"Depending on whether you look at data from 1999 or 2003 or 2008, models applied to today's ratio suggests one might anticipate a one year forward return of inflation + 14.0% to inflation + 14.9% from here."

Another variable that affects Berkshire's forward 1-year returns, besides starting P/B, is the return of the broad stock market, or more specifically the return of Berkshire's equity portfolio. Berkshire's equity portfolio, net of deferred taxes, still makes up about half of Berkshire's IV. In 2022 the S&P 500 declined 18%, while Berkshire's equity portfolio declined about 17% and BRKA stock rose just over 3%. Plotting the annual returns of BRKA stock versus the return of the S&P 500 from 1994 to 2022, the trendline return of BRKA when the S&P 500 returns -18% is -4%. Therefore one question regarding Berkshire's return over the next 12 months is, "What will the S&P 500 return over the next 12 months?"

The starting point for forecasting the return of BRK stock is value growth and P/value, which are currently about 10%/yr and 1.0, suggesting a forward return of 10%, but with the S&P 500 trading at a trailing P/E of 24, suggesting a return for the S&P of about 4% (considerably less if there is a correction in the next 12 months) I would lower the forecast for BRKA, possibly quite a bit.