Salomon Brothers was one of the largest investment banks in the US in the 1970s and 1980s. It was the first bank to sell mortgage-backed securities. The head of the government bond trading desk at Salomon had figured out a way to scam the Fed's treasury auctions. When the scam surfaced, the Fed and the SEC were both determined to bring down Salomon, but Warren Buffett stepped in to help find the culprit and keep the bank running.