"We have previously communicated the fact that most clients’ crypto-asset funds are stored in multi-signature cold wallets. However, the malicious external party involved in this breach, managed to alter our system so that ETH and BTC deposit transfers by-passed the multi-sig cold storage and went directly to the hot wallet during the breach period. This means that losses of ETH funds exceed the 5% limit that we imposed on our hot wallets.
Loss of Funds

In total, the hot wallet breach resulted in the loss of ETH 185,000 and BTC 250, which is equivalent to USD 2 million. This represents 15% of total crypto-asset deposits held by Gatecoin." -- https://gatecoin.com/