“The purpose was to try to make more money trading,” Christopher Cummins testified Friday in Manhattan federal court. “I was supposed to be pricing on my own. I was supposed to be competing.”

Cummins, 53, was one of the first traders to admit wrongdoing in a US criminal investigation of price-fixing in the currency markets.

He’s testifying for the government in the trial of former JPMorgan Chase & Co. trader Akshay Aiyer, who’s charged with taking part in the rigging of African, European and Middle Eastern currencies.

The charges stem from a multiyear probe by the Justice Department’s antitrust division. Banks have paid more than US$10 billion in penalties for currency-market abuse.

Joceyln Sher, Aiyer’s lawyer, said on Thursday that the government’s case is based on “highly flawed and seriously compromised witnesses” who are implicating Aiyer to win a break from prosecutors. What Aiyer did wasn’t a crime, she argued.

Cummins worked for Citigroup from 1992 until he left in April 2014. He pleaded guilty to conspiring to fix prices in January 2017, a week after former Barclays trader Jason Katz, who is also slated to testify for prosecutors against Aiyer.

Aiyer, 36, is a native of India who came to the US in 2002 to attend college. He joined JPMorgan in 2006 and worked there until 2015, first as a foreign-exchange analyst and later as a trader.

Indicted last year on a single count of conspiracy, he faces as long as 10 years in prison and a US$1 million fine if convicted.

Prosecutors have had mixed results in currency-rigging trials. Former HSBC Holdings Plc trader Mark Johnson was convicted in 2017 of front-running a US$3.5 billion client order, but a federal jury in New York last year acquitted three British traders accused of similar conduct.

UK investigators dropped a criminal probe of individual FX traders, finding there wasn’t enough evidence to prosecute.

The case is US v. Aiyer, 18-cr-333, US District Court, Southern District of New York (Manhattan).