The guy who runs IBM's big services unit that means so much to it - pulling in maybe 57% of its revenues - is going to retire on March 31.

Mike Daniels was supposedly in contention to replace former CEO Sam Palmisano but lost out to sales chief Ginni Rometty a year ago.

He's been with the company for 36 years and was reputed to have cut costs and tickled Blue's margins.

IBM has yet to name a replacement. The company said responsibility for the group would fall to Bridget van Kralingen and Erich Clementi with both reporting to Rometty.

Kralingen, 49, runs the group that provides consulting services and develops and manages software apps. Clementi, 54, runs the part of the business that outsources technology systems and business functions such as CRM.

"It is hard to summarize what Mike has meant to our company and to so many clients and IBMers around the world," Rometty wrote in an e-mail to IBM staff Friday. "Mike is a builder. He helped create our services business, which today generates more than half of IBM'S revenue and employs more than half of our global workforce."

Bloomberg said "Daniels fired thousands of employees and moved jobs to lower-cost regions such as India to trim expenses and boost profits. IBM has a five-year plan to reach annual operating earnings of at least $20 a share by 2015, up from $13.44 in 2011."