The reigning NBA champions could soon be under new ownership.

In a surprise announcement Monday, Celtics majority owner Wyc Grousbeck revealed he plans to sell the storied NBA franchise in the coming months, citing “estate and family planning considerations.” The team expects the sale of a “majority interest” to be finalized by early 2025 at the latest, with “the balance closing in 2028.”

Grousbeck and his partners helped return the Celtics to prominence during their ownership tenure, which began in 2002. Over their 21 full seasons, Boston ranked third in the NBA in wins behind San Antonio and Dallas; won two championships, including one just weeks before Monday’s announcement; and reached two other NBA Finals. The Celtics rank among the league’s most valuable franchises.

The big question now is: Who’s buying?

There surely will be no shortage of suitors for the iconic hoops club, the sale of which almost certainly will be the priciest in NBA history. That title currently belongs to the Phoenix Suns, who were bought for $4 billion by Mat Ishbia, billionaire CEO of a mortgage lending company, in 2023.

Recent valuations of the Celtics range from $4.7 million (by Forbes) to $5.12 billion (by Sportico), and both of those were calculated before the team’s most recent NBA championship. So, the individual — or, more likely, ownership collective — who purchases the C’s from Grousbeck’s group will need to be willing to pay a record-setting price.

In evaluating potential buyers, a logical starting point is the Celtics’ other current ownership partners. Steve Pagliuca, who owns the second-largest share of the team behind Grousbeck, released a statement Monday saying he plans to submit a bid.

“Being a co-investor and managing partner of the Celtics has been a great honor and a labor of love,” said Pagliuca, who also owns part of Italian soccer club Atalanta, “I hope to be part of the Celtics moving forward and will be a proud participant in the bidding process.”

It will be fascinating to see whether that process also features the Boston sports scene’s other power brokers. Would Patriots owner Robert Kraft, who often sat courtside with Grousbeck at Celtics games, be interested? Might Fenway Sports Group consider adding another team to a portfolio that includes the Red Sox, Pittsburgh Penguins and Liverpool FC?

Previous reports indicated John Henry’s FSG — which has been lambasted locally for its poor handling of the Sox’s payroll — wants to pursue an NBA franchise, potentially in conjunction with longtime Celtics nemesis LeBron James. (The sound you just heard was thousands of Boston fans screaming: “No!!”)

A far more popular ex-player investor would be Celtics legend Kevin Garnett, who made a failed push to buy the Minnesota Timberwolves in 2020. Ditto for Tom Brady, who has minority ownership stakes in the WNBA’s Las Vegas Aces and English soccer club Birmingham City and is seeking approval for another with the Las Vegas Raiders.

Shifting back to established Boston ownership, how about the Jacobs family, owners of both the Celtics’ fellow TD Garden tenant and the arena itself? Bruins CEO Charlie Jacobs said in a recent interview that he “of course” would be interested in potentially buying another team.

“I’d love to,” Jacobs told The Boston Globe. “I don’t have a target in mind and I would be very cautious about saying anything at this moment in time about what might be on the horizon. But yeah, of course, of course.”

Whether Jacobs had any idea about the Celtics’ impending sale when he made that comment is unclear. It highlights one potential sticking point, however: that the Celtics play in a building owned by a different professional team, removing a lucrative revenue stream.

The other factor that could give would-be suitors pause is that Boston’s current championship-winning roster soon will become exorbitantly expensive. The Celtics will be able to keep that group intact for the upcoming season with relative ease, but after agreeing to terms on new contract extensions for Jayson Tatum (five years, $314 million) and Derrick White (four years, $125.9 million), they’re on track to be hammered by the NBA’s new luxury tax and repeater tax penalties in 2025-26.

The details behind all of that are complicated, but the Celtics’ check-signers are staring at a 2025-26 payroll of around $225 million, plus north of $200 million in penalty payments that’ll make them the most expensive basketball team ever assembled.

Grousbeck’s decision to sell now — and sell very, very high — offloads that burden onto someone else. And since the new owners likely will need to pony up somewhere in the neighborhood of $5 billion to buy the team, they should have the financial flexibility to navigate these roster-related hurdles.

Even with an uber-expensive roster and without the added benefit of a team-owned arena, Grousbeck will be flooded with offers. Sales of NBA franchises have become increasingly common in recent years, but it’s rare for one with as much history and brand equity as the Celtics to hit the market.

It’ll be on Grousbeck, a Worcester native and lifelong Celtics fan, to ensure his deep-pocketed successors are worthy of that responsibility.

“(We are) committed to finding a worthy incoming ownership group who will guide the Celtics to more decades of success,” he said in an email to Celtics staffers obtained by The Associated Press. “… There will be a thoughtful and thorough process to find a buyer that recognizes the importance of Celtic Pride on the court and in the community.”