Updated from 4:05 p.m. EDT

Tech stocks sold off Thursday as investors -- battered by two weeks' of uneven earnings news -- were further rattled by worrisome economic data. The selling spread to the Dow, where GM ( GM) lost 6.8% on word of an SEC investigation.

The Nasdaq Composite, down 4% in October already, lost another 36.24 points, or 1.73%, to 2063.81. The Dow Jones Industrial Average tumbled 114.87 points, or 1.11%, to 10,230.11 -- its fourth triple-digit swing in seven sessions. The S&P 500 lost 12.48 points, or 1.05%, at 1178.90.

"The market was put up for sale today," said Jay Suskind, head of institutional equity trading with Ryan Beck & Co. "Tech, which has held up well lately, had its time to sell. With everything mixed into an already nervous market, there weren't any buyers around."

The selling in technology was difficult to characterize. The Philadelphia Semiconductor Index shed 2.7%, reflecting 4% losses in Advanced Micro ( AMD), Maxim Integrated ( MXIM) and Marvell Technologies ( MRVL). But bellwether chipmaker Intel ( INTC) was down just half a percent.

"There's too much worry in the market," said Barry Hyman, equity market strategist with Ehrenkrantz King Nussbaum. "The worry of inflation and a slowing economy is still there. There's been an inability to rally off an oversold market. We haven't mustered anything of importance. We've had sector breakdowns. Semiconductors and retail are in disarray and continuing downward."

Similarly, in software, Adobe ( ADBE) and Autodesk ( ADSK) were both off more than 3%

Microsoft ( MSFT), which reported earnings after the bell Thursday, finished with a 1% decline. The company posted first-quarter earnings of $3.14 billion, or 29 cents a share, up from $2.53 billion, or 23 cents a share, a year ago. Results included a 2-cent charge related to a legal settlement with RealNetworks ( RNWK).

Revenue rose to $9.74 billion from $9.19 billion a year ago but missed analysts' estimates of $9.78 billion. After the report, Microsoft was down 2% on Instinet.

GM led the decline on the Dow, while McDonald's ( MCD), Home Depot ( HD), American Express ( AXP) and Johnson & Johnson ( JNJ) all had declines of 2% or greater.

"The S&P 500 tried to stay above 1200 Wednesday , but the negativity over higher interest rates in the bond market took over and knocked the market off its perch," said Brian Williamson, an equity trader with Boston Company Asset Management. "That 1200 level is critical."

In other markets, the 10-year Treasury was up 7/32 in price to yield 4.56%, while the dollar fell against the yen and euro.

Oil gained ground after losing $1.78 a barrel on Wednesday. The December contract finished up 43 cents to $61.09 a barrel, while unleaded gasoline added a penny at $1.59 a gallon. Natural gas shed 21 cents to $13.83 per million British thermal units after an Energy Department weekly report showed that inventories were up 77 billion cubic feet.

GM said in a regulatory filing that the SEC has launched a probe into pension and other post-retirement benefits at the automaker, as well as its relationship with bankrupt auto supplier Delphi ( DPHIQ). The inquiry concerns financial reporting with respect to the pension benefits and the "recovery of recall costs from suppliers and supplier price reductions or credits," GM said.

Reuters quoted a spokesman in Europe repeating CEO Rick Wagoner's statement that "Chapter 11 is simply not an option for GM." Shares of GM dropped $1.98, or 6.8%, to $27.19.

On the economic front, the Commerce Department reported that durable-goods orders fell 2.1% in September, a larger-than-expected decline. Excluding transportation, orders fell 1%. Shipments of durable goods increased 0.1% in September, while inventories of durable goods slipped 0.1%.

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