No open houses, no advertising and not a single online photo. And yet a $27 million town house on the Upper East Side and an $850,000 two-bedroom co-op in Lower Manhattan had no problem finding buyers in the past six months. Neither home was listed on the open market.

Off-market deals, known as whisper listings, have long been the purview of the ultra-high-end market. Certain properties, often with price tags of $20 million or more, are shopped with a shroud of mystery among a small circle of well-connected agents instead of being put on the market for the world to see.

Now this hush-hush approach has spread to many price points, including apartments below $1 million, as sellers realize the advantage they have, thanks to the lack of apartments available for sale in Manhattan.

“Sellers feel cocky. Sellers feel like they have the ball,” said Brian K. Lewis, an associate broker at Halstead Property who in the last six months has taken on seven whisper listings from clients who do not want to list their apartments, but are willing to entertain offers. These range from a two-bedroom for $1.295 million on the Upper West Side to a downtown loft for $12 million. “In an improving economy with no inventory, they have the asset people want.”