It also makes for rapid-fire sales. The amount of time that listings spent on the market fell 20 percent to a record low of 73 days in the third quarter, according to the Douglas Elliman report. “You have to be very competitive and you have to be quick,” especially at the lower end of the market, Ms. Herman said. “I tell people, ‘You really have to have your ducks in order financially and know the market yourself.’ ”

Overall, the number of closed sales was up for the quarter, driven by robust closings in new development. While prices remained high across all market segments, the average sales price for the luxury market, defined as the top 10 percent of closed sales, dropped 12 percent in the third quarter, to $6.73 million, compared with $7.68 million during the same period last year, as fewer luxury properties closed, according to the Corcoran report.

The highest third-quarter sale was in new development: a $37.9 million penthouse at the Charles condominium at 1355 First Avenue on the Upper East Side. In the resale market, there were only two recorded sales of more than $20 million: a $30 million co-op at 1040 Fifth Avenue, also on the Upper East Side, and a $22 million apartment at 15 Central Park West, on the Upper West Side.

Buyers may be reaching a breaking point when it comes to outsize prices for luxury real estate. “At the upper end of the market, I believe there is a little bit of a pushback from the buyers,” said Diane M. Ramirez, chief executive of Halstead Property, which found that the average sales price of co-ops with at least three bedrooms declined 26 percent to approximately $3.1 million in the third quarter of the year, from $4.2 million during the same period last year.

Hall F. Willkie, president of Brown Harris Stevens Residential Sales, said that though demand remained strong, “more sellers are asking prices that are just not justified.” Especially at the high end, he said, “there’s a glut of inventory that’s overpriced.”