It all started with, that yesterday morning in the computer system of the Stockholm Stock Exchange (Stockholm Stock Exchange) an unusually large lot for purchase appeared 4294967290 stock index futures. The stock index is calculated based on stock quotes 30 largest companies by capitalization. Each futures has a value of almost 107000 crown. In this way, the total cost of the lot is 459 561 500 030 000 crown, that is almost 460 trillion crowns! Lot price in 131 times the gross domestic product of Sweden.
Naturally, even theoretically, no seller could satisfy such an order. Trading on the stock exchange had to be temporarily stopped.
Most amazing of all, how did such an order get into the trading system at all?. Did someone have money in the amount of 131 times the national GDP?
Представитель Стокгольмской фондовой биржи выступил с пояснением, that in fact no client has placed such a lot for purchase, and its appearance in the trading system is explained by a technical error in the processing of numbers in the trading system.
Специалисты предложили объяснение, How could this happen. The fact, what figure 4294967290 did not appear by chance.
4294967290 = 2^32 – 6
In this way, if the system does not check the data type, then the request with a decimal value -6 she could perceive as an integer with a value 11111111111111111111111111111010 in binary. When converted to an unsigned integer, it turns out just 4294967290.
