One place and the only place where they make an absolute killing is on their trading desks.These trading desks are manned by hedgefund or glorified day traders who are backed up by "black boxes". Black boxes are computerized trading programs that spot stuff in the market and buy/sell accordingly at the blink of an eye - actually faster. Let me give you an example why, if you are in the market as a "buy and hold" type you are getting screwed faster than you can say bend over.
If you are on a trading floor chances are you get or subscribe to the S&P feed. That is a high speed "absolutely real time" commentary of the breaking news. If there is a shuttle launch, when you see it on CNN it is 5 seconds old. Almost EVERY traditional news source as a 5-7 second delay...so they can catch a naughty word or a mis-speak of consequence. 99.99% of us get our "news" on a delay. If you get the S&P feed, you get the news as fast as your IP address is connected. I get S&P. I saw the first 50 point dip yesterday 5 seconds before you did. I got my fat little finger on the sell button 5-7 seconds before you did. I made a killing while you cleaned up my mess. thank you by the way.
Citi does this in spades. They actually have black box software that can push that stampede by buying or selling "just before" the time delay. They make money and you get killed.
Have a nice day.