The American service sector contracted in July — though less than expected — as new orders decreased and prices rose, stifling growth for truckers, retailers, and insurers.

The Institute for Supply Management, a trade group of purchasing executives, said today its reading of the service sector was 49.5 in July, up from 48.2 in June. It beat economists’ prediction of a reading of 49.0, according to the consensus estimate of Wall Street economists surveyed by Thomson/IFR.

A reading below 50 signals contraction, while a reading above 50 indicates growth.

In morning trading, the Dow Jones industrial average rose 185.71 to 11,469.86. The Nasdaq composite rose 32.18 to 2,317.74 and the Standard & Poor’s 500 rose 18.94 to 1,267.95.

Economists, however, were more sanguine about the report. John Ryding of RDQ Economics described it as “partly a sentiment index. If things are not getting as bad at a slower rate, it can feel like improvement.”

“Qualitatively, it changes nothing about our assessment of the economy: Growth is at best weak and inflation pressures remain elevated,” he said. “That adds up to a one-word theme: Stagflation.”

Improvement in the index was “so marginal, it’s impossible to say” what caused it, Mr. Ryding said.

The industries that reported growth include entertainment, recreation, scientific and technical services, utilities, hotels, and restaurants.

The survey showed that prices continued to rise, as they have for the past five years, but the rate of increase was slower in July than it was in June.

In a good sign, companies said their order backlogs grew in July. New export orders fell, however.

The president of InterMart Inc., an eight-person import-export software company, David Noah, said sales are flat and “it’s taking longer for companies to pull the trigger on a purchase.”