Coupon Paying bonds are essentially portfolios of Zero Coupon Bond components and the Yield to Maturity of such instruments can be thought of as being a complex blend of the component Zero Coupon bond yields. It therefore can be observed that, for example, in a positively sloped Yield Curve environment and comparing two bonds with the same cash flow dates and maturity, a higher coupon bond will offer a lower YTM than a low coupon bond - assuming the same PV calculated from the same discount curve. (The low coupon bond has cash flows more heavily influenced by a proportionally greater long term component).