A former executive of Boston-based State Street Corporation pleaded guilty to conspiring to defraud at least six of the bank’s clients through secret commissions applied to billions of dollars of securities trades.

Acting Assistant Attorney General Kenneth A. Blanco of the Justice Department’s Criminal Division, Acting U.S. Attorney William D. Weinreb of the District of Massachusetts and Special Agent in Charge Harold M. Shaw of the FBI’s Boston Field Office made the announcement.

Edward Pennings, 46, of Surrey, England, pleaded guilty before U.S. District Judge Leo T. Sorokin of the District of Massachusetts to one count of conspiracy to commit securities fraud and wire fraud. Pennings is scheduled to be sentenced on December 11.

According to admissions made in connection with the guilty plea, Pennings, a former senior managing director of the bank and the head of its Portfolio Solutions Group for Europe, the Middle East and Africa, conspired to add secret commissions to fixed income and equity trades performed for at least six clients of the bank’s “transition management” business, which helps institutional clients move their investments between and among asset managers or liquidate large investment portfolios. The commissions were charged on top of fees the clients had agreed to pay the bank, and despite written instructions to the bank’s traders that generally reflected that the clients were not to be charged trading commissions.

In March 2016, Pennings was charged in a five-count indictment along with Ross McLellan, 45, of Hingham, Massachusetts. The charges against McLellan, a former executive vice president of State Street and president of its broker-dealer subsidiary in the U.S., remain pending.

The charges contained in an indictment are merely accusations, and all defendants are presumed innocent unless and until proven guilty beyond a reasonable doubt in a court of law.

The case is being prosecuted by Trial Attorney Aisling O’Shea of the Criminal Division’s Fraud Section and Economic Crimes Unit Chief Stephen E. Frank of the District of Massachusetts.