MF Global filed for Chapter 11 bankruptcy protection Monday morning, making the security firm possibly the U.S. casualty of the European debt crisis. Earlier in the morning, the firm, headed by former New Jersey governor and Goldman Sachs executive John Corzine, was suspended from conducting new business with the New York Federal Reserve. Under Corzine’s leadership, MF Global made risky bets on European sovereign debt. Louise Story, Wall Street and finance reporter for The New York Times, reports on the latest.