More on where the crisis started

Michael Flynn has more background on where the economic roots of the current crisis were planted:

Let's be clear: This is a Wall Street crisis, not a national economic crisis. The overall economy, while a bit weak, is still growing. Some politicians are comparing the current environment to the Great Depression. But in 1932, when the federal government last moved to bail out the banking sector, economic output had fallen 45 percent and unemployment was a staggering 24 percent. Today, economic output is actually up and unemployment is a historically modest 6.1 percent.

The overall economy doesn't even face a liquidity crisis in the current turmoil. Consumer, commercial/industrial, and real estate loans are all up over last year. Main Street is doing fine. The liquidity crisis is confined to Wall Street, between and among investment banks, insurance and securities firms, and hedge funds. There is the possibility that the contagion could spread, but in a global capital market, this is hardly certain.

As far as the origins are concerned, Mortgage-backed securities (MBSes) were the primary vehicle through which the damage was done, although they (like so many financial tools) are relatively neutral, but can be mis-used:

In the early years of this century, mortgage-backed securities exploded. Their growth provided unprecedented levels of capital in the mortgage market. There was a lot more money available to underwrite mortgages. At the same time, investment houses were looking to replace the healthy fees earned during the dot com bubble. MBSes had fat margins, so everyone jumped into the game.

[. . .]

Fannie and Freddie then went on a subprime bender. They made it clear that they wanted to buy all the subprime or Alt-A mortgages that they could find, eventually acquiring around $1 trillion of the paper. The market responded. In 2003 subprime mortgages made up less than 8 percent of all mortgages. By 2006, they were over 20 percent. Banks knew they could sell subprime products to Fannie and Freddie. Investments banks realized that if they laced ever increasing amounts of subprime mortgages into the MBSes, they could juice the returns and so earn bigger fees. The rating agencies, thinking they were simply dealing with traditional mortgages, didn't look under the hood.

Unfortunately, after several years of a housing boom, the available pool of households who could responsibly use the more exotic financing products had dried up. In short, there were no more people who traditionally qualified for even a subprime mortgage. However, Fannie and Freddie were still signaling that they wanted to buy these products. At the same time, activist groups were agitating for more lending to low-income families. Banks realized they could make even more exotic loan products (e.g., interest-only loans), get the activists off their backs, and immediately diffuse their risk by selling the mortgages into MBSes. After all, Fannie and Freddie would buy anything.

Everything worked as long as housing prices continued to rise. The most pessimistic scenarios on Wall Street showed a leveling off of housing prices; no one foresaw an actual decline in prices. Suddenly, though, there weren't enough buyers. In hot real estate markets, builders raced to bring inventory to market that they thought was inexhaustible. But at this point everyone (essentially) who could possibly qualify for a mortgage had received one. At the same time, the first wave of the more exotic mortgages began to falter. Interest rates on adjustable rate mortgages moved higher — the Fed was finally tightening the money flow — and mortgages that were initially interest-only were close to resetting, with monthly payments jumping to include principal. A not insignificant number of these mortgages moved into default and foreclosure.

It's a long article, but it really is worth while to read the whole thing.