International Business Machines Corp reported better-than-expected quarterly revenue, helped by continued growth in the company's cloud and analytics businesses.

Under Chief Executive Ginni Rometty, the company has shifted towards more profitable areas such as cloud services, analytics and security.

Revenue from those areas, which the company calls "strategic imperatives", rose 16 per cent to US$8 billion in the third quarter.

Cloud revenue jumped 44 per cent, compared with a 30 per cent rise in the second quarter.

The company also maintained its full-year adjusted earnings forecast of at least US$13.50 per share.

Shares of IBM were marginally lower at US$153.50 in after-market trading on Monday.

IBM reported its smallest drop in quarterly revenue in more than four years.

The company's revenue marginally fell to US$19.23 billion in the quarter ended Sept. 30 from a year earlier, but beat the average analyst estimate of US$19 billion, according to Thomson Reuters.

Net income fell to US$2.85 billion, or US$2.98 per share, from US$2.95 billion, or US$3.01 per share.

Excluding items, IBM earned US$3.29 per share, beating analysts' average estimate of US $3.23 per share.

Up to Monday's close, the Dow component's shares had risen nearly 12.5 per cent this year, outperforming the 3.8 per cent gain in the broader index.