In a deal that was pushed to a conclusion by concerns about higher tax rates, Eugene M. Grant, a well-known investor and philanthropist in the city, has agreed to sell his controlling 50.1 percent stake in the giant St. John’s Center to an investor group that owns the other 49.9 percent.

The investors — Fortress Investment Group, Atlas Capital Group and Westbrook Partners — will pay around $250 million for the three-block-long building at 550 Washington St. that straddles SoHo and the Meatpacking District.

At 1.281 million square feet, the building is so large that westbound traffic on Houston Street runs under a cut in the four-story property, which stretches for more than 800 feet along the West Side Highway.

Grant, who heads his eponymous company, has controlled the building since the 1960s along with longtime partner Lionel Bauman and later, Bauman’s family. It was once entirely rented out to companies, including Merrill Lynch & Co.

In 2006, Westbrook bought the share controlled by the Bauman family for roughly $200 million.

Earlier this year, Westbrook sold part of that to the other investment companies, which have teamed up to buy Grant’s majority, according to sources close to the deal.

The 1933 building was developed as a freight facility and was the original terminus of the High Line. Another floor was added in the early 1960s by Grant and Bauman.

Today, its 250,000-square-foot expansive floors are the city’s largest office floorplates.

Because of the building’s high ceilings and awe-inspiring views of the Hudson River, creative and tech companies will be targeted as potential tenants by the marketing team.

The structure’s largest tenant, Bloomberg LP, renewed its lease for its 372,382-square-foot disaster recovery site last spring.

Nevertheless, most of the building remains vacant, with nearly 750,000 square feet up for lease.

There are also 290,000 square feet of air rights, which could be used for the development of an as-of-right hotel or more modern offices or for residential apartments with a change of zoning.

The parties either didn’t return calls or declined to comment.

While the transaction was made between the partners without brokers, attorneys Jonathan Mechanic represented the buyers Joshua Stein and Lawrence Kobrin teamed up to represent Grant.