Chip Chop, the waterfront estate at the entrance to Lake Tashmoo owned for decades by television journalist Diane Sawyer, was sold today for $23.9 million.

The buyer was not disclosed, but it is believed to be real estate investor David Malm, who is listed as manager of an LLC associated with the sale.

The property was under agreement within weeks and the sale was completed less than three months after Ms. Sawyer put the 20-acre estate on the market.

Originally built for the actress Katharine Cornell and completed in 1945, Chip Chop includes a main house that retains many of its original features, a series of cottages, a tennis court and a pool.

The sale was handled by Wallace & Co. Sotheby’s International Realty in Edgartown. Mark Jenkins was the principal listing broker and Tom Wallace represented the buyer.

In a statement, Mr. Wallace said the buyer “has purchased the property for personal enjoyment and to preserve it as an important piece of Island history.”

Mr. Malm, managing director of Waltham-based Webster Equity Partners, has a home in Edgartown and has been buying up additional residential properties in town over the past several years. He now owns 10 high-end homes in Edgartown either personally or through Goldeneye, a real estate investment company he controls.

Long a landmark for boaters on Vineyard Sound, Chip Chop has been owned since 1995 by Ms. Sawyer and her late husband, the acclaimed film director Mike Nichols.

In an exclusive interview with the Gazette in August, Ms. Sawyer talked about her decision to sell.

“We thought about it long and hard . . . we’ve been so lucky to be in this amazing home for 28 years, but as our summers became more about time spent differently, with children in camps and travel, it seemed time to let someone else fall in love with this magic place,” she said.