Japan's market was bombarded yeserday with $617 billion of erroneous stock orders in dozens of Asia's biggest corporations.
They were cancelled before they could be executed.
Over 40 requests to transact shares totalling 67.78 trillion yen ($617 billion) - greater than the size of Sweden’s economy - were cancelled in Tokyo before they could be matched.
This is according to data compiled by Bloomberg from the Japan Securities Dealers Association.
JSDA received an error report from a member and is still confirming what happened, according to an official.
The biggest order was for 1.96 billion shares of Toyota, or 57% of outstanding shares in the world’s biggest carmaker, for 12.68 trillion yen through an off-exchange transaction. Other stocks with cancellations included Honda, Canon, Sony and Nomura Holdings.
Mistakes, known on financial markets as a "fat finger error", occur periodically on the world’s electronic trading venues.
In 2009, UBS accidentally ordered 3 trillion yen of convertible bonds issued by Capcom. In 2005, Mizuho Financial Group's securities unit was unable to cancel a mistyped order for J-Com, costing the bank 27 billion yen at the time.
Orders to buy or sell stock are submitted and withdrawn all the time in electronic markets, where computerised strategies are used by traders to profit from price discrepancies and by market makers to anticipate demand.
But the sheer size of these latest Japanese cancellations took the traders by surprise.
One of the biggest American market makers, Knight Capital Group, was pushed to the brink of bankruptcy in August 2012 when its computers spewed mistaken orders on to US markets.
In that case, the orders found buyers and resulted in hundreds of millions of dollars in losses to the firm. The company was later bailed out and sold.
