IBM's quarterly revenue fell by a bigger-than-expected 11 percent as the slowdown in corporate spending hurt even one of the healthiest US technology companies.

But higher margins helped International Business Machines Corp's first-quarter profit beat Wall Street estimates, and the company affirmed its full-year earnings outlook - helping to limit the fall in IBM shares to 1.6 percent after hours.

"These were decent results in light of the challenging economy. Certainly the top line is being impacted by the weak economy," said Andy Miedler, analyst at Edward Jones.