The price/book value ratio of the S&P 500 has seen a significant increase since around 2009, reaching its peak in the recent years, while Berkshire Hathaway's price/book value ratio has remained relatively stable and much lower in comparison.
The divergence in price/book value ratios suggests that the market is valuing S&P 500 companies more aggressively in terms of their book value, possibly reflecting a shift towards industries with higher valuation metrics, such as technology.