Also in that group are Michael Callahan, executive vice president, general counsel and secretary; Blake Irving, executive vice president and chief product officer; Ross Levinsohn, executive vice president, Americas; Rich Riley, senior vice president, and Rose Tsou, senior vice president. Co-founders Yang and David Filo each will continue as "Chief Yahoo," providing counsel to Morse and the Executive Leadership Council.

Bartz's tenure as CEO began in January 2009 after Yang announced plans to step down. Her choice followed an extensive courtship, during which Microsoft tried to acquire Yahoo, but which eventually turned into a partnership between the companies.

That partnership hasn't paid off nearly as well as Yahoo hoped. , and its display advertising business, where it historically was a leader, has begun to suffer too.

"It's not a surprise" to see Bartz go, said Greg Sterling, an analyst at Sterling Market Intelligence.