S&P 500 closed at an all-time high but 8 of 11 sectors finished lower. This is maximum concentration — the index being carried by a handful of AI mega-cap names while the broader market quietly bleeds. When breadth diverges this sharply from the index level, I watch SKEW and the VIX term structure closely. A narrow market can hold up for longer than expected, but it leaves zero margin for error if leadership rotates or implied vol starts repricing.