U.S. prosecutors are pressing to bring charges against a bank for currency-rate rigging by the end of the year, and actions against individuals will probably follow in 2015, according to people familiar with the probe.

The Justice Department may seek guilty pleas from several firms, including at least one in the U.S., said one of the people, asking not to be named because details of the investigation aren't public. While federal prosecutors have wrested convictions from foreign banks this year for wrongdoing, they've yet to win a guilty plea from a U.S. lender in that push, and they're preparing for strong resistance if they attempt to do so.

Justice Department officials have vowed to hold more institutions and individuals accountable for criminal conduct amid public frustration over the lack of prosecutions against top Wall Street executives for the worst financial crisis since the Great Depression.