The S&P 500 closed October 5 less than 1% from its all-time high while only 42% of its members traded above their 200-day moving average, a breadth reading last recorded in March 2000 according to Dow Jones Market Data. The index has spent most of 2026 at or near records, but the advance is being carried by a shrinking cohort of stocks, a condition that historically precedes trouble for bull-market sustainability.
Concentration has become the story
Technology names now represent roughly 38% of the capitalization-weighted index, and the ten largest holdings account for approximately the same share. For years that top-heaviness was irrelevant because the mega-caps were also the best performers. The data now show tech and energy as the only two sectors beating the index year to date; the other nine lag, with financials, utilities, communication services and consumer discretionary all in negative territory.
The equal-weight alternative
The Invesco S&P 500 Equal Weight ETF (RSP) holds every constituent at a 0.2% weight at each quarterly rebalance. Technology drops to about 16% of the portfolio, and five sectors each command at least 9%. The quarterly rebalance imposes a mechanical buy-low, sell-high discipline that trims winners and adds to laggards, reducing concentration risk without exiting the market.
What to watch next
A broadening of participation, more sectors crossing above their 200-day averages, would validate the current highs. Until then, the index’s vulnerability to a tech momentum pause remains the central risk for anyone owning the cap-weighted benchmark.