Why does it seem like such a shock if JP Morgan has lost a few billions? When someone trades, they can win or lose, so the shareholders should be glad they have been on the right side most of the time.
As to the Libor Rate fixing by some of the staff at Barclays, if they are trading you assume they will play by the rules but sometimes for purposes of showing off their power, some of the staff do make deals which when caught out are not according to the rules. How can any one person, even a CEO, be aware of exactly what is going on with regards to each employee? It is a daunting task. It is to Bob Diamond's credit that he helped to bring back to profitability an ailing giant.
No-one of any integrity can condone the breaking of rules, which ensure fair play in the markets, but the concept that needs to be scrutinized is as to how much scrutiny can be done in real time, when people in dealing rooms make decisions that can sustain or break organisations or their customers.
That is my opinion anyway.