With Indra Nooyi stepping down from the helm at PepsiCo, that leaves only two dozen female CEOs among the companies today.

Nooyi in particular, having served 12 years as CEO at Pepsi, was viewed as a role model for other women in business. She led the world's second-largest food and beverage company through tumultuous times in the industry, setting the tone for a new behemoth in snacking to emerge. Now, President Ramon Laguarta will be taking her place later this year.

Other top women CEOs in the consumer and retail industries today include Michele Buck at Hershey, Mary Dillon at Ulta and Michelle Gass at Kohl's. A handful of women also hold the chief executive title in the health care, automotive and industrials sectors. One upcoming change to the list, Kathy Warden is set to become the CEO of Northrop Gruman, effective Jan. 1 of next year.

Though women earn more degrees than men, on average, and make up nearly half the labor force in the U.S., women are less represented in management positions the higher up they go, according to Catalyst, a nonprofit that promotes women in the workplace. Even with corporate board seats, the "overwhelming majority" of new directorships continue to go to men, Catalyst said.

Below is a list of the 24 women still serving as chief executive officers among the S&P 500 companies today, listed in alphabetical order by last name: