Investors extended their sell-off of blue chips on Thursday as oil prices continued to climb, renewing Wall Street's concerns that high energy costs would deflate third-quarter earnings. Only the Nasdaq composite index managed a minimal gain.

Analysts said oil prices would keep consumer spending down and business costs rising, a combination that will squeeze profit margins and lower third-quarter earnings.

Oil prices were also blamed, in part, for a lower reading on the Conference Board's index of leading economic indicators, the third straight monthly decline. Investors said the forward-looking index sent a signal that economic growth has been slowing and would likely taper off through the end of the year.

"When you take a look at the leading economic indicators, it's very clear that the price of oil is having an impact on the economy," said Hugh Johnson, chief investment officer at First Albany Corp. "Just look at the negative earnings statements from some of the most stable companies out there. If the markets are going to move higher, we're going to need some relief on the oil front so that the earnings picture improves."

The Dow Jones industrial average fell 70.28, or 0.7 percent, to 10,038.90, its lowest level since Aug. 17. The Standard & Poor's 500-stock index dropped 5.20, or 0.5 percent, to 1108.36, while the Nasdaq composite index gained 0.72, or 0.04 percent, to 1886.43.

One day after Morgan Stanley's disappointing earnings dragged on the brokerage sector, A.G. Edwards reported results that also fell short of expectations. The company's stock edged 12 cents higher, to $34.59, even though A.G. Edwards missed estimates by 3 cents per share. Morgan Stanley rebounded 80 cents, to $49.52.

A downgrade of the entire petroleum sector by Deutsche Bank weighed heavily on energy stocks, particularly on Exxon Mobil, which dropped $1.10, to $47.76.

Martha Stewart Living Omnimedia jumped $2.57, to $17.55, after the company announced an agreement with reality television producer Mark Burnett to collaborate on new TV programming.

Other Indicators

* The New York Stock Exchange composite index fell 27.13, to 6521.43; the American Stock Exchange index rose 6.78, to 1261.46; and the Russell 2000 index of smaller-company stocks fell 0.09, to 565.80.

* Declining issues outnumbered advancing ones by 6 to 5 on the NYSE, where trading volume fell to 1.28 billion shares, from 1.38 billion on Wednesday. On the Nasdaq Stock Market, decliners outnumbered advancers by 7 to 6 and volume totaled 1.38 billion, down from 1.58 billion.

* The price of the Treasury's 10-year note fell $3.13 per $1,000 invested, and its yield rose to 4.02 percent, from 3.98 percent on Wednesday.

* The dollar rose against the Japanese yen and fell against the euro. In late New York trading, a dollar bought 110.55 yen, up from 110.52 late Wednesday, and a euro bought $1.2314, up from $1.2262.

* Light, sweet crude oil for November delivery settled at $48.46, up 11 cents, on the New York Mercantile Exchange.

* Gold for current delivery rose to $410.90 a troy ounce, from $407.20 on Wednesday, on the New York Mercantile Exchange's Commodity Exchange.