The estate, once owned by a family that helped start what is now U.S. Steel, dates back to the late 19th century. The main house is a 13,500-square-foot mansion with eight bedrooms and eight bathrooms. There also is a three-bedroom gatehouse and a two-bedroom carriage house with a clock tower.

The estate includes a swimming pool, a grass tennis court, an apple orchard and two private beaches along Long Island Sound.

Daniel Milstein/ Sotheby’s International Realty via AP

“We always have significant demand for Greenwich waterfront,” listing agent Leslie McElwreath of Sotheby’s International Realty said. “This is the ultimate in Greenwich waterfront in terms of the overall acreage size and the unprecedented amount of shoreline associated with it.”

McElwreath said the property, which last sold in 2014 for about $120 million, was listed in February at $150 million and ultimately sold for $138,830,000. She would not disclose the buyer or seller.

The Wall Street Journal reported the seller is a limited liability company tied to Bridgewater Associates, the hedge fund founded by billionaire Ray Dalio.

It is the most expensive home ever sold in Connecticut, McElwreath said.

“It was when it was last sold and I can tell you we have not had a sale to exceed it since then,” she said. “I cannot tell you where it stands in terms of sales in the United States. … I’d say it’s in the top 20, but it’s almost impossible to verify that particular number.”