International Business Machines Corp., the biggest computer-services company, said the Securities and Exchange Commission is investigating how it reports revenue from offsite cloud services.

IBM is cooperating with the SEC in the probe, which it learned about in May, it said today in a filing, without providing further details. Revenue from cloud services, such as storing clients’ data and software applications remotely, rose 70 percent in the first half of 2013 from a year earlier, it said in the filing, repeating a figure it has disclosed before.

Chief Executive Officer Ginni Rometty has identified cloud computing as one of IBM’s chief sources of growth amid a slowdown in demand for hardware and for consulting services. The Armonk, New York-based company has a goal of reaching $7 billion in cloud revenue by 2015.

IBM fell as much as 1.7 percent in early trading today. It had closed yesterday little changed at $196.01.

Florence Harmon, an SEC spokeswoman, declined to comment. James Sciales, an IBM spokesman, didn’t immediately respond to messages requesting comment.

Since it’s not a physical good, software can present difficulties for accounting enforcement. About half of publicly traded software companies since 1990 have had to restate revenue because of misclassification of sales and product returns, or because they categorized ongoing payments for tech-support services as a sale of a product license, Michael Cusumano, a management professor at the Massachusetts Institute of Technology’s Sloan School of Management, said in November.

Autonomy Writedown

Hewlett-Packard Co., IBM’s archrival in the computer- services business, took an $8.8 billion charge last year to write down the value of Autonomy, a software company it acquired, amid allegations of accounting improprieties within the unit. Autonomy, whose products organize corporate customers’ reams of data, had used aggressive tactics to inflate its results, a former executive told Bloomberg News last year.

IBM doesn’t disclose how much revenue it gets from cloud computing, which is spread across several divisions. Its 70 percent growth rate in the first six months of 2013 was a slowdown from 80 percent in the fourth quarter.

Earlier this month, IBM acquired SoftLayer Technologies Inc., a cloud-computing storage provider. IBM paid almost $2 billion for Dallas-based SoftLayer, according to a person familiar with the deal.

Market researcher IDC estimates the cloud-computing market may more than double to $105 billion by 2016 from last year. SoftLayer specializes in public clouds — data-center networks that manage computing and software for businesses remotely. IBM is pairing those capabilities with private-cloud operations, building dedicated systems for individual customers.