German Chancellor Angela Merkel of the Christian Democratic Union (CDU) delivers her speech during an election campaign rally in Bremen August 17, 2009. Merkel tops the first on the newly-released Forbes 100 Most Powerful Women. [Agencies]

US first lady Michelle Obama is among the world's 100 most powerful women in a list topped for the fourth consecutive year by German Chancellor Angela Merkel, according to a Forbes ranking released on Wednesday.

Obama debuted at No. 40, coming in ahead of talk show host Oprah Winfrey at 41 and Britain's Queen Elizabeth at 42.

Sheila Bair, chair of the U.S. Federal Deposit Insurance Corp., which insures bank deposits, retained the No. 2 spot after debuting on the Forbes list last year. She has gained increased prominence as the US recession grinds on.

Federal Deposit Insurance Corporation Chairwoman Sheila Bair speaks during her testimony at the Senate Banking Committee on Capitol Hill in Washington July 23, 2009. Bair is ranked the second on the newly-released Forbes 100 Most Powerful Women.

The chief executives of PepsiCo, Anglo American, Temasek, Kraft Foods, WellPoint, and Areva all remain in the Forbes top 10.

The list is based on factors such as economic impact, media reach and career accomplishments.

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

This year's list includes several notable newcomers - from the US 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 US military, appears at No. 40.

The chief executives of Dupont and Sunoco are new to the top 10, replacing the Xerox Corp. chair, who dropped to No. 15, and former U.S. Secretary of State Condoleezza Rice, who fell off the list after leaving office in January.

Rice's successor, Hillary Clinton, came in at No. 36, dropping from No. 28 last year when her presidential bid made her the woman with the highest public profile on the list.

Nancy Pelosi, speaker of the U.S. House of Representatives, retained No. 35.

"Women in power are rising to leadership positions in business, government and philanthropy by making daring and unconventional moves," Forbes said. "Gone are the days of women feeling they must stick with one employer and patiently wait for promotions."

"Highly ambitious women ... are moving across companies and industries, making big leaps with each change, and repositioning themselves for opportunities that allow them to gain a breadth of experience," the business magazine said.

Merkel, 55, became the first female chancellor of Germany in 2005 and is widely expected to retain power in a federal election on September 27.

Obama, 45, has won fans for her down-to-earth personality, her support of causes including healthy eating and the arts, and her fashion sense that has seen her grace several best-dressed lists.

Other U.S. newcomers include Supreme Court Justice Sonia Sotomayor at No. 54, Secretary of Health and Human Services Kathleen Sebelius at No. 56, Secretary of Homeland Security Janet Napolitano at No. 51 and Securities and Exchange Commission Chair Mary Schapiro at No. 55.

Also new to the list are Prime Minister of Bangladesh Hasina Wajed at No. 78, U.N. High Commissioner for Human Rights Navanethem Pillay at No. 63 and Icelandic Prime Minister Johanna Sigurdardottir at No. 74.

Chairman and CEO of PepsiCo Inc. Indra Nooyi speaks at a panel discussion "Wellness in the Workplace: Obesity and Other Bottom-Line Issues" at the 2009 Milken Institute Global Conference in Beverly Hills,California April 27, 2009. She is the third on the newly-released Forbes 100 Most Powerful Women.

Ho Ching, Temasek Holdings executive director and CEO, laughs as she listens to Institute of Policy Studies (IPS) Chairman Tommy Koh (R) speak during an IPS Corporate Associate lunch in Singapore July 29, 2009. Ho is the fifth on the newly-released Forbes 100 Most Powerful Women.

Kraft Foods Inc CEO Irene Rosenfeld speaks at the company's headquarters during the launch of their new corporate logo, in Northfield, Illinois, February 10, 2009. Rosenfeld is the sixth on the newly-released Forbes 100 Most Powerful Women.

This Jan. 12, 2009 file photo provided by Yahoo, shows Yahoo CEO Carol Bartz at the company's headquarters in Sunnyvale, Calif. Bartz is ranked No.12 on the newly-released Forbes 100 Most Powerful Women.

U.S. President Barack Obama (L) applauds new Supreme Court Associate Justice Sonia Sotomayor during a reception in the East Room of the White House in Washington August 12, 2009. Sotomayor debuts on the newly-released Forbes 100 Most Powerful Women as No.54.

U.S. first lady Michelle Obama and President Barack Obama enjoy a country music performance at the White House in Washington July 21, 2009. Obama appears at No. 40 on the newly-released Forbes 100 Most Powerful Women.

U.S. Secretary of State Hillary Clinton speaks to the media during a visit to the Foreign Minister's Residence in Abuja August 12, 2009.

U.S. Speaker of the House Nancy Pelosi gestures during a news conference on the American Affordable Health Choices Act on Capitol Hill in Washington July 22, 2009.

Iceland's Prime Minister Johanna Sigurdardottir answers questions at a news conference with foreign news media in Reykjavik April 25, 2009. Obama appears at No.74 on the newly-released Forbes 100 Most Powerful Women.