£830,000,000 - Nick Leeson and the Fall of the House of Barings(1996)

25 Million Pounds details the collapse of Barings Bank in the mid 1990s primarily by a broker called Nick Leeson, who lost £827 million ($1.3 billion) by speculating on futures contracts. The film contextualises the downfall as the history of Barings Bank was one of the oldest and most prestigious merchant banks in Britain, run by the same family for decades with extensive ties to Britain's elites. But in the late 19th century Barings almost went bankrupt after investing heavily in South American bonds, including backing the construction of a sewer system in Buenos Aires. The bank was saved by The Bank of England, but Edward Baring, the head of the bank, was financially ruined and never recovered.