Total Return Index

Discussion in 'SP5' started by dgw201, Mar 10, 2012.

  1. dgw201

    dgw201 Member

    Hello

    I'm slightly confused about the assumption of reinvestment of dividends back into the index for TRI.

    The 1st formula given by Acted: TR = I(t) - I(t-1) + XD(t) - XD(t-1)/ I(t-1)
    Does not seem to include this assumption, as we're effectively just adding two returns together.

    The second formula given in the core reading does seem to include the assumption: TRI(t) = TRI(t-1) * I(t)/(I(t-1) - [XD(t) - XD(t-1)])

    So my point is - should we only be using the second formula given in the core reading if we state this assumption?

    Thanks
     
  2. Colin McKee

    Colin McKee ActEd Tutor Staff Member

    Formulae for returns

    Hi, The most likely formula to use in ST5 will be the first version. The one with the (XD2 - XD1) on the top line. This would be used to calculate the total return over a week, or a month, or a year. However if you are making a total return index, which requires reinvesting income back into the index on a daily basis, you would use the second formula. Apparently its better in this one set of circumstances. I can only think of one question in ST5 where the second frmula has been used, but I can think of loads that use the first formula. Hope this help.
     

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