India, Aug. 23 -- The S&P 500 has reached a very rare valuation level. The S&P 500 Shiller CAPE ratio hit 40 in June 2026, marking only the second time in 155 years that the measure has reached this level.

The CAPE ratio is a long-term way to judge stock valuations. Yale economics professor Robert Shiller developed the cyclically adjusted price-to-earnings, or CAPE, ratio. Instead of looking at only the past four quarters of earnings, it uses a 10-year average of inflation-adjusted earnings.

Shiller's data goes all the way back to 1871. That gives investors more than 150 years of history to compare today's market valuation with previous periods. The CAPE ratio has usually stayed much lower. From 1871 through 2000, the S&P 500 Shiller CA...