So now we can look at what the markets have actually done in the five years since I shared that forecast (not prediction) in the orange squiggly line in the following graph:
You can see that SP500 varied about my crude bast fit (the middle, or "median" projection), fluctuating both above and below to touch what I called the 90th and 10th percentile bounds, never (so far) having reached the absolute worst possible (based on past fluctuations, not necessarily impossible to go lower) or best possible bounds. Note that my "worst possible" lower bound projection is at around 1500, what Igy had been confident for some time to be a probable case.
As it happens, the markets are currently hovering at pretty close to my crude best fit projection, suggesting that they are currently equally likely to drop above or below the median projection in the near and medium term. I will note, though, that my original crude best fit was an exponential curve. One might argue (and I'd be inclined to believe) that a power law is a more natural representation of the phenomenon. This graph shows both power law and exponential best fits from 1950 to today:
If I normalize actual index values to both best fits by dividing index value by the best fit curve values over time, I can see these curves for the power law and exponential best fits, in turn:
A value of 1 in either curve suggests that the markets are at the mean long term best fit (i.e., at "the mean"). Values above 1 suggest the markets need to drop to revert to (or swing past) the mean, and values below 1 suggest markets would need to (eventually) increase to get back to "the mean." The power law best fit is well above 1, at about 1.45 (i.e., 45% above the best fit), whereas the exponential curve shows the markets at 1.04, or very close to the mean.
There's no way to know whether either of these "best fit" curves is more reasonable than the other (mathematicians might try to tell you differently). My own belief is that the SP500 is probably somewhat more likely to decline some more, possibly a lot, but maybe continue upward.
My best forecast, which I won't share graphically, is that by the end of 2025 (2.75 years from now, we see SP500 at ~ 4600 +/- 800.