"1.56 Price to Peak Book today per my calcs, expected 1 year forward return using Friday's closing share price, interpolated from the modeled returns: ~3.4%"

Reasonable expectation. Would you make any adjustments based on other factors? For example, do you adjust the expectation depending on whether P/B is rising or falling, or based on recent BV growth rate, or based on recent BRKB returns, or based on the broad stock market valuation, etc.?

Just considering one factor, whether P/B is rising or falling, does lead to different forecasts. I don't have the data for Berkshire in front of me, but I do have data for the S&P 500. The S&P 500 goes through long cycles of rising P/E and declining P/E (see Robert Shiller's graphs) with P/E not reverting to the mean, but rather cycling about the mean, which is different. Forward returns track the P/E (inversely), but along two different curves of return versus P/E. One curve, during periods of rising P/E, is concave upward, and another curve, during periods of falling P/E is concave downward. The two curves meet at the extremes of P/E, giving an overall return versus P/E graph that is football shaped. In the middle a P/E of 16 has a higher forward return when P/Es are rising and a lower forward return when P/Es are falling. Jim's averaging of a linear fit and a cubic fit for BRKB recognizes this, although he doesn't explain it in his post and may not agree with my explanation. He just observes that a linear fit is fat in the middle. If one thinks that Berkshire's P/B is now falling (after having risen from 1999 to 2022), then one might want to subtract a small amount from the 2025 expectation.

This is a bit esoteric. Just using the smoothed fit (third column) is perfectly fine. However I do tend to think that other factors besides P/B will affect Berkshire's return in 2025. In particular I am concerned about the return of the broad market, and how that might affect BRKB's return.

Thanks for your update on Price to Peak Book.

rrr12345