title: Looping through an investment strategy
body: <p>I've created an investment strategy that I would like to loop through for each starting date in the data set.  For example the first cell would be the future return if the strategy was started on 12/31/15, and the second cell would be the future return if the strategy was started on 1/1/16. As long as I can get an ending value I shouldn't have a problem getting the return in % terms. My code so far has not been successful. Below is the part of my code that is trying to accomplish this. I'm currently getting incorrect values for my future returns. </p>
  
  <pre><code>value = []
  for i in range(1,len(l)):
      df.loc[l[i], 'S&amp;P Future Return'] = sum(value) 
      for i in range(1,len(l)):
          value.append(df.loc[l[i], 'Returns']) 
  </code></pre>