Yes we can not predict everything that happens in trading, especially with new altcoins. To minimize the risk we should only trade the potential altcoins such as ETH, BTC, XEM, XRP.
It really different way on how you trade when you're trading stock exchange and trading with altcoin.
Both of them are have their own risk but stock trading usually depend on world issue meanwhile about altcoin trading is really unpredictable if you're not fully analyze about it