NEW YORK CITY-SecondMarket Holdings, Inc. has leased 50,000 square feet at 636 Avenue of the Americas, making the provider of alternative investments the building’s anchor tenant.

The building was the first property bought by Billy Macklowe, CEO of William Macklowe Co., after leaving his father’s firm last year. It was purchased with Clarion Partners--then ING Clarion Partners--for $45.2 million.

SecondMarket will occupy floors three through six as well as the penthouse, in a move from 26 Broadway anticipated to take place in early 2012. Matthew Astrachan, a Jones Lang LaSalle vice chairman who represented the William Macklowe Co. and Clarion Partners in the lease, tells GlobeSt.com that the new tenant will also have signage in the lobby and some branding on the outside of the building as well.

Located in an area popular among tech firms, Astrachan says that interest among such groups in the space was high. “We actually saw a tremendous amount of activity from the media companies, the tech companies and the like,” he says. “And I think that’s partially attributable to Googe’s commitment, but also the amenities around there serve the employees pretty well.”

The other members of the JLL team representing the landlord were vice chairman Mitchell Konsker, VP Jonathan Tootell and associate Matt Ginberg. JLL also repped SecondMarket and that team consisted of SVPs Jim Wenk and Paul Formichelli, VP Dan Suozzi and associate John Lewis.

Billy Macklowe says that tech interest in the space was high--also citing Google’s presence nearby at 76 Ninth Ave. as a reason. “There is such a diversity of tenancy in that market and Google planting their flag is only furthering the appeal and the demand,” Macklowe says. Also of note as far as the space’s appeal is the work-live environment that a Chelsea office provides. Both Astrachan and Macklowe mention it as an appealing factor.

The building will see significant infrastructure upgrades, including improvements to mechanical systems and the lobby.

As for future purchases, Macklowe tells GlobeSt.com that his company is “just concluding a significant capital raise,” and intends to continue investments in the city, with a primary focus on office properties.