Simba:
ERROR FOR 85-06 CALCULATIONS:
Cell Z3 on sheet Returns_85_06 uses the following formula:
=Portfolio!$K$28
Cell AA3 on sheet Returns_85_06 uses the following formula:
=Portfolio!$K$30
It looks like Cell AA3 needs to use the formula =Portfolio!$K$29, and the remaining cells in the row need new transposed links.
ERROR CHECKING REQUEST
Also, if you can eliminate this error check in the calculations and instead use simple 100% summary visual sanity checks, that reduces rework for each rev to enable efficient frontier Excel Solver calculations. I have redone the Solver work twice now and it's been obsoleted a third time. I will not be supporting efficient frontier additions moving forward if we can't find a solution that will be incorporated or planned with compatibility in mind.
CHANGE PLANNING
Although I'm Pi Tau Sigma and Tau Beta Pi and enjoy mathematical acrobatics, simplicity is our friend until the basic portfolio options and datasets get nailed down. It will let us focus on data quality and basic calculation integrity. I think after the portfolio request additions and resulting structures settle down we should initiate discussions (and polls!) around metrics that are most useful to Diehards overall. I'm a little worried that as we add metrics into the tool, we may start to lose the forest for the trees.
Of course, I'm a guilty party in this process as well, shooting for the efficient frontier calcs too early

Portfolio Process Capability (Cp), Kurtosis, Monte Carlo analysis, discrete event simulations, and system dynamics models should all have their day in the sun, just maybe not yet (insert your "horse before the cart" jokes here).
Thanks for all the hard work Simba! This is the foundation for expansion work down the road.
Cheers,
Eric