The Shiller P/E ratio, a measure of long-term market valuation, has only crossed 40 three times: 1929, 1999, and today. The first two instances preceded major market crashes (The Great Depression, Dot-com Bust) and were followed by a decade or more of flat or negative real returns for investors.

A key warning sign of a market top is low correlation, where different indices (e.g., NASDAQ, S&P 500, Russell 2000) peak at separate times. This indicates that capital is rotating from exhausted leaders to laggards in a final, desperate search for returns. When this rotation ends, the next likely move is a broad, correlated decline.

Historical data shows no exceptions to the rule that an asset class reaching a two-standard-deviation (two sigma) valuation above its long-term trend will eventually return to that trend. This statistical certainty applies to stocks, bonds, commodities, and currencies, making severe drawdowns from such peaks inevitable.

Contrary to its name, the 'speculation' phase is not a bullish signal. In Michael Howell's framework, it's the final stage before 'turbulence,' analogous to autumn before winter. This phase indicates investors should be reducing risk as a market downturn approaches, not increasing it.

The creation of tertiary funds—funds that buy LP interests in secondary funds—indicates that private markets are so starved for liquidity that capital is being layered multiple levels away from the actual value-creating companies. This complex financial engineering mirrors the CDOs of the 2008 crisis and suggests a potential market top.

A key indicator of a bubble's final stage, observed only four times in U.S. history (1929, 1972, 2000, 2021), is when speculative, high-beta stocks that led the rally start to fall sharply while blue-chip indices continue to grind higher. This market divergence is a 'primal scream' that a crash is imminent.

History shows that markets with a CAPE ratio above 30 combined with high-yield credit spreads below 3% precede periods of poor returns. This rare and dangerous combination was previously seen in 2000, 2007, and 2019, suggesting extreme caution is warranted for U.S. equities.

A market where the average stock's volatility is much higher than the overall index's volatility indicates speculative, late-cycle behavior. This divergence, often driven by retail options trading, suggests market froth and parallels previous peaks like 1999.

The CAPE ratio, which compares stock prices to average 10-year earnings, is at a level seen only twice before in history: just before the 1929 Great Depression and the 1999 dot-com bubble. This indicates a severely overvalued market ripe for a major correction.