Simple Reason : Follow me if some one hits the bid for 100 $ trade , then there is any easy explanation if the spread is 0.30x0.50 and some one hits the bid at 30 and someone buys on the offer thats is where you see the price swings, just means that very few are selling below the offer and someone could be trying to keep it down because maybe one of the people who wants to keep magnum down is playing these games because they are short the stock, and trust me I feel bad for anyone who is short :)