Market-Cap vs Equal-Weight ETFs
Cap-weighting lets the biggest companies dominate; equal-weighting gives all 500 the same stake. RSP vs VOO is the textbook example, and the gap shows up in concentration and cost.
Don't have time? Here's what you need to know:
- 1Cap-weighted funds (VOO) size holdings by company value, letting a few mega-caps dominate; equal-weight funds (RSP) give every holding the same slice.
- 2Equal-weighting cuts concentration and adds a mid-cap/value tilt, but costs more (~0.20% vs ~0.03%) and turns over more.
- 3Cap-weighting is cheaper, more tax-efficient, and self-adjusting; equal-weight's rebalancing can create taxable distributions.
- 4A common approach is a cap-weighted core plus a smaller equal-weight satellite to dilute mega-cap concentration.
Two Ways to Weight the Same 500 Stocks
A market-capitalization-weighted index, the standard for most index funds, sizes each holding by the company's total market value. The largest companies get the largest weights, so a handful of mega-caps can dominate the fund. In a cap-weighted S&P 500 fund like VOO, the top 10 holdings have at times made up roughly a third of the entire fund.
An equal-weight index gives every company the same slice regardless of size. The classic example is RSP, the Invesco S&P 500 Equal Weight ETF: it holds the same 500 companies as VOO, but each gets about 0.2% of the fund instead of being scaled by market value. Same stocks, radically different weights, and that difference drives everything else about how the two behave.
Concentration, Sector Tilt, and Behavior
Cap-weighting concentrates the fund in whatever has grown largest, which in recent years has meant heavy exposure to a small group of mega-cap technology names. That works beautifully when those giants lead, and it stings when they stumble; the fund's fate is tied to its biggest positions. Cap-weighting also automatically tilts toward whatever sector is most valued, currently technology.
Equal-weighting deliberately breaks that concentration. By holding every company at the same weight, RSP gives far more relative emphasis to mid-sized and smaller companies in the index and tilts away from the dominant mega-caps. The result is a built-in diversification across the membership and a structural value-and-size tilt. Equal-weight has historically outperformed in environments where smaller companies and value stocks lead, and lagged when a few mega-caps drive the market.
| Feature | Cap-Weight (VOO) | Equal-Weight (RSP) |
|---|---|---|
| Weighting method | By company size | Every holding ~equal |
| Top-10 concentration | High (often ~30%+) | Low (~2%) |
| Effective tilt | Mega-cap / growth | Mid-cap / value |
| Expense ratio | ~0.03% | ~0.20% |
| Rebalancing | Minimal (self-adjusting) | Quarterly, higher turnover |
| Tends to lead when | Mega-caps dominate | Broad market / smaller names lead |
The Cost and Turnover Difference
Equal-weighting is not free. RSP charges around 0.20%, compared with roughly 0.03% for VOO, because it requires more maintenance. A cap-weighted fund is largely self-adjusting: as a company grows, its weight grows automatically, so the fund rarely needs to trade. An equal-weight fund must periodically rebalance, selling the winners that have grown beyond their target weight and buying the laggards, to push every holding back to equal.
That regular rebalancing generates higher turnover, which adds trading costs and, in a taxable account, can produce more capital-gains distributions. So equal-weight buys you diversification and a value-size tilt at the price of a higher expense ratio and lower tax efficiency. Whether that trade is worth it depends on your view of concentration risk and on which environment you expect to reward.
Important: Equal-weight's higher turnover can generate more taxable capital-gains distributions. It often fits better in a tax-advantaged account than a taxable one.
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Which Approach Fits You
Cap-weighting is the lower-cost, more tax-efficient, and more hands-off default, and over very long horizons it has been hard to beat. Its main drawback is the concentration that builds up at market tops, when a few names carry an outsized share of the fund. If you are comfortable owning the market as the market actually is, cap-weighting is the simplest choice.
Equal-weighting appeals to investors who specifically want to reduce mega-cap concentration, lean toward mid-caps and value, and avoid having a handful of stocks dominate their outcome. It is best used deliberately, often as a satellite alongside a cap-weighted core, with eyes open to the higher fee and turnover. Neither is universally superior; they simply express different beliefs about concentration and where future returns will come from.
Tip: A common compromise is to hold a cheap cap-weighted fund as your core and add a smaller equal-weight position if you specifically want to dilute mega-cap concentration.
Frequently Asked Questions
What is the difference between RSP and VOO?
Both hold the same 500 S&P companies, but VOO weights them by market size, so mega-caps dominate, while RSP weights every company roughly equally at about 0.2% each. RSP is more diversified across its membership with a mid-cap and value tilt, but it charges more (~0.20% vs ~0.03%) and has higher turnover.
Is equal-weight better than market-cap weighting?
Neither is universally better. Equal-weight reduces concentration and tilts toward mid-caps and value, which has helped in broad-market environments but hurt when a few mega-caps lead. It also costs more and is less tax-efficient. Cap-weighting is cheaper, more tax-efficient, and hands-off, but concentrates risk in the largest holdings. The right choice depends on your view of concentration.
Why does the equal-weight ETF charge a higher fee?
Equal-weight funds like RSP must rebalance regularly, selling holdings that have grown above their target weight and buying laggards, to keep every position roughly equal. That maintenance generates higher turnover and trading costs, which is reflected in an expense ratio around 0.20% versus about 0.03% for a self-adjusting cap-weighted fund.
Should I use equal-weight in a taxable account?
Be cautious. Equal-weight funds rebalance frequently, which raises turnover and can generate more capital-gains distributions that are taxable in a taxable brokerage account. Many investors prefer to hold equal-weight funds in a tax-advantaged account like an IRA, where those distributions are not taxed inside the wrapper.
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Alex Harrington
CFA Level II Candidate, Finance & Economics
Alex Harrington is an independent ETF researcher and personal finance writer with over 8 years of experience analyzing exchange-traded funds. A CFA Level II candidate with a background in economics, Alex has reviewed 800+ ETFs and helped thousands of beginners build their first investment portfolios through clear, jargon-free education.
This content is for educational purposes only and does not constitute financial advice. Past performance does not guarantee future results. Consult a licensed financial advisor before making investment decisions.