French bank Credit Agricole will probably reach a deal with US officials in the next two months to settle a probe of the bank's business in sanctioned countries including Iran, a source said.
A resolution is expected to follow a settlement with Commerzbank, which is in discussions with US authorities to pay about $650m (€500m) for breaking trade embargoes, the source added.
Credit Agricole's fine could be similar to Commerzbank's, according to the person.
A spokeswoman for Credit Agricole, declined to comment.
Shares in Credit Agricole, with a market value of about €30.9bn, fell as much as 0.7pc and was little changed at €11.99 in Paris. The Bloomberg Europe Banks and Financial Services Index rose 0.4pc.
Foreign banks have become increasingly eager to co-operate with US prosecutors after a heavy fine was levied against BNP Paribas SA in June. Despite requests for leniency from the highest levels of the French government, BNP had to pay about $9 billion and accept restrictions on certain activities.
Prosecutors linked the tough terms imposed to BNP's lack of co-operation.
At least three other European banks - Deutsche Bank, Societe Generale and UniCredit - are also being investigated for possible sanctions violations in various countries, according to company filings.
Credit Agricole Chief Executive Officer Jean-Paul Chifflet said last month that the bank was "entering a phase of explanations on the case with the authorities" after having conducted a "voluntary" internal review of certain dollar transactions between 2003 and 2008.
The investigations are being handled by the Justice Department, the Federal Reserve, the Manhattan District Attorney's Office and New York's Department of Financial Services. Spokesmen from those agencies declined to comment.