Bill Chisholm (center) sits with Wyc Grousbeck (second from left) during Wednesday's Game 5 win.
Bill Chisholm (center) sits with Wyc Grousbeck (second from left) during Wednesday's Game 5 win.Danielle Parhizkaran/Globe Staff
Bill Chisholm has obtained sufficient commitments to purchase the Celtics and his ownership group has been finalized, according to a letter sent to existing shareholders Thursday that was obtained by the Globe.
In March, a group led by Chisholm agreed to purchase the Celtics at a valuation of $6.1 billion. At the time, Chisholm’s offer was not fully financed, although that is common in a massive deal such as this one. But his bid is now fully subscribed.
The deal will not become official until it is approved by the NBA’s Board of Governors, likely in June or July, but that is expected to be a formality.
Chisholm’s group will purchase 51 percent of the team this summer, with the balance closing in 2028. Lead governor Wyc Grousbeck is expected to remain in control until the end of the 2027-28 season.
The Thursday letter from Boston Basketball Partners lays out how the process will unfold for existing shareholders in the coming months.
Those who are not joining Chisholm’s new ownership group will be required to sell 50 percent “plus one unit” of their interest in the team and will have the option of deferring the rest until 2028. Or shareholders can sell 100 percent of their interest at first closing. Shareholders have until May 28 to disclose their elections, according to the letter.
Although Chisholm will take on the controlling stake this summer at the $6.1 billion valuation, in 2028 the remaining shares will be sold at a valuation closer to $7.3 billion, in large part due to the incoming windfall from the $76 billion media rights deal the NBA recently signed.
It is unclear what percentage of the team Chisholm is purchasing, but he is required to own at least 15 percent as lead governor.
The private equity firm Sixth Street is also expected to hold a substantial stake. But private equity firms can only be silent partners and cannot own more than 20 percent of an NBA team. Sixth Street also holds an ownership stake in the San Antonio Spurs.
Some recent reports suggested that Sixth Street and Chisholm might test the NBA’s regulations and seek a pact that allows the investment firm to take on a larger stake, but league sources insisted that that was never pursued.
Chisholm and Grousbeck have sat together in TD Garden courtside seats often in recent months, including during the Celtics’ 127-102 romp against the Knicks in Game 5 of the Eastern Conference finals Wednesday night. Chisholm was wearing a No. 0 Jayson Tatum jersey in support of the Celtics superstar who ruptured his Achilles’ tendon in the final minutes of Boston’s Game 4 loss.
Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him @adamhimmelsbach.