I owe this one to Mario Gabelli who recently spoke to Tom Keene from Bloomberg. While speaking with Tom, Mario mentioned that every politician should read M & T Bank's 2010 Annual Report. He referred to the section titled "Regulation and The State of The Banking Industry." This is a wonderful read highlighting many changes that have occurred in the banking industry over the last 80 years. Below is a link to the whole Annual Report, the banking industry section starts on PDF page 15.
This explanation is worth so much, defining systemic risk, M&T CEO Wilmers says, "the aggregation of risks in the hands of so few has the potential to impact the fortunes of so many." What a great way of explaining a concept that has been thrown around so much and never explained in the most general sense.