RSP vs VOO: Equal Weight, or the Usual Cap-Weighted S&P 500?

Overview

RSP and VOO both track the S&P 500, but they weight their holdings fundamentally differently. VOO uses market-cap weighting, giving the largest companies the biggest influence on the fund's moves. RSP uses equal weighting, giving each of the 500 stocks the same dollar allocation, which tilts the fund toward smaller constituents within the S&P 500 and produces a notably different risk and return profile.

How they differ

The equal-weight approach makes RSP behave more like a mid-cap tilt than a pure S&P 500 tracker. Equal weighting inherently overweights smaller stocks in the index and underweights mega-cap names, pushing RSP's beta to 0.83, compared to VOO's 1.0. This structural difference flows through to yield: RSP distributes 1.53%, while VOO yields 1.04%, reflecting RSP's tilt toward higher-dividend smaller-cap value stocks. Cost is another split—VOO charges 0.03%, among the cheapest in the industry, while RSP's 0.20% is still low but covers the operational overhead of rebalancing to equal weight quarterly. VOO is vastly larger, with $1041B in assets versus RSP's $96.6B, a difference that reflects VOO's role as the market's dominant S&P 500 core holding.

Who each is best for

RSP: Fits investors drawn to a value and small-cap tilt within the S&P 500 universe, who tolerate higher volatility and want modestly higher income than market-cap weighting provides, and who are willing to pay slightly more in fees for the rebalancing discipline.

VOO: Fits investors seeking the purest market-cap-weighted S&P 500 exposure with minimal cost, who prefer to match broad equity benchmarks without tilting toward any subset of the index, and who prioritize simplicity and the largest asset base.

Key risks to know

• Equal-weight rebalancing drag. RSP must systematically sell winners and buy losers to maintain equal weighting. In sustained bull markets where large-cap stocks outpace smaller ones, this rebalancing can underperform market-cap weighting—a structural headwind, not a temporary anomaly.

• Size and style tilt concentration. RSP's equal-weight structure concentrates exposure toward smaller, often more volatile S&P 500 constituents. If mid-cap and smaller large-cap stocks underperform mega-cap leaders, RSP's returns can lag VOO materially, as holding overlaps diverge significantly by market-cap buckets. Over decades, that compounding difference grows substantial, especially for taxable accounts where the tax efficiency of market-cap weighting can compound the advantage further.

• Volatility and drawdown depth. RSP's beta of 0.83 reflects lower historical volatility than the market, but that masks the true downside risk of its small-cap tilt. In sharp equity corrections, smaller stocks often fall harder than mega-cap leaders, so RSP's realized drawdowns may exceed its beta suggests.

Bottom line

VOO is the simpler, cheaper choice if you want the S&P 500 as it actually trades. RSP bets that equal-weighting a static list of 500 companies will outpace market-cap discipline and offers higher income in exchange for style tilt and rebalancing costs. The choice hinges on whether you believe mean reversion among S&P 500 constituents justifies the fee drag and concentration risk—or whether you'd rather minimize cost and hold the market as it weights itself. Past performance does not guarantee future results.