The 2000s United States housing bubble or house price boom or 2000s housing cycle was a sharp run up and subsequent collapse of house asset prices affecting over half of the U.S. states. In many regions a real estate bubble, it was the impetus for the subprime mortgage crisis. Housing prices peaked in early 2006, started to decline in 2006 and 2007, and reached new lows in 2011. On December 30, 2008, the Case–Shiller home price index reported the largest price drop in its history. The credit crisis resulting from the bursting of the housing bubble is an important cause of the Great Recession in the United States.
Increased foreclosure rates in 2006–2007 among U.S. homeowners led to a crisis in August 2008 for the subprime, Alt-A, collateralized debt obligation (CDO), mortgage, credit, hedge fund, and foreign bank markets. In October 2007, Henry Paulson, the U.S. Secretary of the Treasury, called the bursting housing bubble "the most significant risk to our economy".