It’s been quite the year for the city’s residential real estate market.

A team of investors led by hedge fund titan Bill Ackman nabbed this year’s top buy for a $91.54 million duplex at One57.

That’s a drop from the city record $100.5 million purchase at this same Billionaire’s Row super-tower, which closed last December.

In 2015, the supertall tower trend has spread to the outer boroughs, but more supply means slower sales — and dramatic price cuts.

Speaking of that, speculators — people who buy early with the intent to sell once the building is done — should no longer expect to be making a profit; for example, people have recently sold at a loss at One57 and 15 CPW.

“The gambling days are over. Las Vegas has left Manhattan,” says Leonard Steinberg, of Compass.