Investing in a bond for a period shorter than its Macaulay duration does not minimize interest rate risk and is not connected to the bond's yield-to-maturity. The investor may be more exposed to the changing bond prices due to interest rate variations.
When the investment horizon is shorter than the Macaulay duration of a bond, it does not necessarily indicate whether the bond is a good or poor investment. However, it suggests that interest rate risk is not minimized. Because Macaulay duration measures the average time it takes for an investor to be repaid the bond's price through its cash flows, investing for a period shorter than the duration may expose the investor to greater potential fluctuations in bond prices due to interest rate changes.
This can be of particular concern if the investor is forced to sell the bond before maturity, possibly incurring a loss if interest rates have risen (since bond prices and interest rates are inversely related). Nonetheless, having an investment horizon shorter than the bond's duration does not directly relate to the bond's yield-to-maturity, which is fixed at the time of bond purchase.