Banks including Barclays, Deutsche Bank and Credit Suisse are planning to charge clients for carrying out foreign exchange trades at the so-called 4 pm fix, according to people familiar with the matter.

The fix, a key currencies benchmark, was a central focus of the recent investigation into alleged wrongdoing in the foreign exchange industry. The banks will start charging the fees after a new way of calculating the benchmark kicks in on Feb. 15, the people familiar with their plans said.