By John McCrank BOCA RATON, Florida (Reuters) – Cyber security is emerging as one of the biggest threats for exchange operators as hackers become more sophisticated in their efforts to disrupt the global financial system, a group of exchange leaders told an industry conference. More than half of the worlds exchanges were hit by cyber attacks in 2012, according to a paper released last year by the World Federation of Exchanges Office and the research department of the International Organization of Securities Commissions. We are worried a lot and we are far more worried now than we were just a couple of years ago, Magnus Bocker, chief executive of Singapore Exchange Ltd, said during a panel discussion at the Futures Industry Association conference in Boca Raton, Florida on Wednesday. Bocker said spending on cyber security is on the rise, but said exchanges need to do a better job of sharing information with each other on effective ways of combating cyber criminals.