Treasury Secretary Timothy Geithner...

....oversaw the largest increase in the national debt of any Treasury secretary in American history, presiding over a $3.7 trillion increase in the debt. According to data from the Treasury Department's Bureau of the Public Debt, the national debt has increased $3,723,575,990,130.10 from Jan. 26, 2009 until June 30, 2011, Geithner's entire tenure to date as Treasury secretary. When Geithner took office the total national debt stood at $10.6 trillion. As of June 30, 2011, it had risen to $14.3 trillion