Bear-side framing first. Breadth has narrowed materially: five mega-caps account for 71% of YTD index return. A cap-weighted index riding on five names is a fragile index; broadening would require either a leadership rotation or a mean-reversion. The historical percentile column is the contextual sanity check — an absolute reading without history is decoration.
Signal: narrowing
Per-row diagnostics
Indicator
Value
Δ
10y %ile
% S&P 500 above 200d MA
47.0%
▼
P28
% S&P 500 above 50d MA
41.0%
▼
P22
% making new 52-week highs
4.6%
▼
P31
NYSE adv/dec line slope (20d)
-0.34
▼
P18
Cap-weight − equal-weight YTD return spread
9.2%
▲
P92
Top 5 mega-caps share of YTD index return
71.0%
▲
P96
A breadth signal is a leading-but-noisy indicator: narrowing leads drawdowns more often than not, but the lead time has historically ranged from six weeks to nine months. Pair this surface with the regime scorecard and the scenarios page; one signal in isolation is not a portfolio decision.
