S&P 500 vs Equal-Weight S&P 500

SPY weights by free-float market cap. April 2026 top weights: Apple ~7%, Microsoft ~7%, Nvidia ~7%, Amazon ~4%, Google (combined) ~4%, Meta ~2.5%, Tesla ~2%, Broadcom ~2%, Berkshire Hathaway ~2%, JPMorgan ~1.5%. The top 10 represent approximately 35 percent of SPY assets. Mega-cap concentration peaked near 38 percent in early 2024.

RSP holds the same 500 stocks but weights each at approximately 0.20 percent (1/500). Quarterly rebalancing forces selling of recent winners back to 0.20 percent weight and buying of recent losers. The mechanical buy-low-sell-high discipline produces structural alpha when sector breadth is healthy.

The practical implication: SPY is essentially a Magnificent 7 wrapper plus 493 other stocks. RSP is a true diversified equity exposure where each name contributes equally. When mega-caps lead, SPY outperforms; when breadth is healthy, RSP outperforms.

From 2014 through 2024, SPY outperformed RSP cumulatively by approximately 70-80 percentage points, the longest sustained equal-weight underperformance in RSP's history. The driver was mega-cap dominance: AAPL, MSFT, NVDA, GOOGL, AMZN, META, TSLA combined market cap reached $20 trillion by early 2024, dominating SPY weighting and returns.

The 2025-2026 rotation has been material. RSP outpaced SPY by ~5 percentage points YTD 2026. The catalysts: AI capex translation questions weighing on mega-cap tech; Iran war-related sector rotation favoring industrials/financials/healthcare; Fed cut anticipation favoring rate-sensitive sectors that are equal-weighted in RSP but under-weighted in SPY.

The equal-weight outperformance is not just SPY-specific weakness; it reflects genuine breadth improvement. The number of S&P 500 stocks above their 200-day moving average has risen from approximately 50 percent in early 2024 to approximately 75 percent in April 2026.

RSP and SPY have similar overall sector weights but with material differences in concentration. SPY: Tech ~30 percent, Financials 13 percent, Healthcare 12 percent, Consumer Discretionary 11 percent, Communications 9 percent, Industrials 8 percent, Consumer Staples 6 percent, Energy 4 percent. The Tech weight is dominated by 3-4 mega-caps.

RSP April 2026 sector weights: Industrials ~16 percent, Financials ~15 percent, Information Technology ~14 percent, Healthcare ~13 percent, Consumer Discretionary ~10 percent, Consumer Staples ~6 percent, Energy ~4 percent, Communications ~5 percent, Utilities ~5 percent, Real Estate ~5 percent, Materials ~4 percent. RSP's 14 percent Tech weight versus SPY's 30 percent is the central structural difference.

The practical implication: RSP is more cyclical, more value-tilted, and less duration-sensitive than SPY. Strong cyclical industries (industrials, financials) get over-weighted in RSP; mega-cap tech gets under-weighted. The pair captures the structural tilt: cap-weight tracks mega-cap tech leadership; equal-weight tracks broad-economy leadership.

Five regimes describe SPY-vs-RSP through cycles. Regime 1 (early-cycle 2003-2007): RSP outperformed SPY by ~30 percentage points cumulatively as broad-economy recovery favored equal-weight exposure. Regime 2 (mid-cycle 2010-2014): RSP roughly matched SPY. Regime 3 (mega-cap dominance 2014-2024): SPY outperformed RSP by 70-80pp cumulatively (longest sustained equal-weight underperformance in RSP's history). Regime 4 (current 2025-2026 rotation): RSP outperforming SPY by ~5pp YTD 2026.

The long-run pattern: equal-weight outperforms cap-weight during early-cycle expansions, mid-cycle stable growth, and recovery phases. Cap-weight outperforms during mega-cap dominance eras and recessions (mega-caps show defensive characteristics). The 2014-2024 era was an unprecedented 10-year mega-cap dominance; the 2025-2026 rotation may be reverting to historical norms.

The academic literature supports the equal-weight long-run advantage. Multiple studies show equal-weight S&P 500 has produced 1-2 percentage points annual outperformance over cap-weight since 1958 inception. The 2014-2024 era was the historical exception, not the norm.

SPY concentration in the top 10 stocks reached 38 percent in early 2024, the highest in S&P 500 history. The previous record was 33 percent during the 1999 Tech Bubble peak. The current 35 percent concentration remains elevated.

The concentration produces specific risks. First, idiosyncratic stock risk: a 30 percent NVDA decline produces approximately 2 percent SPY drag from NVDA alone. Second, sector concentration risk: tech-specific shocks (AI capex disappointments, antitrust actions) hit SPY disproportionately. Third, valuation compression risk: if AI multiples compress, top 10 holdings affect SPY materially.

RSP avoids all three concentration risks. NVDA at 0.20 percent of RSP cannot produce material drag. Tech-specific shocks affect only ~14 percent of RSP. Valuation compression affects RSP but proportionally based on equal weights, not amplified by concentration.

