The 3 Most Timeless Investment Principles (3 of 3) The Age of a Mutual Fund

The Advantages and Disadvantages of a Stop-Loss Order

The advantage of a stop order is you don't have to monitor on a daily basis how a stock is performing. This is especially handy when you are on vacation or in a situation that prevents you from watching your stocks for an extended period of time. The disadvantage is that the stop price could be activated by a short-term fluctuation in a stock's price. The key is picking a stop-loss percentage that allows a stock to fluctuate day to day while preventing as much downside risk as possible. Setting a 5% stop loss on a stock that has a history of fluctuating 10% or more in a week is not the best strategy. You'll most likely just lose money on the commissions generated from the execution of your stop-loss orders.
Source: http://www.investopedia.com/articles/stocks/09/use-stop-loss.asp