After a stock’s price has fallen can be a great time to buy (buy low) if you have done your research on the company. If all you know about a stock is the price, you may (and likely will) make investing mistakes. Remember, if a stock has had a good run up it may be time to sell, not buy (sell high). Similarly, if a stock has dropped like a rock, it may be a good time to buy rather than sell (buy low).