A credit crisis occurs when the availability of loans decreases or the cost of loans increases suddenly. It is often caused by a period of reckless lending that results in losses for lenders when borrowers default on loans. The 2007-2008 global financial crisis began as a subprime mortgage crisis in the United States, where heavy lending and defaults on housing loans starting in 2006 led to over $1.3 trillion in subprime mortgages outstanding by 2007. Major banks and financial institutions reported over $435 billion in losses by mid-2008. Central banks provided loans to increase liquidity as banks became unwilling or unable to lend, while governments announced bank rescue packages worth hundreds of billions of dollars.