Macaulay / Duration flat or increasing yield curve

  • In an upward-sloping yield curve, portfolio duration and IRR will be higher-than-average duration and YTM of the bonds because portfolio statistics reflect all cash flows (and return) to be received and the longer maturity bonds will impact the portfolio for a longer time.

I tried to model a simple portfolio one two bonds. However I do not reach the same conclusion? Am I missing something. I do find that the YTM of a a steeper yc will be higher. However Duration / MacD. appear the same