Bill & Melinda Gates Foundation is the largest private foundation in the world, founded by Bill and Melinda Gates. It was launched in 2000 and is said to be the largest transparently operated private foundation in the world. The primary aims of the foundation are, globally, to enhance healthcare and reduce extreme poverty, and in America, to expand educational opportunities and access to information technology. The foundation, based in Seattle, Washington, is controlled by its three trustees: Bill Gates, Melinda Gates and Warren Buffett. Other principal officers include Co-Chair William H. Gates, Sr. and Chief Executive Officer Susan Desmond-Hellmann.It had an endowment of US$44.3 billion. The scale of the foundation and the way it seeks to apply business techniques to giving makes it one of the leaders in venture philanthropy, though the foundation itself notes that the philanthropic role has limitations. In 2007, its founders were ranked as the second most generous philanthropists in America, and Warren Buffett the first. As of May 16, 2013, Bill Gates had donated US$28 billion to the foundation.