At first, the news deflated stock prices on Wall Street. Investors quickly shook off their worries and pushed the Dow Jones industrial average high enough to come within 11 points of 13,000 — a high point it has never crossed. But at the close of the trading day stocks finished mixed, with the Dow closing up 34.54 points, to 12,953.94.

The Realtors association’s report reflected a housing market that became increasingly unfriendly to those looking to sell their homes last month. While the number of unsold existing homes for sale fell 1.6 percent in March, to 3,745,000, it took longer to sell a home. There was a 7.3-month supply of unsold properties last month, up from a 6.8-month supply in February.

The backlog grew even as prices dropped. The median price of an existing single-family home decreased 0.9 percent last month, to $215,300, compared with a year earlier. Total sales compared with a year earlier were off 11.3 percent.

“Because demand is weak, and because inventories remain high, there’s little ability for prices to rise,” said Celia Chen, director of housing economics at Moody’s economy.com. Ms. Chen speculated that the overall inventory number may have declined last month because sellers were pulling their homes off the market in frustration.

“The overall trend in housing is still weak,” she said.

The sharp fall in existing home sales last month was a sign that the increases earlier this year were not in line with the market’s underlying path.