Bitfinex has announced (archive) that their hot wallet may have been compromised and in a move reminiscent of the Bitstamp hack earlier this year is asking customers to cease deposits to older addresses at this time. The full statement reads:

Dear Customer although we keep over 99.5% of users' BTC deposits in secure multisig wallets, the small remaining amount in coins in our hot wallet are theoretically vulnerable to attack. We believe that our hot wallet keys might have been compromised and ask that all of our customer cease depositing cryptocurrency to old deposits addresses. We are in the process of creating a new hot wallet and will advise within the next few hours. Although this incident is unfortunate, its scale is small and will be fully absorbed by the company. Thanks a lot for your patience and comprehension. Bitfinex Team

Update – So far 1,587 BTC is rumoured to have been stolen from Bitfinex and sent to an address of 17owg8RWb73qfE5HeQk6gg6RAgEUfxPXks. Bitfinex is yet to confirm or deny if any thefts occurred and if so, what amount was stolen from the hot wallet.