Bitcoin Exchange Accidentally Allowed Customers To Buy Coins For $0 (cnbc.com)
AmiMoJo writes: "A system glitch at cryptocurrency exchange site Zaif enabled users to obtain digital money for free, with one apparently "purchasing" Bitcoin valued at $20,000,000,000,000 and then attempting to cash in on it..." according to the Japanese newspaper Asahi Shimbun. "The glitch, which lasted for 18 minutes from 5:40 p.m. to 5:58 p.m. on Feb. 16, affected Zaif's price calculation system, enabling customers to buy cryptocurrencies for nothing."
CoinDesk adds that "At least one customer attempted to resell their bitcoin, but the large amount of the cryptocurrency offered soon drew attention even outside the exchange. The firm later cancelled the transactions and corrected the users' balances. However, a source suggests that the correction is still being agreed with one of the seven users who attempted to transfer the free bitcoin away from the Zaif platform."
CoinDesk adds that "At least one customer attempted to resell their bitcoin, but the large amount of the cryptocurrency offered soon drew attention even outside the exchange. The firm later cancelled the transactions and corrected the users' balances. However, a source suggests that the correction is still being agreed with one of the seven users who attempted to transfer the free bitcoin away from the Zaif platform."
There isn't even $20 trillion dollars worth of bitcoin in existence. You obviously wont be able to withdraw that to a real wallet. The bitcoin figure displayed on the website couldn't be backed by $20 trillion in real bitcoins.
The exchange seems to have been screwed over by one customer withdrawing some of the bitcoin of the exchange, obviously not $20 trillion. But it seems some amount of real bitcoin was withdrawn.