German Chancellor Angela Merkel topped Forbes's list of the world's most powerful women for the fourth consecutive year, followed by US Federal Reserve Chair Janet Yellen, the magazine said Wednesday. Behind them came Melinda Gates, who co-chairs the Bill and Melinda Gates Foundation with her billionaire philanthropist husband, Brazilian President Dilma Rousseff and IMF chief Christine Lagarde. Hillary Clinton, former first lady, onetime Secretary of State and possible future US presidential contender, was listed at number six. The annual list includes women in business, media, politics, technology, entertainment, philanthropy and non-profits, billionaires, and finance, a new category for the first time. "As we mark the 10th anniversary of publishing the World's 100 Most Powerful Women list, these impressive women from around the world continue to make a dramatic, lasting impact on our global footprint and in all aspects of our lives," said Moira Forbes, president and publisher of ForbesWoman. Forbes has named Merkel the most powerful woman nine times. Top businesswomen on the list include General Motors CEO Mary Barra (No. 7) -- subject of the Forbes cover story -- Facebook COO Sheryl Sandberg (No. 9) and IBM CEO Virginia Rometty (No. 10). Forbes said the list features nine heads of state who run nations with a combined GDP of $11.1 trillion and 28 corporate CEOs who control $1.7 trillion in annual revenues. In another measure of influence, the 100 women on the 2014 list have a combined social media following of over 812 million, the magazine said.