Geithner's appointment calendar from 2009 detailed his extensive contacts with CEOs of Goldman Sachs, JPMorgan Chase and Citigroup.
Since leaving office, Geithner signed a deal with Random House's Crown Publishers to write a behind-the-scenes book about the response to the economic crisis and has given speeches.
Geithner has spent most of his career in government, although he had an early stint at Kissinger Associates, the consulting firm formed by former Secretary of State Henry Kissinger. Geithner joined the Treasury Department in 1988 and served as undersecretary for international affairs during the Clinton administration. He worked at the International Monetary Fund from 2001 until 2003 before being named president of the New York Fed.
Private equity firms pool money from clients such as pension funds and other institutional investors to buy companies or stakes in companies. They try to improve the financial results of a company with the goal of reselling it at a profit.