefer knows he's family."
Schaefer, also speaking a few days before Mayweather-Maidana, addressed his future and the possibility of working with Mayweather if he were to leave Golden Boy.
"Floyd and me are friends, we have a close relationship but truth be told, I haven't had any conversations with Floyd because I don't think that would be appropriate, because I have a job at Golden Boy and I'm gonna continue to do it," Schaefer said. "But once I do either stay or not stay, whatever the decision gonna be, then I will look at what opportunities are out there and, obviously, Floyd, whether I'm there or not there has a bright future.
"Al and me are friends. We work very well together. We have done good business together. He's a businessman I highly respect and regard. His accomplishments are not just in the sport of boxing. But I am not going to discuss my thoughts. I don't really think about what I'm gonna do next. I have a pretty good idea."