Goldman Sachs Group got into the residential mortgage business in 1984, and for 17 years, it ran a staid operation that simply bought and sold loans.

All that changed in 2001, when the elite investment bank leaped aggressively into the burgeoning subprime securities market that was becoming a fountain of money for its Wall Street rivals. The Goldman Sachs Mortgage Co. sold $8.7 billion in subprime bonds that year, amounting to a third of its business.

Soon, the Goldman subsidiary was in the jet stream, dealing with some of the most aggressive and controversial subprime lenders — including Ameriquest (through a subsidiary), New Century, Fremont General, National City and First Franklin.