The Miami Dolphins are in advanced talks to sell a minority stake in the team to private equity firm Ares Management and billionaire Joe Tsai, CNBC has learned, highlighting the growing trend of owners looking to build their sports portfolios to include multiple teams and operate their own stadiums to maximize revenue.

The deal, which would also include Hard Rock Stadium, the operating rights for the Miami Grand Prix F1 race and about half of the Miami Open, values the assets at $8.1 billion, according to a person familiar with the negotiations.

A controlling valuation for the same assets would have been north of $10 billion, a source close to the negotiations told CNBC.

This would mark the first private equity investment for the NFL since the league approved the new finance rules in August.

CNBC has valued the Miami Dolphins as the league’s eighth most valuable team at $7.1 billion, which does not include the stadium.

As part of the negotiations, Ares Management would buy 10% of the team and Tsai, owner of the Brooklyn Nets, is in talks to buy another 3% stake, the person said. Bloomberg earlier reported the talks.

Nothing has been signed and there is no timeline for a potential deal, the person added.

The Miami Dolphins and the NFL declined to comment, and Tsai’s BSE Global did not immediately respond to a request for comment.

Businessman Stephen Ross purchased the Miami Dolphins in 2009 for $1.1 billion.

A source close to the Miami Dolphins owner said Ross plans to use the money from the sale to increase his portfolio of South Florida real estate and further his investment in sports.

Ross, also the CEO of Related Companies, is just one of a handful of team owners that also owns and operates the team’s stadium. This allows him to bring in revenue from events held at the stadium such as the Miami Grand Prix and Miami Open tennis tournament.

The Dolphins made $673 million in revenue in 2023.

Earlier this year, Ross reportedly turned down a record $10 billion offer for control of the team, Formula One Miami Grand Prix and Hard Rock Stadium. Ross said he wanted to keep the team within his family.

In late August, NFL owners voted in favor of allowing select private equity firms to invest up to a 10% stake in teams.

The NFL is the last of the major professional sports to allow PE investment, but the league softened its stance as rising valuations have made finding buyers increasingly difficult.

Ares, which manages $450 billion in assets, was one of the four groups that the NFL approved for investment in its teams.

Meanwhile, Tsai has been building a sports empire. The chairperson of the Alibaba Group currently owns the Brooklyn Nets, New York Liberty and operates the Barclays Center. He also owns the San Diego Seals and is co-owner of the Las Vegas Desert Dogs, both Premier Lacrosse teams, in addition to the Los Angeles FC of Major League Soccer.

The National Football League has informed owners and investment firms that it intends to take a percentage of private equity profits on any future sales of ownership stakes, according to people familiar with the matter.

NFL owners voted Tuesday to allow private equity firms to take a maximum 10% stake in teams.

The league has never allowed private equity investment before. Major League Baseball, the National Basketball Association and the National Hockey League already allow up to 30% of teams to be owned by investment firms, though the cap for individual funds is between 15% and 20%.

No other league takes a percentage of the so-called carry — the percentage of a fund’s investment profits that managers typically receive as compensation — for all private equity firms. It was unclear heading into the owners’ meeting if the NFL plan would apply to all or only some firms, or what percentage of the profits the league wanted to take.

The NFL has informally told investment firms that if they make a return on an investment, it wants a portion of the profits to be returned to the league.

“Each of us are privileged to own an asset that we’re custodians of the local community and we don’t want ownership that’s putting making money first,” New England Patriots owner Robert Kraft told CNBC’s “Squawk Box” on Wednesday. “If you do your job and you present a good product, the community gets behind it.”

It was unclear if the NFL’s plans to take a piece of profits would deter future investment from private equity. The initial approved firms include Ares Management, Sixth Street Partners and Arctos Partners, and a consortium of investors including Dynasty Equity, Blackstone, Carlyle Group, CVC Capital Partners and Ludis, a platform founded by investor and former NFL running back Curtis Martin.

The NFL declined to comment.

Over the past 20 years, the league’s total value has risen from $23.46 billion to $190 billion, a 710% gain, according to Sportico. The S&P 500 index has risen about 660% during the same time span.

— CNBC’s Jake Piazza contributed to this report.