In an important night for gauging the health of the economy and technology spending, IBM (NYSE: IBM) posted blow-out quarterly results late Thursday, but disappointing earnings reports from Microsoft (NASDAQ: MSFT) and Google (NASDAQ: GOOG) raised fears that weakness may be spreading.

IBM shares were little changed after hours despite posting second-quarter earnings of $1.98 a share on 13 percent sales growth to $26.8 billion, both well ahead of estimates, and the company raised full-year earnings guidance too.

Google, meanwhile, saw its shares fall 7 percent after reporting earnings of $4.63 a share, 11 cents below the Thomson Financial consensus forecast. Sales after traffic acquisition costs of $3.9 billion were $30 million ahead of estimates, but investors wanted more from the highflier.

Microsoft shares lost 5 percent after the company beat estimates with $15.84 billion sales but came in a penny shy of estimates with 46-cent earnings. The company's September quarter sales guidance was also below $15.06 billion estimates.

AMD (NYSE: AMD) also released its quarterly results after the bell, posting a wider than expected loss and lower than expected sales. In addition, the company replaced its CEO.

And Merrill Lynch (NYSE: MER) served as a fresh reminder of the credit crisis that has crippled Wall Street in the last year, announcing a much bigger than expected write-down of $9.7 billion.

The results came after a second day of strong gains for stocks, fueled by better than expected results from JPMorgan (NYSE: JPM) and another steep drop in oil prices. Citigroup (NYSE: C) will report its results before the market opens Friday.

eBay (NASDAQ: EBAY) plunged 14 percent after beating estimates but offering third-quarter guidance that was below analysts' estimates.

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Nokia (NYSE: NOK) was a standout, jumping 8.7 percent after beating estimates.

Dell (NASDAQ: DELL) jumped 5.5 percent on reports of strong PC sales.

ValueClick (NASDAQ: VCLK), Teletech (NASDAQ: TTEC) and Xilinx (NASDAQ: XLNX) fell on their results.

Catalyst Semi (NASDAQ: CATS) soared 58 percent on a buyout agreement with ON Semi (NASDAQ: ONNN).

The Nasdaq rose 27 to 2312, the S&P gained 15 to 1260, and the Dow surged 207 to 11,446. Volume rose to 7.2 billion shares on the NYSE, and 2.64 billion on the NASDAQ. Advancers led by a 25-9 margin on the NYSE, and 19-9 on the NASDAQ. Upside volume was 71 percent on the NYSE, and 75 percent on the NASDAQ. New highs-new lows were 31-145 on the NYSE, and 58-126 on the NASDAQ.