Wang had owned the Islanders since 2000.
Ledecky released the following statement Friday:
"It is a privilege to become the majority owners of the New York Islanders Hockey Club, and we thank Charles Wang, NHL Commissioner Gary Bettman and our fellow National Hockey League owners for their support in making this possible.
"We are grateful for this opportunity to build upon the Islanders' rich history, which includes four consecutive Stanley Cup Championships. We also look forward to working with a superb team on behalf of the incredibly passionate Islanders fans.
"[General manager] Garth Snow and [coach] Jack Capuano, who led the Isles to an exciting playoff run in 2016, have our full confidence. We commit ourselves to doing what it takes to bring our fans and the team a fifth Stanley Cup, and eagerly await the home opener at Barclays Center on October 16th."