Generated August 15, 2026.
Overview
RSP and SPY are both broad U.S. equity ETFs tracking the S&P 500, but they weight their holdings fundamentally differently. SPY uses market-cap weighting (the standard approach), while RSP assigns equal weight to each of the 500 constituents. That structural difference drives divergent performance patterns, risk profiles, and income yields.
How they differ
The biggest distinction is weighting: SPY's market-cap methodology means the largest companies (currently dominated by mega-cap tech and financials) drive returns and volatility. RSP rebalances quarterly to maintain equal weight across all 500 stocks, which systematically overweights smaller constituents within the S&P 500 and underweights the heaviest ones. This makes RSP's beta of 0.84 materially lower than SPY's 1.0, reflecting its tilt away from the most volatile mega-cap names.
Income and fees differ modestly. RSP yields 1.45% versus SPY's 0.98%, partly because equal weighting captures more dividend yield from mid-cap and smaller-large-cap names that SPY's heavy concentration in non-dividend tech names depresses. RSP's expense ratio of 0.20% is twice SPY's 0.10%, a necessary cost of quarterly rebalancing. SPY's $812B in assets dwarfs RSP's $97.5B, making SPY the deeper, tighter-spread instrument for most investors.
Who each is best for
SPY: Investors seeking maximum liquidity and lowest cost exposure to the S&P 500's actual market composition, particularly those building a core large-cap holding in a buy-and-hold framework.
RSP: Investors seeking to tilt toward smaller constituents within the large-cap universe while moderating exposure to the heaviest mega-cap names, and who value the higher income yield that equal weighting provides.
Key risks to know
- Equal-weight rebalancing drag (RSP): RSP's quarterly rebalancing forces systematic selling of appreciated stocks and buying of laggards. This creates a structural return headwind relative to buy-and-hold market-cap weighting during sustained rallies in mega-cap stocks, which have dominated the past decade.
- Mega-cap concentration (SPY): SPY's market-cap structure means the fund's return is increasingly dominated by a handful of the largest technology and financial names. Concentration in those sectors can amplify downside in periods of broad-based selling or tech-specific weakness.
- Sector and size tilt risk (RSP): Equal weighting mechanically reduces RSP's weighting in Information Technology and increases exposure to Financials, Industrials, and other sectors. This creates style drift relative to the actual market, and performance divergence will persist if the equal-weight tilt falls out of favor.
- Liquidity and spread costs (RSP): RSP's $97.5B AUM is substantially smaller than SPY's. During volatile markets or large redemptions, RSP's tighter order flow may widen bid-ask spreads or create tracking error.
Bottom line
SPY is the canonical S&P 500 choice: lower cost, deeper liquidity, and pure market-cap exposure. RSP trades higher fees and rebalancing friction for a structural small-cap and equal-weight tilt that yields more income and exhibits lower volatility—but that tilt underperforms during mega-cap rallies and outperforms during mean-reversion periods. The choice depends on whether you want the market as it is (SPY) or a more balanced slice of the 500 (RSP). Past performance does not predict future results.
AI-generated analysis for educational purposes only. Verify important details independently; past performance does not guarantee future results.
