XEM(NEM) is a large market cap alt coin that recently had $530 Mln worth of XEM stolen from a low security hot wallet on a large Japanese exchange named Coincheck. This has caused a lot of FUD in the crypto community regarding XEM but what some people don't realize is that this has nothing to do with NEM's blockchain it was a security problem with the exchange. Thankfully though the XEM developers have put security in place that has tagged the stolen funds making it hard for the hackers to dump their stolen funds on the market. If they try to exchange the stolen crypto for Bitcoin, or altcoins the exchanges will be alerted that tainted funds are being used.
https://twitter.com/Inside_NEM/status/956964401399156736
- Inside_NEM
Any bad news towards a cryptocurrency though seems like enough of a reason for weak hands to sell their bags causing a chain reaction of sell orders/stop losses to trigger lowering the value of the currency.
Personally I'd just HODL but if you want to sell me your XEM for cheap I'll take it.