UK-based trader Navinder Singh Sarao vowed on Wednesday to fight US plans to extradite him in connection with alleged market manipulation that, authorities say, included a role in the so-called Flash Crash of May 2010.

Sarao appeared in court in London a day after he was arrested by British authorities. The futures trader, who was dressed in a yellow sweatshirt and white jogging pants, confirmed his date of birth and address, and said he didn't give consent to the extradition request.