I stumbled across the following article from the Heritage Foundation a moment ago:
Federalism and Financial Services
It's worth a quick read because it analyses how the Constitutional framework impacts the regulation of the financial services industry. It provides terrific background, but it's an ironic read since it argues in favor of repealing the Glass-Steagall Act, the depression era bill which separated the banking, securities and insurance businesses.
The act was indeed repealed, but that has been argued by many to have led to the careless financial moves that led to the current economic collapse. It's a bit like watching a train before the wreck.
