Regulators in the U.S., Britain and Switzerland ordered six banks to pay about $4.3 billion in the first wave of penalties since authorities began a global probe into the rigging of key foreign-exchange benchmarks last year.

The Office of Comptroller of the Currency fined Bank of America Corp. $250 million, while JPMorgan Chase & Co. and Citigroup Inc. will pay $350 million each, according to a statement. That adds to $3.3 billion of penalties announced earlier Wednesday by the U.S. Commodity Futures Trading Commission, Britain's Financial Conduct Authority and the Swiss Financial Market Supervisory Authority.

Banks and individuals could still face further penalties and litigation following the 13-month probe into allegations dealers at the biggest banks colluded with counterparts at other firms to rig benchmarks used by fund managers to determine what they pay for foreign currency. The Justice Department, which is working with the Federal Reserve, and Britain's Serious Fraud Office are still leading criminal probes into the $5.3 trillion- a-day currency market.