NEW YORK (Reuters) - A former Deutsche Bank AG <DBKGn.DE> trader pleaded not guilty on Thursday to U.S. charges that he conspired to manipulate Libor, the benchmark interest rate at the center of global investigations into misconduct at various banks.

Gavin Black, 46, a former director on Deutsche Bank's money market derivatives and pool trading desks in London, entered his plea in federal court in Manhattan to conspiracy and wire fraud charges after waiving extradition from Britain.

Black was indicted in June along with Matthew Connolly, formerly Deutsche Bank's director of the pool trading desk in New York, becoming one of four onetime employees at the bank to be charged by the U.S. Department of Justice.

Libor is based on what banks say they believe they would pay if they borrowed from other banks. The rate underpins trillions of dollars of financial products globally from mortgages to credit card loans.

U.S. and European authorities have been investigating whether banks attempted to manipulate the rate to benefit their own trading positions.

Those investigations have resulted in about $9 billion in sanctions worldwide against financial institutions and 16 people being charged by the Justice Department. In 2015 Deutsche Bank agreed to pay $2.5 billion to resolve related U.S. and U.K. probes.

According to the indictment, from 2004 to 2011, Connolly and Black and other Deutsche Bank employees engaged in a scheme to manipulate Libor, which was tied to the profitability of derivative trades in which the bank had a financial interest.

Prosecutors said eight other Deutsche Bank employees were involved in the scheme, including former traders Timothy Parietti and Michael Curtler, both of whom have pleaded guilty and are cooperating with authorities.

Connolly, a resident of Basking Ridge, New Jersey, has pleaded not guilty.

The case is U.S. v. Connolly et al, U.S. District Court, Southern District of New York, No. 16-cr-370.

(Reporting by Brendan Pierson and Nate Raymond in New York; Editing by Chizu Nomiyama and Bill Trott)