NEW YORK CITY-In a leasing deal in the works since last spring, global trading group Li & Fung Ltd. has signed on for nearly 490,000 square feet at the Empire State Building. The New York Post first reported the deal Thursday morning; an industry source confirms the Post report. Separately, Malkin Holdings, which oversees the 2.8-million-square-foot skyscraper at 350 Fifth Ave., said Thursday it would buy more than 50 million kilowatt hours of wind power per year from Green Mountain Energy.

The massive 15-year lease, topping last year’s biggest Manhattan deal, reportedly calls for Li & Fung to occupy several floors in the base of 350 Fifth, part of the W&H Properties portfolio. It’s the most dramatic success story to date in W&H’s campaign to reposition the Midtown icon for larger space users, a tenant class largely unknown for most of the tower’s 80-year history.

According to the Post, Li & Fung’s existing blocks of space at W&H’s 1333 Broadway and 1359 Broadway will not be affected by the new deal. Cushman & Wakefield’s Mitchell Konsker and Alexander Chudnoff, who left the firm on Wednesday for Jones Lang LaSalle, negotiated for Li & Fung in the 350 Fifth deal, according to the Post. A Newmark Knight Frank leasing team led by William Cohen represented W&H.

Through a spokeswoman, Malkin Holdings president Anthony Malkin declines to comment. A Li & Fung spokeswoman says it's the company's policy not to comment on news reports. The Hong Kong-based firm has been stepping up its US presence, acquiring Oxford Apparel for $121.7 million this past November and launching licensed Jennifer Lopez and Marc Anthony collections.

This past December, CB Richard Ellis announced what was Manhattan’s largest office lease of 2010, a 444,000-square-foot relocation by Societe Generale to 245 Park Ave. for its US headquarters. CBRE represented the tenant in that 20-year deal, while 245 Park landlord Brookfield Properties was represented in-house.

In the wind power deal announced Thursday, Malkin Holdings has signed a two-year contract for nearly 55 million kilowatt hours annually with Austin, TX-based Green Mountain. It will take the form of renewable energy certificates from NRG Energy, Green Mountain’s parent company.  

“It was a natural fit for us to combine 100% clean energy with our nearly completed, ground-breaking energy efficiency retrofit work,” Malkin says in a release. “Clean energy and our nearly 40% reduced consumption of watts and BTUs gives us a competitive advantage in attracting the best credit tenants at the best rents.”

Adds Paul Thomas, CEO of Green Mountain, “This announcement is historic for many reasons. In addition to being the largest commercial consumer of green power in New York City, the Empire State Building’s renewable power purchase is now the largest purchase in our company’s 13-year history.”