"The controlling family of the ownership group, after considerable thought and internal discussion, has decided to sell the team for estate and family planning considerations," the team announced in a statement.

The managing board of the ownership group expects to sell a majority interest in 2024 or early 2025, with the balance closing in 2028, and expects Grousbeck to remain as the Governor of the team until the second closing in 2028, the team added.

Grousbeck and partner Steve Pagliuca led a group that purchased the team in 2002 for $360 million (£285m), ESPN reported.

The value of teams has skyrocketed since then with the Phoenix Suns reportedly selling for $4 billion (£3.16bn) in February 2023 and the Milwaukee Bucks and Dallas Mavericks fetching $3.5 billion (£2.77bn) each since then.

The Celtics beat the Dallas Mavericks 4-1 in the best-of-seven finals on June 17th to deliver the storied franchise an NBA best 18th championship.

Boston are favorites to repeat next season with the duo of finals MVP Jaylen Brown and forward Jayson Tatum.