The system was easy and fully monitored. These were the people monitoring it:
http://www.youtube.com/watch?v=_MGT_cSi7Rs" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
1) Freddie Fannie underwrote the subprime market, at the direction of Democrats mostly, a policy pursued for some 30 years.
2) Bush admin increased leverage limits on banks, although IIRC just to levels similar to Europe. Correct me if I'm wrong. In wide open daylight
3) Greenspan followed textbook central banking policy, eased interest rates during difficult economic events, EVERYBODY KNEW WHAT HE WAS DOING, NOT ONE SOUL COMPLAINED, IN WIDE OPEN DAY LIGHT.
4) Banks used swaps to hedge mortgage bets. This part, arguably the only possibly confusing or "non-transparent" part of all of this is not actually the root cause. When derivatives fail as hedges it's no different than when insurance companies fail to meet obligations after an unforeseen event. The fact of the matter is that any hedge or insurance plan can never conceivably cover all risk. It's not possible.
The root cause was creating this massive subprime market. Easy and transparent, nobody caught it, in fact at most levels it was encouraged by regulators. Rhap, you are calling for more regulators when your precious regulators are as much to blame as anyone, it's unbelievable. Banks have been repackaging notes for ages, nothing new or inherently dangerous there. Our best and brightest, Harvard Democrats on Wall Street, bet it all on red, and well it didn't land on red.