(Bloomberg News) Companies in the U.S. unexpectedly cut jobs in September, data from a private report based on payrolls showed today.

Employment decreased by 39,000, the biggest drop since January, after a revised 10,000 rise in August, according to figures from ADP Employer Services. The median estimate of 37 economists surveyed by Bloomberg News called for a 20,000 gain. Forecasts ranged from a decline of 44,000 to a 75,000 increase.

A loss of jobs raises the risk that consumer spending, the largest part of the economy, will retrench and halt the recovery. A Labor Department report in two days will show companies added 75,000 workers last month, economists project.

"It's more evidence of a lousy labor market," said Joshua Shapiro, chief U.S. economist at Maria Fiorini Ramirez Inc. in New York. "Here we are, 18 months into a recovery and we're not doing much on the job front. Until we digest the excesses built up over decades, you're not going to see sustained gains in jobs or the overall economy."

Most stocks dropped and Treasury securities rose as the report raised concern over the outlook for employment. The Standard & Poor's 500 Index fell 0.1 percent to 1,159.97 at the 4 p.m. close in New York. The yield on the benchmark 10-year Treasury note, which moves inversely to prices, dropped to 2.39 percent from 2.47 percent late yesterday.

Prior Misses

Over the previous six reports, ADP's initial figures were closest to the Labor Department's first estimate of private payrolls in May, when it overestimated the gain in jobs by 14,000. The estimate was least accurate in April, when it underestimated the employment gain by 199,000.

ADP's initial August estimate showed a 10,000 drop in private employment compared with the government's estimate of a 67,000 increase.

"This is a disappointing result," Joel Prakken, chairman of St. Louis-based Macroeconomic Advisers LLC, which produces the figures with ADP, said of today's figures on a conference call with reporters. "It's going to be a while before employment really perks up."

High unemployment, public debt and fragile banking systems pose risks to global prosperity, according to a report today from the International Monetary Fund, which urged policy makers to take bolder steps to assure a sustained recovery.