A stock that has consistently given reward for the last two years may not give the same rewards for the next five years. Be careful to pick stocks that you understand or companies that you understand. See how or why they were able to give those returns earlier and check whether the conditions remain the same or are better, in which case repeat performance is always possible. However, be careful to notice any change in market conditions. For example some new innovative companies don’t have much competition but over a few years, begin to have competitors. See how strong the competitors are or not. There is no Money Back Guarantee in investments such as Stocks or Mutual Funds.