This Vanity Fair piece explains a lot about AIG, AIG Financial Products and its role in the crisis. The whole thing’s worth a read, but this bit particularly caught my attention:

In June 2004 the Fed began to contract the money supply, and interest rates rose. In a normal economy, when interest rates rise, consumer borrowing falls—and in the normal end of the U.S. economy that happened: from June 2004 to June 2005 prime-mortgage lending fell by half. But in that same period subprime lending doubled—and then doubled again. In 2003 there had been a few tens of billions of dollars of subprime-mortgage loans. From June 2004 until June 2007, Wall Street underwrote $1.6 trillion of new subprime-mortgage loans and another $1.2 trillion of so-called Alt-A loans—loans which for some reason or another can be dicey, usually because the lender did not require the borrower to supply him with the information typically required before making a loan.