Bitladon buys and sells at different international markets. There is a market value, which you pay when you buy your coins, and a selling price, the price you get when you sell your currencies. Between those two there is a price spread. A price spread can vary from 0% up to more than 40%, depending on the coin. The price spread can even change per minute.
For example we'll take a look at Breakout (BRK). We do not purchase BRK for 0,06 euro, but 0,0000040 BTC or something like that. We can sell the BRK for 0,0000035. When you look at the numbers, it seems like the spread isn't that much, but it is almost 10%. This is the price spread between the market value en the selling price.
Apart from the spread, we have a standard fee of 2%. This fee is already taken into account. You can earn discount over this fee by trading. The more you trade, the more discount you will get. This can add up to 1,75%.