As part of its world record $5.46 billion purchase of Stuyvesant Town and Peter Cooper Village, Blackstone has tucked away air rights that could be worth some $625 million.

While the majority of the air rights — roughly 1 million square feet — will be transferred somewhere over the city’s rainbow through a new entity, Blackstone also retained 250,000 feet of air rights within a Stuyvesant Town associated LLC.

These include 200,000 square feet for a community facility, 25,000 square feet for residential and 25,000 square feet for commercial use.

But before residents and elected officials freak out, Blackstone sources said the company is sticking with its promise and will not build anything else on site. The executives spoke on condition of anonymity and explained the deed filings merely divvied up the air rights between various entities.

As for the main tranche, which is roughly 1 million square feet but must still be formally calculated, possible receiving sites must also be identified. Blackstone executives are no slouches and are likely to find a way to get top dollar for these transferable development rights, which can be sold for $500 per foot or more depending on their ultimate location.

When ready, Blackstone will take the plans through the formal ULURP process, executives insisted.

Meanwhile the world record sales price on the two deeds, $4,111,111,767 for Stuyvesant Town and $1,45,485,020 for Peter Cooper, added up to $5,456,596,787. Roughly $11 million of that included “personal property” such as offices equipment, mowers and the like.

Just another day at the real estate office for CWCapital, which completed the sale on Dec. 18 via Douglas Harmon of Eastdil Secured.

On Tuesday, Douglas Harmon and Jean Celestin of Eastdil Secured completed the sale of another multifamily project for CWCapital for $201 million.

Riverton in East Harlem has 1,229 units in a dozen buildings on eight gated acres. Here, in agreement with the city, 70 percent of the units will remain affordable.

Douglas Eisenberg of A&E Real Estate Holdings made the purchase with Harvard endowment funds.

Progenics Pharmaceuticals will become the first biotech tenant at the World Trade Center.

The firm will have 26,558 square feet for its new headquarters on the south side of the 47th floor of 1 WTC.

Progenics, which is getting a build-to-suit space with an asking rent of $78 a foot, expects to spend $33.1 million over the life of the lease that ends September 2030.

There is also a five-year renewal option with a reset to then-fair market rent, Progenics revealed in a regulatory filing, which, in an unusual move, included the entire lease document.

Progenics will share the floor with Olam Group, Decryptex and a Legends’ office, along with two pre-built units.

Under its lease, Progenics has a right of first offer on any of the space that becomes available in the future. This is also subject to any rights the building’s anchor tenant, Condé Nast, may have with respect to this future expansion floor.

The biotech firm was represented by Patricia Ardigo and Joel Wechsler of CBRE.

Broker Eric Engelhardt worked for the Durst Organization in-house as well as its partners in the Port Authority of New York and New Jersey.

The ownership was also represented by a Cushman & Wakefield team led by Tara Stacom that included Justin Royce, Barry Zeller, Connor Daugstrup and Peter Trivelas.

Progenics, which is focused on developing treatments for prostate cancer, has a large campus in Tarrytown.

Women’s fashion company Alfred Dunner has signed a lease to move to 59,132 feet at 1333 Broadway where it will have the entire 11th and 12th floors.

Marc Schoen, Brian Neugeboren and Bob Savitt of Savitt Partners represented the tenant in the move to Herald Square.

The Empire State Realty Trust ownership was represented by the JLL team of Mitchell Konsker, Dan Turkewitz and Benjamin Bass. The asking rent was $56 per square foot.

Mark Weiss has taken a New Year’s Leap from Newmark Grubb Knight Frank to Cushman & Wakefield.

A vice chairman at Newmark and 30-year industry vet who also had a stint at Studley, Weiss will become executive vice chairman at C&W.

Weiss took home the Real Estate Board of New York’s Most Ingenious Deal of the Year Award twice and last year handled the purchase of a Harlem site for a hospital group to develop the Proton Beam Research and Therapy Center.

Neither brokerage nor Weiss would comment on the switch.