U.S. officials are investigating at least 10 major banks for possible rigging of precious-metals markets, even though European regulators dropped a similar probe after finding no evidence of wrongdoing, according to people close to the inquiries.

Prosecutors in the Justice Department’s antitrust division are scrutinizing the price-setting process for gold, silver, platinum and palladium in London, while the Commodity Futures Trading Commission has opened a civil investigation, these people said. The agencies have made initial requests for information, including a subpoena from the CFTC to HSBC Holdings PLC 5, +0.16% HSBC, -2.03% HSBA, -2.18% related to precious-metals trading, the bank said in its annual report Monday.