There are two ways to interpret this. This is good, or this is bad. It is good if this means banking industry is getting rid of bad Mofos and the deadwood. Or it could be completely opposite, this could be Rats running from soon to be sinking ship because they are on the inside and would know. http://www.activistpost.com/2012/03/worldwide-banking-resignations-triple.html
D-OH! Have you forgotten what year this is? They're resigning en masse, 'cause they want to enjoy their last few months on this Earth... 21 December 2012, my (wo)man! Are you gonna be there with me, at the end time, holding my hand?
Sarcastic as ever. If it is resgination then the answer is in the title. They are choosing to leave. So there is your answer. They are jumping ship or leaving due to pressure.
Bankers are getting a lot of pressure at the moment from the lack of returns they are making. Low interest rates and hard business conditions are making it harder to operate.