Ohio's attorney general on Monday sued Bank of New York Mellon for allegedly overcharging two state pension funds for currency trades, joining a growing group of regulators that have accused the custodial bank of profiting at its clients' expense.

Ohio Attorney General Mike DeWine's office said it had reviewed past currency transactions and found discrepancies between prevailing market rates and rates the Ohio Police & Fire Pension Fund and the School Employees Retirement System were usually charged. The funds are seeking more than $16m in damages for the alleged losses.