A detailed new case study scrutinizing the risk-management Swiss-based Trafigura is the latest effort to "demystify" the once-secretive commodity trading industry, just big merchants seek to fill a void being left by Wall Street banks. The study, "The Economics of Commodity Trading Firms," comes as U.S. regulators mull new restrictions on banks' physical commodity trading, a crackdown some large energy companies say would rob them of credit-worthy, transparent counterparties and leave them at the mercy of shadowy and risky firms.