Right now Ethereum Classic is going through a bit of a security risk pickle. On 5 of January 2019, a deep chain reorgniaztion of the Ethereum classic blockchain was recognised.
On blockchain, the honesty of a certain amount of miners (over half) is required to ensure that any competing interests that aim to undermine the security of the blockchain cannot succeed.
Where a single miner has more resources than the rest of the network, they may be able to reorganise the blockchain for their own nefarious means. This makes it possible for double spend attacks to occur which is what we may be witnessing with Ethereum Classic at the moment.
Deep chain reorganisations were observed, some which involved double spending of hundreds of thousands of dollars.
One of the best ways of mitigating the risks of such an event is to temporarily freeze movements of funds on Ethereum Classic. That being said, blockchain is still a heck of a lot safer for many companies than non-blockchain platforms. A lot more than hundreds of thousands of dollars is lost per year by companies to fraud and cyber attacks.