Bank of New York Mellon Corp executed some currency transactions for two large public pension funds in a way that could trigger higher costs and boost its profit, the Wall Street Journal showed in an analysis.

The Journal examined currency trades conducted by BNY Mellon between January 2007 and May 2011 for the Massachusetts Pension Reserves Investment Management fund.

It also analyzed trades handled for the Los Angeles County Employees Retirement Association between May 2000 and September 2010.

The Journal analysis found the custodial bank at times separately executed trades when one client needed to buy and sell the same currencies on the same day, instead of matching the trades to offset each other in a single trade.

BNY reported separate purchases and sales of the currencies at the cost of $3.2 million to the Massachusetts fund when all or portions of 10,288 trades involving about $570 million worth of foreign-currency purchases could have been netted out at no cost, the Journal found.

In the past few months, BNY has been criticized regarding its foreign exchange operations for pension funds. The custodial bank recently said it would continue to defend itself.

For the Los Angeles fund, the Journal found that BNY charged $171,000 as cost of transaction for all or portions of 446 trades involving about $22 million worth of foreign-currency purchases that could have been netted out at no cost with sales of the same foreign currencies the fund made on the same days.

BNY was not available for comment outside business hours.