there is no difference between price in US and Europe, unless one of the markets is closed, but as soon as it opens, even pre and aftermarket, it adjusts. The difference in % is 1. because of the change in parity (exchange rate) between euro and dollar, and 2. in us it starts fresh from 0% from opening, while in europe it shows the difference from previous day's close. (I might be wrong, but I don't think so about this second point)
It is a fight between option shorts and option longs. The option short sellers are trying to keep nok in a tight range so that the options they sold will expire worthless tomorrow. This tactic has been working so far though I suspect the smarter ones among them have already closed their position. The greedy last minute penny hunters are driving today's move.
Once this stock starts to move, it will be very quick because everyone will have to unwind their positions at once.