Former New Jersey Gov. Jon Corzine resigned as CEO of MF Global Friday, just days after the 230-year-old securities firm filed for bankruptcy protection, NBC New York reports. U.S. regulators are working to track down down more than $700 million in customer money that went missing after a disastrous bet on European debt. "I feel great sadness for what has transpired at MF Global and the impact it has had on the firm's clients, employees and many others," the former governor, senator and Goldman Sachs head said in a statement. On Wednesday, President Obama's re-election campaign said it would return donations made by the embattled CEO if he were charged with any wrongdoing, Reuters reports. MF Global's board confirmed Friday that Corzine is not seeking severance payments, an amount The Associated Press reports would be $12 million.