Formula & Calculation Mechanism
Count of S&P 500 constituents with Close > 200D MA divided by 500
Healthy bull market advances are supported by broad participation (>60% of stocks above 200D MA). Narrow rallies (<40%) indicate fragile market structure.
Market Impact on US Equities & S&P 500
Breadth expanding above 65% confirms strong cyclical bull trends. Divergence (Index at highs but Breadth falling) warns of impending top.
Historical Precedents & Bull/Bear Regimes
In late 2021, S&P 500 hit new highs while >200D MA breadth fell below 50%, accurately telegraphing the 2022 bear market.