| Series | First | Latest | Min | Max |
|---|---|---|---|---|
| Equal-weight S&P 500 (RSP) | 100.0 | 1238.6 | 86.6 | 1238.6 |
| Cap-weight S&P 500 (SPY) | 100.0 | 1283.6 | 82.6 | 1286.4 |
RSP and SPY adjusted close indexed to 100 at the shared startRSP (S&P 500 equal-weight) and SPY (S&P 500 cap-weight), both daily, rebased to 100 at their shared start. Uses split- and dividend-adjusted close. RSP above SPY means the equal-weighted basket is winning: the average member is beating the largest constituents, a sign of broad participation rather than mega-cap concentration.
As of 11 Aug 2026, the Equal-weight S&P 500 (RSP) line stands at 1238.6 and the Cap-weight S&P 500 (SPY) line at 1283.6 (both base = 100 at the shared start). The Equal-weight S&P 500 (RSP) line is up 23.0% over the past year and above its long-run median of 353.0.
When RSP runs above SPY, the average S&P 500 member is beating the index's largest weights, which historically signals broad participation and a healthy internal market. When SPY leads, returns are concentrated in the mega-caps that dominate the cap-weighted index, the dominant pattern through the 2010s and 2020s tech-leadership era. The current spread is negative but narrow.
RSP and SPY hold identical constituents (the S&P 500) but weight them differently: SPY by market capitalisation, which concentrates in the largest names; RSP equally, which gives every member a fixed 0.2% weight. Comparing the two isolates the pure weighting effect with no sector or size noise, making this the cleanest possible measure of how concentrated index leadership is.
Equal-weighting tilts toward smaller-cap and more cyclical names within the S&P 500, so RSP outperformance overlaps with small-cap and value outperformance and is not a pure 'concentration' measure. RSP also has higher turnover and transaction costs from quarterly rebalancing. The window begins in May 2003, missing the late-1990s cap-weighted concentration peak. Treat the chart as context for market breadth, not investment advice.
On the rebased scale (100 at May 2003), RSP has risen to roughly 1,188 while SPY sits near 1,228, so cap-weight leads by roughly 3 percentage points over the full window despite the average stock having led for much of the post-crisis recovery. Cap-weight pulled ahead decisively after 2017 as mega-cap technology came to dominate the S&P 500, and the spread has remained narrow but negative through the AI-driven rally.
Strategists and market technicians use the equal-cap spread as the definitive gauge of internal market breadth. A widening cap-weight lead signals narrow mega-cap leadership and weak breadth, the condition that preceded the 2000-2002 and 2022 drawdowns; a widening equal-weight lead signals healthy broad participation.
Active large-cap managers typically outperform the cap-weighted S&P 500 during equal-weight leadership, because their diversified portfolios behave more like RSP than SPY. Performance consultants use the spread to explain active-versus-passive tracking and to identify regimes where active management has a structural tailwind.
Risk managers and allocators use the spread, alongside the Nasdaq-vs-broad-market benchmark, to gauge how exposed the S&P 500 is to a handful of mega-cap technology names. A sustained negative spread with widening Nasdaq leadership is the standard signature of concentration risk building in passive cap-weighted exposure.
As of 11 Aug 2026, the Equal-weight S&P 500 (RSP) line stands at 1238.6 and the Cap-weight S&P 500 (SPY) line at 1283.6 (both base = 100 at the shared start). The Equal-weight S&P 500 (RSP) line is up 23.0% over the past year and above its long-run median of 353.0.
This benchmark is built on daily data. The page is refreshed when the source publishes new observations; the freshness block below the chart shows the exact data-through date and when PIER20 last fetched the file.
The chart is built from Equal-weight S&P 500 (RSP) and Cap-weight S&P 500 (SPY), sourced from Yahoo Finance.
No, narrowly. Since May 2003 the RSP line has risen to roughly 1,188 while the SPY line sits near 1,228, so cap-weight leads equal-weight by roughly 3 percentage points. The average stock led for much of the post-crisis recovery, but cap-weight pulled ahead decisively after 2017 as mega-cap technology came to dominate the S&P 500.
The summary callout measures how much the RSP line has outperformed (positive) or underperformed (negative) the SPY line over the selected window, expressed as a percentage. A positive reading means the average S&P 500 stock is beating the index's largest weights; a negative reading means mega-cap concentration is doing the work.
Both ETFs hold the 500 S&P constituents, but SPY weights them by market cap, so Apple, Microsoft, Nvidia and the other mega-caps dominate. RSP gives every constituent a fixed equal weight, so a 1% move in a small S&P member moves the index as much as a 1% move in Apple. When mega-caps outperform the average, SPY beats RSP even though they hold the same names.
Large vs small compares two different index universes (S&P 500 vs Russell 2000), isolating the size factor across different constituent sets. Equal vs cap compares two different weightings of the same S&P 500 constituents, isolating intra-index concentration. The two can diverge: equal-weight can beat cap-weight even when large caps beat small caps, if the average large cap is beating its own mega-caps.
One tested idea, through the evidence stack. No migration of any kind.