A top U.S. Federal Reserve official on Monday suggested stress tests and certain capital requirements to contain the risks within the non-bank lending sector, while acknowledging there is little the central bank can do to impose such restrictions. Fed Vice Chairman Stanley Fischer offered a framework to more tightly regulate the lending activities of hedge funds, mutual funds and other non-bank entities – often referred to as shadow banks – though he was careful to show that he was offering suggestions and not potential central bank rules.