Merrill Lynch & Co.'s Irish unit was fined $4.14 million by the country's financial watchdog after it found that traders failed to appropriately value their positions on transactions that lost the company $461 million.
The trades occurred in the company's London office.
The Irish Financial Services Regulatory Authority said the breaches happened because Merrill Lynch, the securities unit of Bank of America Corp., failed to supervise the traders and had an "inadequate month-end independent price-verification process."