According to @charliebilello, the S&P 500's trailing 12-month operating P/E reached 26 in 2025, which is 31% above the historical average since 1989 of 19.8 (source: @charliebilello). @charliebilello also noted this is the third consecutive year of multiple expansion for the index (source: @charliebilello). He specified the methodology uses trailing 12-month operating EPS with estimated Q4 EPS included (source: @charliebilello).