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The Boston Celtics majority ownership group, led by Wyc Grousbeck, is planning to make the franchise available for sale.

Grousbeck and partner Steve Pagliuca led a group that purchased the team in 2002 for $360 million. Since then, franchise valuations have skyrocketed, with the latest teams to sell controlling shares being the Phoenix Suns, which went for $4 billion to Mat Ishbia in February 2023, the Milwaukee Bucks, with Jimmy and Dee Haslam paying $3.5 billion several weeks later, and the Dallas Mavericks, with the Adelson and Dumont families paying $3.5 billion in December.

The Celtics are one of the iconic franchises in professional sports, with an NBA record 18 NBA titles -- trailing only the New York Yankees (27) and Montreal Canadiens (24) among all North American professional sports leagues.

In a statement announcing the decision Monday, the Celtics revealed that the managing board of the ownership group expects to sell a "majority interest" in the team either this year or early next year, and that it "expects Wyc Grousbeck to remain as the Governor of the team until the second closing in 2028."

Since the Grousbeck-led group Boston Basketball Partners purchased the team, the Celtics have consistently been among the league's best teams. They've won two championships -- including the title last month with a five-game victory over the Mavericks in the NBA Finals -- and reached the NBA Finals on two other occasions.

Over that span, Boston is third in regular-season victories, trailing only the San Antonio Spurs and Mavericks -- the three teams with over 1,000 regular-season victories during that period -- and are second to the Miami Heat in playoff victories.

Sources told ESPN's Adrian Wojnarowski on Monday that Boston has agreed to a four-year, $125.9 million extension with Derrick White. The Celtics also agreed to sign Jayson Tatum to a five-year, $314 million extension --  the largest contract in NBA history -- as they continue to lock in the core of a team that won 64 games and finished with a 16-3 record in the playoffs. That is the second-best winning percentage in NBA postseason history since the playoffs expanded to four seven-game series.