Javier Martin-Artajo, the former JPMorgan Chase & Co. trader accused by the U.S. of helping to hide trading losses that surpassed $6.2 billion, told a Spanish judge he didn’t want to be extradited.

Martin-Artajo told Judge Santiago Pedraz that he didn’t wish Spanish authorities to hand him over to the U.S. when he answered a summons to appear at the National Court in Madrid. A court official, who asked not to be named in line with policy, briefed reporters on proceedings at the court.

The Spanish citizen, who oversaw synthetic credit trading at JPMorgan’s chief investment office in London, was indicted in the U.S. in September for engaging in a securities fraud to hide losses stemming from trades by Bruno Iksil, the Frenchman at the center of the case who became known as the London Whale. Martin-Artajo turned himself in to police in Madrid in August. He was released pending the handover of extradition papers that reached Judge Pedraz last month, after Spain’s cabinet ruled the case could proceed to court.