As and when trades are conducted, share prices change. This is because prices of shares – like any other goods – are dependent on the perceived value. This is reflected in the rise or fall of demand for the stock. As demand for the stock increases, there are more buy orders. This leads to an increase in the price of the stock. So when you see the price of a stock rise, even if it is marginal, it means that someone or many persons placed buy order(s) for the stock. Larger the volume of trade, greater the fluctuation in the stock’s price. Typically, mid cap and small cap stocks tend to be more volatile than large-cap stocks.