German Chancellor Angela Merkel is 'Forbes' most powerful woman

— -- Women are making waves in business, politics and nonprofits around the world. Their influence is growing.

Forbes' Power Women list isn't about celebrity or popularity; it's about influence. Queen Rania of Jordan (No. 75) is perhaps the most listened-to woman in the Middle East; her Twitter feed has 600,000 followers.

In assembling the list, Forbes looked for women who run countries, big companies or influential nonprofits. Their rankings are a combination of two scores: visibility — by press mentions — and the size of the organization or country these women lead.

At No. 1, for the fourth consecutive year, is German Chancellor Angela Merkel. Up for re-election this September, she is leader of the world's fourth-largest economy. She faces a tough year: Germany's GDP is expected to shrink this year despite a small uptick in the second quarter.

Federal Deposit Insurance Corp. Chairman Sheila Bair, who remains in the No. 2 spot, has presided over the orderly takeover of 77 banks so far this year. In fighting for more power for her agency, she has butted heads with Fed Chairman Ben Bernanke and U.S.Treasury Secretary Timothy Geithner.

Chief Executives Indra Nooyi of PepsiCo (No. 3), Cynthia Carroll of Anglo American (No. 4) and Irene Rosenfeld of Kraft Foods (No. 6) rank among the world's most powerful businesswomen and are tasked with steering their companies through unusually challenging times.

Singapore's sovereign wealth fund, Tamasek, has delivered extraordinary average annual returns of 18% under the leadership of Ho Ching (No. 5). She is currently seeking a successor.

This year's list includes several notable newcomers — from the U.S. and abroad. The recently approved Supreme Court Justice Sonia Sotomayor debuts at No. 54. She will be the third woman and the first Hispanic in the top court. First lady Michelle Obama, a champion for working women and the families of the U.S. military, appears at No. 40.