HSBC also said the Justice Department sought documents related to the antitrust investigation in November. The two probes “are at an early stage,” the bank added, saying it is cooperating with U.S. regulators.

Also under scrutiny are Bank of Nova Scotia , Barclays PLC, Credit Suisse Group AG , Deutsche Bank AG , Goldman Sachs Group Inc., J.P. Morgan Chase & Co., Société Générale SA, Standard Bank Group Ltd. and UBS AG , according to one of the people close to the investigation.

The precious-metals probes are the latest example of regulatory scrutiny into how the world’s biggest financial institutions influence widely used benchmarks. Until last year, prices for gold, silver, platinum and palladium were set using a decades-old practice of once- or twice-a-day conference calls between a small group of banks. The process for setting each of the price “fixes” has since been overhauled.

Benchmarks for the four precious metals affect jewelry prices and financial products such as exchange-traded funds. U.S. commercial banks regulated by the Office of the Comptroller of the Currency had $115.1 billion of precious metals-related contracts outstanding as of Sept. 30.

Previously launched investigations of the interest-rate and foreign-currency markets have led to billions of dollars in settlements from major financial firms. Related probes are continuing in the U.S. and Europe, with additional cases against firms and individuals by the Justice Department expected in the coming months, according to people familiar with the matter.

More than 25 lawsuits have been filed against Barclays, Deutsche, HSBC, Bank of Nova Scotia and Société Générale over their alleged role in setting the gold fix. The plaintiffs are seeking damages for losses suffered due to the alleged manipulation of the price of the metal and gold derivatives. Law firm Berger & Montague, the court-appointed co-lead counsel for the proposed class-action suits, said the gold fix affected trillions of dollars worth of gold and related financial contracts.

Big Banks Face Scrutiny Over Pricing of Metals