The practical implication: RSP provides downside protection against mega-cap concentration scenarios. If Magnificent 7 sees significant correction, SPY would fall harder than RSP. The April 2026 rotation reflects partial concentration unwind that has favored RSP.

RSP rebalances quarterly, forcing the index to sell appreciated holdings (winners reverting from above 0.20 percent weight back to 0.20 percent) and buy depreciated holdings (losers reverting from below 0.20 percent back to 0.20 percent). This produces structural buy-low-sell-high discipline that cap-weight indexes cannot replicate.

The rebalancing benefit compounds. Over multi-year horizons, the discipline captures mean reversion in individual stocks. A stock that doubles between rebalances is sold back; a stock that halves is bought back. Both moves benefit subsequent performance compared to leaving positions unchanged.

The discipline cost: turnover. RSP turnover is approximately 27 percent annually (vs SPY ~3 percent). Higher turnover produces higher transaction costs and tax inefficiency in taxable accounts. The expense ratio differential (RSP 0.20 percent vs SPY 0.0945 percent) plus turnover-related costs slightly offset the rebalancing benefit. Net structural advantage for equal-weight is approximately 0.5-1.0 percentage points annually after costs.

RSP realized volatility is approximately 17 percent annualized vs SPY 16-17 percent. The two are nearly equivalent in volatility despite very different concentration profiles. The reason: RSP's broader diversification offsets its higher cyclicality.

60-day rolling correlation between SPY and RSP averages approximately 0.92. During risk-off periods correlation rises to 0.95+; during sector rotation episodes drops to 0.85-0.90. The correlation is the highest among major equity-pair correlations because both indexes hold the same 500 stocks, just weighted differently.

For pair-trade sizing, the near-equivalent volatility produces a hedge ratio of approximately 1:1 (dollar-weighted) for beta-neutral positioning. The pair is the lowest-volatility equity-vs-equity pair trade available because of the high correlation; small spread moves produce reliable signals.

Recession history is mixed. The 2008-2009 recession: SPY fell 56 percent peak-to-trough vs RSP 60 percent (4pp SPY outperformance, mega-cap defensiveness). The 2020 COVID recession: SPY -34 percent vs RSP -38 percent (4pp SPY outperformance). The 2022 hiking-cycle bear market: SPY -25 percent vs RSP -22 percent (3pp RSP outperformance, growth-stock multiple compression hurt SPY more).

The pattern: in pure-equity recessions (2008, 2020), SPY outperforms because mega-caps show defensive characteristics. In hiking-cycle bear markets (2022), RSP outperforms because growth-stock multiple compression dominates. The 2026 recession scenario type matters.

For demand-driven recessions, expect SPY to outperform RSP by 3-5 percentage points peak-to-trough. For hiking-driven scenarios, expect RSP to outperform SPY by similar magnitudes. The current April 2026 setup is neither: mega-cap rotation plus Iran war defensive flow plus Fed cut anticipation produced unusual RSP outperformance.

For pair traders, the SPY/RSP ratio currently trades at approximately 3.5 (SPY $708 / RSP ~$202 estimate). The 12-month range is approximately 3.4 to 3.7. The 5-year range is approximately 3.2 to 3.7 (SPY peak in early 2024). Above 3.7 indicates SPY extreme outperformance (mega-cap dominance period); below 3.4 indicates RSP outperformance (broadening rally).

Long SPY / short RSP captures continued mega-cap dominance: benefits from AI capex translation success, mega-cap earnings beats, passive flow concentration in cap-weight ETFs, and recession-driven flight to mega-cap quality. Long RSP / short SPY captures broadening rally and concentration unwind: benefits from continued mega-cap rotation, AI translation questions, sector-rotation episodes. Position sizing should account for nearly equivalent volatility (RSP 17% vs SPY 16-17%).

The pair has produced highly variable returns. From 2014-2024 cumulative long SPY short RSP gained 70-80 percentage points. YTD 2026 long RSP short SPY has gained 5 percentage points. The spread is one of the cleanest market-breadth measures available daily.

SPY ~$708, RSP ~$202 estimate, ratio 3.5. SPY YTD -4% through late March then recovered to +1-4% currently; RSP YTD +1% through late March, holding outperformance. Number of S&P 500 stocks above 200-day MA approximately 75 percent in April 2026, up from ~50 percent early 2024.

Forward-looking: April 30 mega-cap tech earnings will determine SPY-vs-RSP direction for next 60 days. Strong AI translation evidence would compress RSP outperformance and reactivate SPY dominance. AI translation disappointment would extend RSP outperformance. Iran ceasefire confirmation supports continued sector rotation favoring RSP's broader exposure. Iran escalation reverses, favoring SPY mega-cap defensive flow.

Watch the SPY/RSP ratio for moves outside 3.4 to 3.7. Below 3.4 indicates RSP extreme outperformance (potential trend continuation if breadth keeps improving). Above 3.7 indicates SPY mega-cap dominance regaining (trend reversal). The pair is the cleanest equity-market-breadth indicator available and should be a core component of any market-rotation analysis.