IBM President and CEO Virginia Rometty is taking on the added role of chairman, as Samuel Palmisano prepares to retire at the end of this year.

The technology company said Tuesday that Rometty, 55, will take on the expanded role Oct. 1. Palmisano, 61, will serve as a senior adviser until he retires in December.

Rometty, the company's former sales and marketing chief, became IBM Corp.'s first female CEO in January. Joining the Armonk, N.Y.-based company in 1981 as an engineer, Rometty later was instrumental in the formation of IBM's business services division, including overseeing the $3.5 billion purchase of PricewaterhouseCoopers' consulting business in 2002.

IBM has sustained a nearly decade-long streak of earnings growth as it shook off the economic jitters that have undercut several other technology companies.