East Midtown, a favored location for hedge funds and small financial firms, will soon have a prestigious new location for them.

After serving as Santander’s New York headquarters since 1991, the 134,000 square-foot boutique office tower at 45 E. 53rd St. is finally to be made available for other tenants.

A joint venture of ZG Capital and Rialto Capital Management quietly signed a contract last week on an off-market deal to buy the tower for $105 million, Realty Check has learned. The seller was Florida-based MEK Management Services. The deal will close in 30 days.

The new owners plan a $60 million-$80 million capital upgrade to modernize the soon to be vacant, 20-story jewel and create new tenant amenities.

Newmark’s Jordan Roeschlaub and Dustin Stolly arranged and structured the equity joint-venture and are arranging financing.

Santander has used the property as its New York headquarters since it was built in 1991. It sold it to MEK in 2012 but net-leased it back. The Spanish bank exercised an option to leave early this year and plans to consolidate its space at 437 Madison Ave. in the fall.

The new owners of 45 E. 53rd St. plan to attract boutique financial services firms that want full-floor presences in first-class Plaza District locations.

ZG Capital is a partnership of Bobby Zar and James Tamborlane. They recently bought the Bruckner Building office property in The Bronx. The 45 E. 53d St. purchase is the first New York City acquisition for Rialto, which is run by Jay Mantz and Jeff Krasnoff.

The tower stands adjacent to landmark Lever House, which is undergoing its own $100 million redevelopment.

Park Tower Group, owner of 535 Madison Ave., is proud that several lease extensions totaling 39,315 square feet have brought the 37-story tower to full occupancy. The extending tenants are Bain Capital NY, FTV Management Company and Garda Capital Partners.

But they’re just as happy to report that the multi-tenant property with 480,000 square feet has 94% physical occupancy based on daily headcounts — more than twice the Manhattan average of under 40% as the city continues to inch back from the pandemic.

Park Tower Group president Marian Klein said that 535 Madison “is a destination where people want to come to work,” thanks to its modern technology, top-tier amenities, public art and proximity to Grand Central Terminal.

Through a partnership between Park Tower and Christie’s auction house, the building boasts a Christie’s Sculpture Garden exhibition space in the outdoor public plaza and indoor lobby.

Sven, the Durst Organization’s towering, 71-story apartment skyscraper in Long Island City, will soon have plenty of booze to go with its views.

Queens-based Finback Brewery just signed a lease for 3,800 square feet, to open late this year — its third city location. According to its publicity, the new Finback taproom will “explore fruit-forward fermentations that are conditioned in wooden foeders and ceramic crocks.” Foeders, lest you forget, are very large barrels.

Finback co-owner Basil Lee said he’s excited to showcase their mixed-fermentation sour ales that highlight New York fruits and ingredients.

The development company’s president, Jody Durst, said Finback will be “a great addition to the neighborhood that’s home to one of the city’s premier dining destinations.”

Durst also recently announced a new green space called Sven Park, which will offer residents and the public an array of outdoor facilities.

Sven’s 958 rental units include 288 that are income-restricted. The project incorporates a landmarked, 1927 clock tower structure which Durst is restoring and converting for modern retail use.