Breadth & Participation
How much of the S&P 500 is actually moving when the index moves, counted on each day's real membership.
Mixed. 51.8% of S&P 500 members trade above their own 200-day average. The reading sits mid-range against its own decade. Participation reads mixed: below 40.0% is narrow, above 60.0% is broad. As of 2026-10-19.
What this measures
Breadth & Participation asks how much of the S&P 500 is actually moving when the index moves, since an index average can be carried by a handful of its largest weights. The headline series is the share of members trading above their own 200-day average, counted on the membership that stood on each historical day rather than today's list applied backwards.
How to read it
High readings mean ordinary stocks are carrying the market; low readings mean fewer names are holding it up. Equal weight against cap weight, the advance-decline line and new highs minus lows show the same thing from other angles. When the index makes a high while those internals slope the wrong way, fewer names are doing the lifting, which is the classic divergence worth taking seriously.
Membership and the coverage gap
Companies mostly leave the index by being bought out at a premium, usually while above their averages, so back-applying today's list removes the strongest histories. Membership is rebuilt from Wikipedia's record of every index change back to 1976. Yahoo has deleted the price history of most acquired members, which thins early-window coverage and biases those readings slightly downward; the covered count travels with the payload and is every percentage's denominator. Sector tags are each company's current classification applied to today's reading.
Breadth thrusts, and why the base rates look unimpressive
What this page is not
It is not a timing signal on its own. Breadth works as a confirmation layer, so read it next to positioning and the rate path, not instead of them.