For investments, the Holding Period Yield (HPY) or Holding Period Return (HPR) refers to the total return earned from an investment or an investment portfolio over the holding period, that is, the period for which the asset or portfolio was held by the investor.
Where Pt represents the time when the asset was purchased and Tt+1 is the price received at the time of sale of the asset. Income is any income earned from the asset such as interest.
In our T-bill example, the holding period return will be:
Note that for a T-bill there is no interest income since it is sold at a discount.