IRR and MIRR revisited

As a consequence of senility, I feel I may not understand IRR and MIRR. Anway, I wrote up something here and here. The latter has a spreadsheet which compares IRR and MIRR. Click to enlarge. -------------------------------- One thing that really bugs me is the ongoing debate about reinvesting withdrawals. The argument (by some) is that IRR assumes that withdrawals from an investment portfolio are reinvested at the same IRR-rate. I never understood the argument ... so I wrote up my thoughts here. I could be wrong ... but those that say there's an implicit reinvestment assumption (when using IRR) never seem to justify that claim. Indeed, I reckon that somebody said it (long, long ago) and everybody now parrots the claim.