Hello I dont understand I bought for 4000 Eur one hour ago of Ethereum when it was going up, it stayed around the 10-20%, it started to decrease 5 minutes ago so I sold it and now cex.io just gave me 3500eur for it... wtf... 
The %came from me watching livecoinwatch.. Cex.io doesnt have the accurate price ??
The %came from me watching livecoinwatch.. Cex.io doesnt have the accurate price ??
First thing you should look at is the rate on the exchange you are trading in. It may be significantly different than on all other exchanges.