Breadth, Leadership & the Tape

How to check whether a rally is broad or narrow, why the behavior of leading stocks matters, and what real breadth readings looked like at 2025 and 2026 turning points.

Breadth: how many stocks are joining in

An index can rise while most stocks go nowhere, if a handful of giant companies do the lifting. Breadth measures participation. A common breadth gauge is the share of stocks trading above their 50-day moving average. High readings mean a broad rally; low readings mean few stocks are healthy.

Other breadth measures include the number of stocks making new highs versus new lows, and the advance-decline line, a running total of rising stocks minus falling stocks each day.

Real readings: the share of stocks in our data above their 50-day average.

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