There is more to it. This was a terribly bad idea.
As far as I can see it coinmarketcap only takes the last trade from dgex and the price it was traded for. Right now the price over there is 80% under starting value because someone traded 0,97 NXT for a ridiculous low price.
The data displayed is somewhere between bad and plain wrong
Being able to see the market capitalization of this coin gives utter transparency. If this information were not readily available the market would have a difficult time of determining what an appropriate price for 1 NxT should be. People would continuously be saying "NxT are too expensive" and "NxT are too cheap" based one their own subjective feelings. If you look at the list on coinmarketcap, NxT is one of two 2nd Generation Currencies (including Ripple for completeness) and it is scratching at the top 10. Does that make sense given it's enormous potential? Yes.
So the current price range for NxT is making sense and will only continue to make more sense as more people buy and sell - i.e. increased trading volume, which the increased exposure is going to generate anyway!
Coinmarketcap does the same thing for every cryptocurrency, it basically takes the last trade from he exchange with the highest volume and multiplies it by the total number of that coin in circulation. (It technically doesn't plot every point either, it probably grabs a new "last trade value" every 15 or 20 minutes.
Unfortunately NxT is so considerably different than most of the currencies on that list (1st Generation) that most comparisons we apply and predispositions we have are lacking. It is very much apples and oranges.
Also, another reason for the drop in the graph on coinmarketcap is that the only trade pair at the moment is NxT/BTC and the value of BTC has been dropping slightly.
Please spread less fud. There are mountains of information available to read about cryptocurrencies that have been generated in the past 4/5 years. Please read as much as you can about them to enlighten yourself.