Customers use ATM machines at a Mizuho bank branch in Tokyo,

JAPAN - DECEMBER 09: Customers use ATM machines at a Mizuho bank branch in Tokyo, Japan, Friday, December 9, 2005. Mizuho Financial Group Inc., Japan's second-biggest bank, said a typing error at its brokerage arm that triggered $3.5 billion of trades has cost the bank at least 27 billion yen ($225 million). (Photo by Andy Rain/Bloomberg via Getty Images)