Today, the world economy is in recession and the financial sector is experiencing a severe credit crisis. The origins of the credit crisis can be traced back to the subprime mortgage market in the U.S., where subprime refers to mortgagees who are unable to qualify for prime mortgage rates due to myriad reasons. These include past payment delinquencies, personal bankruptcies, low credit scores, large existing liabilities, or high loan to value ratios. As such, they represent a high-risk class of loan-borrowers with respect to defaulting on prospective payments.
In the last five years or more, a boom in subprime lending was fueled by, and it in turn propelled, a bull-run in the market for mortgage-backed securities. A Mortgage-backed security (MBS) is simply a merged pool of multiple mortgages that has a recurring stream of annuity payments associated with it over a horizon of 15 to 30 years. The annuity stream originates from the monthly mortgage payments that are purportedly expected from the corresponding loan borrowers. The lending boom sparked a spike in demand for homes, which in turn artificially inflated home prices and made investments in MBS assets very attractive for the banking sector. Banks consequently invested heavily in MBS assets, many of which had significant exposure to underlying subprime borrowers. They sought to neutralize the default risk to the associated annuity streams by investing in a form of insurance known as Credit Default Swaps (CDS). However, this turned out to be a superficial and temporary transfer of the underlying default risk. This is because of the high counterparty risk that was later realized in the overextended CDS market when subprime borrowers started to default en masse, and home foreclosures started to rise. Defaulting-led foreclosures in turn led to depressing home prices, particularly in subprime zip codes. These dynamics implied a significant downward pressure on the value of MBS assets as well as real physical home assets that ended up on the books of the banking sector through write-downs. A faster depreciation of assets relative to liabilities in turn put a downward pressure on the capital held by various banks.