IMHO - Investing 101: Fear, one of the two major driving forces in the market. The other is greed which makes the prices go up. The other significant forces are day traders and Market Makers (aka MM). The MMs control the trades when investors sell "at the market price" and don't use limit orders (hint - unless you're desperate, use limit orders to take the power away from the MMs). They can and do drive prices down with large block trades for their sell orders. Then they buy back for their buyers. Day traders buy/sell a stock multiple times in one day, making a few hundred bucks on each trade, playing the peaks and valleys. Short sellers thrive on bad news and sell borrowed stock and then buy back when the price is low. News is important(like last night's news), so pay attention to the news. Broader market activity (DOW, Nasdaq) also influences decision making. Lots of things to move the price up and down. Hope this helps.