rogue trader
noun [ C ] uk/ˌrəʊɡ ˈtreɪ.dər/ us/ˌroʊɡ ˈtreɪ.dɚ/
（因投资失败或非法投资而使委托人蒙受巨大损失的）恶棍证券股票经纪人
a stockbroker (= someone who buys and sells shares for other people) who secretly loses a large amount of their employer's money after making a bad or illegal investment