The spokesman didn't say when Mr. Kanner, a managing director, would depart or who will replace him. The spokesman said Mr. Kanner declined to comment.
Mr. Kanner has been CIO at IBM since October 2007, responsible for the company's U.S. defined benefit, non-U.S. defined benefit and U.S. defined contribution plans.
The U.S. DB plan had assets of $51.72 billion and the non-U.S. DB plan had assets of $35.75 billion at year-end 2015, according to the company's latest 10-K statement filed with the Securities and Exchange Commission.
IBM had $44.3 billion in U.S. defined contribution assets as of Sept. 30, according to Pensions & Investments data.