Stock prices keep varying from time to time due to market forces that are supply and demand. When there are many people willing to buy a stock than selling it, then ultimately the price goes up and the opposite- if more is willing to sell a stock than to buy it, hence higher supply than demand and leads to price to fall down.
The price of a stock reflects the current value of the firm and as an investor will it bring earnings? Most companies want to generate sales or earnings and this is one way that leads it making decision on how they are going to price their product.
Investor’s sentiments, attitudes and expectations can also affect stock price. Stock prices are volatile and unpredictable and varying response to adverse issuer, political, regulatory, market or economic development. For example on Monday’s stock prices go down more than any other day. Also it is said on December some stocks are a hot cake for is said to be a month of entertainment.