Which 2011 event caused a sharp global market sell-off after the United States lost its AAA credit rating?

The 2011 event that caused a sharp global market sell-off after the United States lost its AAA credit rating was the 2011 United States debt-ceiling crisis.

The crisis developed during a political dispute over raising the federal debt ceiling. Without an agreement, the U.S. government risked being unable to meet all of its obligations. Congress passed the Budget Control Act on August 2, 2011, shortly before the Treasury’s projected deadline.

On August 5, Standard & Poor’s downgraded the United States from AAA to AA+, citing political and fiscal concerns. Global equities fell sharply, while investors moved toward assets viewed as safer. The downgrade did not produce an immediate U.S. Treasury default, and other major credit agencies retained top ratings.

The event is distinct from the 2008 financial crisis and from later government shutdown disputes. Its central issue was the statutory borrowing limit and political uncertainty surrounding it.