The US is looking into whether the world's biggest banks have rigged the prices of precious metals such as gold, silver and platinum.
The Department of Justice (DoJ) and Commodities and Futures Trading Commission (CFTC) have launched the investigation following of a series of scandals in which banks altered benchmark rates to make financial gains for themselves, namely libor and the foreign exchange rate.
According to the Wall Street Journal, at least 10 banks will be looked into as part of the investigation, including HSBC, Barclays, Goldman Sachs and Deutsche Bank.
Until recently, benchmark prices for precious metals were set during a telephone conference call between a group of banks. Last year this practice was scrapped and the prices are now set electronically, which means the investigation is likely to concentrate on practices before the reform was made.
The UK's own financial watchdog, the Financial Conduct Authority (FCA), has chosen not to launch a separate investigation into the rigging of precious metal prices.