A British trader accused of triggering a £500 billion Wall Street crash boasted he could earn £1 million in a week in 'volatile' markets. Navinder Sarao, 36, made the bold claim in October last year in an email to business colleagues, which has been lodged in the Northern District Court of Illinois as evidence in any future trial against him. US prosecutors allege Sarao, who was arrested last week, helped to trigger the so-called 'Flash Crash' of Wall Street on May 6, 2010, from his parents' house in Hounslow, West London. Scroll down for video . US prosecutors allege Sarao, circled, helped to trigger the 'Flash Crash' of Wall Street on May 6, 2010 . The crash netted Sarao £27 million in profits, they claim. In an email to a company he set up in a Caribbean tax haven, Sarao asked for an urgent £4.25 million. He wrote: 'I tend to perform better when markets are volatile and this week alone I would have envisaged making at least £1 million.' Sarao appeared at Westminster Magistrates' Court on Wednesday and was bailed with a surety of £5 million. However, he has remained behind bars since his brief appearance, and remained there over the weekend after an official from the magistrates' court confirmed Friday it had not received the money.
Navinder Sarao, 36, made the bold claim in October last year in an email .
It was lodged in the Northern District Court of Illinois for any future trial .
US prosecutors allege he helped to trigger 2010 Wall Street 'Flash Crash'