(Fortune) -- Abigail Johnson, President, Fidelity Employer Services of Fidelity, ranks No. 18 on Fortune's 2006 list of 50 Most Powerful Women.

Ned Johnson moved Abby, his daughter and presumed heir, from the core mutual fund business last year after performance slipped. Still, she remains a major shareholder (though she transferred some of her shares to family trusts last year). The succession question looms, and running the fast-growing benefits business may be a requisite for the top job.

By the key criteria Fortune uses in assembling its annual list - the size, importance, and health of each business in the global economy, and the momentum of each woman's career (along with her social and cultural influence) - there's no question that the power of women in the corporate sphere is rising.

Indeed, it could be called the year of the Most Powerful Woman CEO. The top seven positions on Fortune's 2006 Most Powerful Women list are held by CEOs.

Some other pwerful women on the list include: Anne Sweeney, Disney Media Networks (Charts); Sallie Krawcheck, Citigroup (Charts); Susan Arnold, Procter & Gamble (Charts); Charlene Begley, General Electric (Charts); Mary Minnick, Coca-Cola (Charts); Linda Dillman, Wal-Mart (Charts); and Susan Ivey, R.J. Reynolds Tobacco (Charts).

Next: Full list: 50 Most Powerful Women at http://money.cnn.com/popups/2006/fortune/mostpowerfulwomen/1.html

Plus: Most Powerful Women: 10 Highest-Paid at http://money.cnn.com/popups/2006/fortune/womenpay/index.html