Mtgox has announced they're indeed reversing the transactions. https://support.mtgox.com/entries/20208066-huge-bitcoin-sell-off-due-to-a-compromised-account-rol

Mtgox has announced they're indeed reversing the transactions. https://support.mtgox.com/entries/20208066-huge-bitcoin-sell-off-due-to-a-compromised-account-rollback https://support.mtgox.com/entries/20208066-huge-bitcoin-sell... Presumably they can do this because they're not actually bitcoin transactions, just exchange trades. The bitcoins and USDs entering and leaving Mtgox are not going to roll back.