NEW YORK (CNN/Money) - Signs that the economy is much weaker than previously thought, coupled with disappointing results from Exxon Mobil sent U.S. stocks lower early Thursday.

Around 10:05 a.m. ET, the Dow Jones industrial average lost 91.24 to 8,645.35. The Nasdaq composite fell 13.77 to 1,314.49. The Standard & Poor's 500 dipped 10.71 to 900.91.

The Institute for Supply Management's July manufacturing index fell to 50.5 from 56.2 in June. That was well below expectations of a 55 reading and just slightly above the 50 level that signals expansion.

Construction spending fell 2.2 percent in June, instead of the 0.2 percent rise economists expected. The May figure was revised to a 2 percent drop from the originally reported 0.7 percent dip.

The number of Americans filing new claims for unemployment rose to 387,000 last week from a revised 367,000 in the previous week, the Labor Department said. Economists surveyed by Briefing.com were expecting 385,000 new claims.

Oil producer and Dow component Exxon Mobil (XOM: down $1.44 to $35.32, Research, Estimates) reported lower second-quarter earnings that missed estimates, due to a decline in its oil exploration business.

In technology, shares of Adobe Systems (ADBE: down $6.27 to $17.69, Research, Estimates) fell after the graphics software maker cut its third-quarter forecasts late Wednesday, citing weak July sales. On Thursday, brokerage Credit Suisse First Boston cuts its third- and fourth-quarter estimates, and lowered its 2002 and 2003 forecasts for the company.

After months of accounting scandals, one development that might bode well for stock investor sentiment was news that former WorldCom chief financial officer Scott Sullivan has surrendered to federal authorities. He's expected to face fraud charges.

European markets dipped at midday, while Asian-Pacific stocks finished mostly lower Thursday.

Treasury prices rose modestly, sending the 10-year note yield down to 4.44 percent from 4.46 percent late Wednesday. The dollar gained versus the yen and euro.

Brent oil futures rose 16 cents to $25.60 a barrel in London. Gold was lower in U.S. trading.