U.S. economic concerns and a worsening European financial crisis have hurt consumer demand, but companies such as IBM which sell hardware and software for giant data centers powering the Internet have benefited from resilient enterprise spending.

International Business Machines Corp said full-year diluted earnings would be at least $13.35 per share, up from its prior forecast of at least $13.25 in July.

But the Armonk, New York-based company's stock fell 2.46 percent to $182 in extended trade after closing down 2.07 percent on the New York Stock Exchange.

Signings in the quarter were $12.3 billion, in line with some analysts' expectations of $12 billion to $13 billion.

Revenue rose 8 percent from a year earlier to $26.2 billion, in line with the average forecast of $26.26 billion, according to Thomson Reuters I/B/E/S.

IBM reported third-quarter profit, excluding items, of $3.28 per share, up 15 percent year over year.