Equal-Weight S&P 500 Index Funds Explained
The standard S&P 500 is dominated by a handful of giants. An equal-weight version like RSP holds the same 500 names but gives each the same slice — a very different bet on the same index.
Don't have time? Here's what you need to know:
- 1An equal-weight S&P 500 fund like RSP holds the same 500 stocks but gives each the same ~0.2% weight, slashing megacap concentration.
- 2Equal weighting creates a mid-cap and value tilt and a disciplined sell-high/buy-low rebalance, versus the growth tilt of cap-weighted VOO/SPY.
- 3Leadership rotates: equal weight wins on broad rallies, cap weight wins when a few megacaps dominate; neither is permanently superior.
- 4The trade-offs are a higher fee (~0.20% vs ~0.03%), more turnover, and the patience to endure stretches of trailing the headline index.
Same 500 Stocks, Very Different Weights
The familiar S&P 500 is capitalization-weighted: a company's slice of the index is proportional to its market value, so the largest firms dominate. In recent years a handful of megacap technology companies have grown so large that the top names alone make up a sizable chunk of funds like VOO and SPY.
An equal-weight S&P 500 fund holds the exact same 500 companies but gives each one the same weight — roughly 0.2% apiece — and rebalances back to equal periodically. The best-known example is RSP, the Invesco S&P 500 Equal Weight ETF. The holdings list is identical; only the weighting scheme changes, and that change has large consequences.
Cutting Megacap Concentration, Adding a Size Tilt
Equal weighting dramatically reduces concentration risk. In a cap-weighted fund, your fortunes ride heavily on the biggest few stocks; in an equal-weight fund, no single name can dominate, because the smallest member counts as much as the largest. If you're uneasy about how much of a standard S&P 500 fund sits in a few giant companies, equal weight is the direct answer.
The flip side is that equal weighting effectively tilts toward the smaller and more value-oriented companies within the index. By holding as much of the 500th-largest firm as the largest, the fund leans into mid-cap and value exposure relative to the cap-weighted version. That tilt is the source of both its potential edge and its periods of lagging behind.
| Cap-weighted (VOO/SPY) | Equal-weight (RSP) | |
|---|---|---|
| Holdings | S&P 500 | Same S&P 500 |
| Weighting | By market value | Equal (~0.2% each) |
| Top-10 concentration | High | Low |
| Effective tilt | Megacap / growth | Mid-cap / value |
| Expense ratio | ~0.03% | ~0.20% |
| Rebalancing | Self-adjusting | Periodic, to equal |
When Equal Weight Wins and When It Lags
Neither approach is permanently superior — they take turns. Equal weight tends to outperform when market gains are broad and smaller companies participate, or when the dominant megacaps stumble. Cap weight tends to win when a handful of giant winners drive most of the market's return, as has happened during stretches dominated by big tech.
Because equal weight rebalances back to equal, it systematically trims winners and adds to laggards — a disciplined "sell high, buy low" mechanic within the index. Over very long periods that has sometimes given it a modest edge, but it comes with stretches of meaningful underperformance when megacaps lead. You're making a deliberate bet on breadth over concentration.
Important: Equal weight isn't a free lunch. It can underperform cap weight for years at a time, especially during megacap-led rallies, and the periodic rebalancing makes it a touch less tax-efficient and a bit pricier.
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Who Should Consider Equal Weight
An equal-weight S&P 500 fund makes sense for an investor who wants S&P 500 companies but is specifically worried about concentration in a few megacaps, or who wants a built-in value and size tilt without leaving large-cap U.S. stocks. It can also serve as a satellite alongside a cap-weighted core to dilute top-heaviness.
The costs to weigh are a higher expense ratio (around 0.20% versus 0.03% for plain S&P 500 funds), higher turnover from rebalancing, and the willingness to sit through periods of lagging the headline index. If those don't bother you and you believe broad participation will reward you, equal weight is a coherent choice. If you'd rather keep it simple and cheap, the cap-weighted fund remains the default.
Frequently Asked Questions
What's the difference between RSP and VOO?
Both hold the same 500 S&P 500 companies, but VOO weights them by market value (so megacaps dominate) while RSP gives each company the same ~0.2% weight and rebalances back to equal. RSP has far less concentration and a mid-cap/value tilt, but costs more (~0.20% vs ~0.03%) and can lag VOO during megacap-led rallies.
Is equal-weight S&P 500 better than cap-weighted?
Neither is permanently better; they trade leadership. Equal weight tends to win when market gains are broad or megacaps stumble, while cap weight wins when a few giant stocks drive returns. Equal weight reduces concentration risk and adds a value/size tilt, at the cost of a higher fee and stretches of underperformance.
Why does equal weight cost more than a normal S&P 500 fund?
Equal-weight funds must periodically rebalance back to equal weights, trimming stocks that have risen and buying those that have fallen. That ongoing trading is more involved than a self-adjusting cap-weighted fund, so the expense ratio is higher — around 0.20% versus roughly 0.03% for a standard S&P 500 fund.
Does equal weight reduce risk?
It reduces concentration risk — your return no longer hinges on a handful of megacaps. But it doesn't reduce overall market risk; it's still 100% large-cap U.S. stocks. By tilting toward smaller and value names, it can actually be more volatile than the cap-weighted index in some environments, just with different drivers.
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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.