Government regulation instituted as the result of the Great Depression kept the stock market in line. Score a big one for regulation. And that was a previous example of a collapse of capitalism. Greed needs boundaries. It's human nature.

Hedge funds and derivatives were created in part as an end-run around the margin and other requirements which kept raw greed from destroying the stock markets.

Perhaps you could explain how a highly leveraged derivative, one with say 10% down and the other 90% being supplied by a bank through funds from a Central Bank, contributes to productivity, jobs, and the general welfare and stability.

And why they shouldn't be regulated in order to prevent another collapse.

There were a lot of folks on the deregulation express. Only Bush, however, could have prevented the train from running off the tracks.