Getty Images/ Rob KimEach month, Jefferies CEO Rich Handler, also the head of its parent company, Leucadia, sends out a letter to his bankers, traders, and analysts with some words of encouragement. In the latest letter, Handler wrote about an off-site leadership program the firm held, where they were addressed by Clint Bruce, a retired US Navy SEAL officer and a former NFL player. Handler wrote that during Bruce's talk, they were taught the importance of thinking like a tribe as opposed to a team. "A team is a collection of people all working for a common goal.