I'm not sure what to make of this, and I would be grateful to hear what others think. I noticed recently something about FIREcalc: the historical rate of success for my retirement plan changes with the current fluctuations of the market. In my case, the changes have been small, but let me give a hypothetical example to illustrate... suppose one day you have 1M invested in the stock market. You enter that into the tool and see that the historical rate of success with a certain WR is 95%. The next day the market tanks. You now have only 700,000 in your portfolio. You enter that information into the tool, and all of a sudden the historical rate of success has dropped from 95% to a mere 65%. Which rate should you use for planning? Is it reasonable to say that even though the success rate has fallen, it is actually higher than indicated because your portfolio started at a higher value and once had a higher success rate? Or is that just wishful thinking? By the same token, should you then downward adjust your expectations if the success rate was lower recently and has surged with a run-up in stock values?