The choice between the Invesco S&P 500 Equal Weight ETF (NYSEARCA:RSP) and the SPDR S&P 500 ETF Trust (NYSEARCA:SPY) looks trivial on a fund screener. You have the same 500 companies, both tracking the S&P 500, and both are cheap. The weighting scheme is the entire story, as SPY’s cap-weighted holdings allocate 7.58% of the portfolio to NVIDIA and 6.66% to Apple. On the other hand, RSP hands each stock roughly 0.20% at every quarterly rebalance, and that single rule change is the bet, and which side wins flips with the regime.
What each fund is actually betting on
SPY is a momentum vehicle by construction: cap-weighting hands the biggest winners an ever-larger share of every new dollar, so the fund is implicitly long whatever has already worked. Today that means a heavy tilt toward AI infrastructure and mega-cap platforms. The Magnificent Seven alone add up to roughly 32% of the fund as of March 31, 2026, with the top 10 holdings accounting for about 38.6%. In RSP, those same seven names command only about 1.4% combined. That gap of 32% versus 1.4% is the entire argument in two numbers. SPY wins when the biggest companies keep getting bigger.
RSP makes the opposite bet with equal weighting, forcing a quarterly trim of whatever just ran, and a top-up of whatever lagged. That mechanical mean reversion gives RSP a structural mid-cap tilt within the S&P 500 and roughly doubles its weight to sectors like industrials, financials, and materials relative to SPY. It needs market breadth, value rotation, or mega-cap stumbles to outperform. It trades concentration risk for sector and mid-cap risk, a different risk profile rather than a safer one.
Where the difference shows up
The AI-led mega-cap rally has owned the scoreboard for years. From January 3, 2022, through June 9, 2026, SPY returned 54.29% versus 38.08% for RSP. Stretch it to five years, and SPY’s 73.99% beats RSP’s 49.59%. Over ten years, SPY’s 250.86% tops RSP’s 207.45%. Pick a window that includes the Magnificent 7’s run and SPY wins.
The picture inverts when leadership narrows or breaks. 2026 has started showing exactly that. RSP is up 9.67% year to date while SPY is up 8.38%, and the gap has widened recently. Over the past month, RSP gained 2.49% while SPY was essentially flat at -0.08%. In the last week, SPY fell 2.96% against a 0.4% dip for RSP. When the mega-caps cough, equal weight reasserts itself quickly.
The practical comparison
| Metric | RSP | SPY |
|---|---|---|
| Weighting | Equal (~0.2% per name) | Cap weighted |
| Expense ratio | 0.20% | 0.0945% |
| AUM | ~$89B | ~$779B |
| Top holding weight | ~0.2% | 7.58% (NVIDIA) |
| Rebalance | Quarterly | None (drifts with market cap) |
The roughly 10-basis-point fee gap is real but small, and the higher structural cost in RSP is turnover from quarterly rebalancing, which can hurt tax efficiency in a taxable account relative to SPY’s drift-with-the-market design.
The verdict
For an investor who believes the largest US companies will continue to lead, SPY is the cleaner and cheaper way to express that view. For someone who already owns plenty of mega‑cap tech through QQQ, individual Mag 7 positions, or a growth tilt elsewhere, RSP delivers better diversification inside the same index, with noticeably lower single‑stock risk and a built‑in value lean. The whole choice comes down to one question. Do you expect mega‑cap dominance to continue, or does market breadth finally return? If the early 2026 rotation keeps building, RSP’s equal‑weight discipline starts earning its 0.20% fee quickly, especially for anyone thinking about concentration risk or index diversification.
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