Why haven't I ever heard about this ?
http://www.coindesk.com/poloniex-loses-12-3-bitcoins-latest-bitcoin-exchange-hack/The hacker discovered that if you place several withdrawals all in practically the same instant, they will get processed at more or less the same time. This will result in a negative balance, but valid insertions into the database, which then get picked up by the withdrawal daemon. ~ D'Agosta
If I did not make this adjustment, people would most likely withdraw all their BTC as soon as possible in order to make sure they weren't left in that remaining 12.3%.
Does anyone else notice the same "oh noes how did that happen ??!! I'm a stupid noob and/or I got hacked" narrative ?
If I am not mistaken, Poloniex quite swiftly paid back the "12.3%" via exchange fees.
Don't quote me though, as I am not positive.
Remember hearing about it ages ago.
Let's try to stay on topic.