Boston Celtics sell for record $6.1B to little-known PE investor William Chisum
Mar 21, 2025
Key Points
- William Chisum, a virtually unknown private equity investor whose Symphony Technology Group manages $12B in tech assets, agreed to buy the Boston Celtics for $6.1B—a record price for a professional sports franchise.
- NBA team valuations have nearly doubled in recent years as the league opened ownership to private equity and sovereign wealth funds, with the three prior team sales ranging from $3B to $4B.
- Chisum retained outgoing owner Wyc Grousbeck as team governor through 2027-28, calling the move an "intelligence test" to avoid disrupting a championship-contending roster.
Summary
William Chisum, managing partner of Symphony Technology Group, agreed to buy the Boston Celtics from Wyc Grousbeck for $6.1 billion, a record price for a professional sports franchise. The deal surprised NBA insiders and private equity investors because Chisum had no public profile outside technology circles.
Chisum has no Wikipedia page and does not appear on Bloomberg or Forbes billionaires lists. His only prior Wall Street Journal quote came from STG's acquisition of McGraw Hill's construction data unit, where he said the firm looked "forward to helping the business achieve the next level of success." Symphony Technology Group, founded in 2002, invests in cloud security software and job search platforms and manages approximately $12 billion in assets according to PitchBook.
Chisum grew up in Georgetown, Massachusetts, north of Boston. He attended Dartmouth as an undergraduate and earned an MBA from Wharton before working at Baine Capital and founding STG. Co-investors in the Celtics deal include current minority owner Rob Hall, Bruce Beal of Related Companies, and Sixth Street.
Chisum kept outgoing owner Grousbeck on as team governor through the 2027-28 season, describing this move as "an intelligence test" to avoid disrupting a winning operation. The Celtics won the 2008 championship and added another last summer, positioning them to become the first repeat NBA champion since 2018.
NBA team valuations have climbed sharply. The three most recent sales before the Celtics deal ranged from $3 billion to $4 billion. The league recently allowed private equity firms and sovereign wealth funds to buy team stakes, opening the capital spigot and pushing prices higher. This contradicts claims that professional sports are losing cultural relevance. Trophy assets remain highly coveted investments regardless of profitability pressure.