Specialists do move the market. The specialist is paid for each 100sh they move. If they can move the price into an area of with a high density of stop orders the orders will trigger and they make money. The specialist is one of the few who know exactly where those stop orders lie. Usually it is just above the prior high or just below the prior low.
) be gapped by moves in Europe. a typical scenario might be post-close US news which is moderately bullish but when Europe opens the follow through just isn't there and the stocks that were supposed to be up in sympathy with the US news start to get sold off hard...so that when the US wakes up the bullish news has led to a gap down seemingly from nowhere...