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 '