The fund could smooth the transaction process for NBA owners and their limited partners at a time when steep price tags have made it difficult to offload stakes.
The NHL has no rules prohibiting private equity firms from holding ownership stakes in franchises.
Arizona Cardinals' Josh Shaw was suspended through 2020 for betting on games.
MLB changed its bylaws earlier this year to allow investment funds to acquire minority stakes in multiple teams.
Previous private equity investments in pro football have taken various forms and have not been limited to the NFL.
After getting kicked around for years, Arena Football has declared bankruptcy.
For existing owners of professional franchises, private equity firms would provide a new pool of potential investors.