The document discusses the subprime mortgage crisis of the late 2000s. It defines prime and subprime loans, and explains that the crisis occurred when the housing bubble burst after many subprime borrowers defaulted on adjustable rate mortgages. This was caused by an overheated market where home prices increased too fast. When home prices started declining, foreclosure rates rose which further drove prices down. This created losses for many financial institutions and impacted the global economy. The US government responded by trying to help homeowners renegotiate loans to avoid foreclosure and providing liquidity to struggling financial institutions.