The frenzied pace of the New York City sales market is calming down, a result of more listings on the market and slowing demand. With less competition, buyers have gained some breathing room—they can take a day or two to make an offer—something not possible in recent months.

It’s not exactly a swing from a seller’s to a buyer’s market, at least not yet—it’s more like a nudge.

You can expect a slower pace to return this summer, when the market usually ...