The market has been very heavily concentrated in a small handful of stocks ('The Magnificent Seven') through much of 2023, with through early June, those seven stocks capturing essentially all S&P 500 gains while the remaining 493 stocks were flat to slightly negative.

No one cycle is always the same, so there is inherent imprecision in timing lags, meaning calls can be early and positionings can be early, but the typical 7-9 quarter lag provides a reasonable timing window.

Based on valuation levels and market conditions, there is a skew to longer-term downside risk than upside risk, indicating that the risk-reward profile is unfavorable for extended market exposure.

Grantham is not a permanent bear; he called many major bubble tops but was also very bullish in late 2008/early 2009 after the housing bust, demonstrating that his framework allows for identification of genuine buy opportunities after bubbles burst.