From the November issue: In the fall of 2008, real estate broker Michael Garr was approached by a former client who had bought a large apartment in a tony building the previous spring. The client, who worked in finance, needed to downsize to a less expensive place after the Lehman fallout. But there was a catch: Garr had to keep the plan a secret, because the client hadn’t yet told his wife he was facing financial difficulty. “He didn’t want to upset her and the kids,” said Garr, the founder of Garr and Co., which was acquired this year by the residential brokerage Core. “He wasn’t going to consult her until he had some options.” High-end brokers have always prided themselves on being discreet. But like Garr, many are finding that secrecy has become more important than ever. “Whisper listings” — properties that are for sale, but not officially on the market — are becoming more common, as sellers seek to avoid the perception that they are unloading properties because of financial distress. Also known as “quiet listings,” they are often among the most expensive properties in the city.