Have you seen the wall set up on Poloniex? Those usually mean that someone is trying to manipulate new unsuspecting investors.
This is not good for a serious project like NEM, NEM is not a P&D. It is looking for real utility, not short sighted profit.
NEM deserves more than simple P&Ds, it deserves a real place in the real world for people to use.
There are more and bigger walls on the sell side. 100btc at 1100. There has been a whale or whales "working" Nem on polo for a long time but there is usually a few in every coin. As regards NEM, they appear in times of low volume and pull the walls during high volume surges or falls.