Nick Leeson at Barings, Jerome Kerviel at Societe Generale, John Rusnak at Allied Irish Banks. And now the 31 year-old Kweku Adoboli, who allegedly ran up $2.3bn in losses at UBS. These are the rogue traders who have bought banks to their knees and global financial systems to a halt. In this short ebook, The Financial Times columnist John Gapper unlocks the mystery by delving into the risk-taking instincts of both humans and animals – from yellow-eyed junco sparrows in Arizona to honey-bees. A rogue trader is often an outsider who starts in a lowly role and gambles with a bank's money in a bid to become a star. Gapper traces patterns of behavior and personality that could be used to catch them before disaster strikes. But do the banks really want to? And are they just the symptoms of a financial system gone rogue?