The London whale was a UK-based trader called Bruno Iksil who worked for JPMorgan. He was known as the London whale among hedge funds and other traders, due to his big, and as it turned out, ill-advised position in a credit derivatives index.
The London whale in the news
In July 2012, JPMorgan announced losses of $5.8bn which it attributed to the London whale, who was also sometimes known as Voldemort. Iksil headed the credit desk in the London unit of JPMorgan's 400-strong chief investment office.
In October 2012 the bank issued a claim in London's High Court against Javier Martin-Artajo who supervised Iksil.
In January 2013 it emerged that Jes Staley, who had been head of JPMorgan's investment bank, although in a separate division to where Iksil was working, had crossed the divide to join BlueMountain Capital Management – one of the hedge funds that brought down the London whale.