As if JPMorgan Chase & Co. investors didn’t have enough to worry about with the $13-plus billion settlement with the U.S. Justice Department looming over the company. Now, JPMorgan Chase and Citigroup Inc. have put a number of their currency dealers on leave ahead of a new regulatory investigation into foreign exchange-rate manipulation. Specifically, regulators are looking into three individuals’ use of an instant messaging service over the last three years to communicate exchange-rate information. While no wrongdoing has been found at present, the regulators are looking into whether these people were trying to manipulate exchange rates in this $5.3 trillion-a-day business. Should they find evidence of malfeasance, shares of these banking giants could be punished.