In the vast majority of transactions, an agent lists a home for sale on a local database and markets the property widely to drum up interest and get the best price. But in certain cases, a broker will show an unlisted property to a small circle of potential buyers more exclusively, often in hope of getting a deal done quickly.

These private sales are known as pocket listings, or whisper listings. They have been around for many years. But they are on the rise now even though the National Association of Realtors adopted a rule last year aimed at discouraging their use following complaints from some of its members.