All the way back in 2007, an IT professional at HSBC hacked into the files of the bank's Swiss arm. Now, a coalition of investigative journalists have got their hands on the information that he took and are using it to expose the bank's efforts to help its wealthy customers hide cash and avoid taxes in their home countries.
The HSBC files, which cover the period 2005-2007, amount to the biggest banking leak in history, shedding light on some 30,000 accounts holding almost $120bn (£78bn) of assets.
The information stolen by Hervé Falciani proved that HSBC's Swiss branch was helping celebrities, international businessmen and even criminals stow cash in secret accounts where their various world governments couldn't find it. This help them avoid paying taxes and move money they earned through illegal activities.
The Swiss bank did everything from help "blood diamond" dealer Emmanuel Shallop open a secretive Dubai-based business account to help American surgeon Andrew Silva withdraw "bricks" of $100,000 that he sent back to America illegally. The bank also worked with drug dealers and helped countless other clients avoid paying taxes in their home countries.