This discussion will focus on stocks. While the reasoning I will illustrate does apply to most investments, the discussion will focus on the effect on common stocks and their investors. Let’s look a two charts and try to decide which looks like the better investment:
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A quick look would have us saying chart #1 is the far superior investment. Here is the thing though, both charts are of Sears Holdings (SHLD). Chart #1 is SHLD since its inception and chart #2 is its chart for the past 3 months. Same investment and depending on your time frame, two very different results.
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Now, investor #2 has held the stock for 2 years now. He sat back and watched during the summer and fall of 2005 when the stock fell from $160 to $120. As he looked at the company he could see no fundamental reason for the dip. Nothing had changed with SHLD and the reasons he bought it were still valid. This being said he decided people were wrong for selling and bought more during this drop (many smart Berkshire Hathaway (BRKA) shareholders did the same during the tech bubble in the late 90's and have been richly rewarded). The stock has since rebounded and broke through the $160 level up to the near $180 it stands at today. Why was he so confident? He bought SHLD not as a trade but as an investment. He saw SHLD as an investment in Eddie Lampert. He saw increasing profitability in retail operations and a growing cash hoard for Lampert to invest. Based on the 16 year track record Eddie has, that cash is in excellent hands. During the summer of 2005 none of these parameters changed and in fact he had good company as Lampert was in the market buying the stock with him!! The only risks to his investment are a fundamental change in the company’s prospects (retail operations cease to be profitable) or Lampert leaving (unlikely since he owns 60% of the stock). In this investors mind, bad news or an “analyst” downgrade that causes the stock to dip are no big deal since it then allows him to buy more at cheaper prices. All of the risks that investor #1 has are meaningless to #2. They make no difference to the long term prospects of SHLD only the price the stock trades at today. If he plans on holding this investment until one of those fundamental factors changes, the weather this winter which is negatively effecting investor #1, will be meaningless to him.
The shorter your time frame of any investment, the increased risk you face that elements having nothing to do with the fundamentals of that investment will adversely effect the value of it. As you lengthen your time frame you diminish the importance of these short term events (risk).