What can make stock prices rise or fall?

There are many reason for prices to rise and fall. I often consider the stops above and or below the market before entering a trade or new position.

i.e. A trader buys a stock the first thing he does is place a stop loss just below the last pivot low. The second thing he does is either put his target a million miles in dream land or tells himself hes going to hold on until he sees a definite reason to exit.
What has happened here ? The trader that has all the confidence in the world of a stock rising has put a negative on that stock when it finally hits his stop he will sell out at the lowest price seen in weeks and all his fellow traders who have their stop there help him to drive down the price of the stock.
Or the reverse could be true.
A trader believes a stock is ready to collapse. He sells the stock short and puts a buy stop just above the market. He dreams about making his fortune on this very trade and retiring to the gold coast, so decides to not place a target and just let the money flood the trading account till it overflows. The market wanders around then a quick spike gets him buying the stock at new highs.

My opinion is higher prices beget higher prices and lower prices beget lower prices. If you enter a trade a Target and a Stop should be your first concern. If you only place a stop you are saying that you will only take a small profit or a loss. Have a target in mind and when the price gets there dont move it. You should even consider reducing any target by a little bit to allow for error. Book that profit and move onto your next trade.

My opinion only. Raef