S&P 500 ETFs and index funds compared: which is the best S&P 500 ETF?

1. What you are buying

The S&P 500 holds 503 of the largest US companies, weighted by size. The ten largest are 37.9% of the index (Vanguard factsheet, 30 Jun 2026). It is a single-country bet: if you already own an MSCI World fund, about 72% of it is US too, so adding an S&P 500 fund increases a concentration you already have.

2. S&P 500 UCITS ETFs compared

Data checked on 28 Sept 2026 against each issuer's product page and justETF. TER is the ongoing charge; it does not include broker commissions, spreads or custody fees. Links go to our page for that product where one exists.

The popular US-listed VOO is not on this list: EU retail investors generally cannot buy it.

3. Why swap-based S&P 500 ETFs have tracked better

The index return used for comparison already deducts 15% withholding tax on dividends. A physical Irish ETF pays that tax too, and then recovers some of the gap with securities lending — hence its small positive figure. A swap-based ETF receives the index return from its counterparty without that US withholding tax at all, so on a dividend-paying index it comes out ahead:

Fund return minus index return, in percentage points, per calendar year; positive means the fund did better than its index. Source: trackingdifferences.com, rounded to 0.1. Past tracking does not guarantee future tracking.

Half a point a year is real money over decades. The trade-off is that a synthetic ETF depends on a swap counterparty and on a tax treatment that could change; UCITS rules cap and collateralise that exposure, but it is a different thing to own.

4. S&P 500 index funds (non-ETF)

The option for investors in Spain who want tax-free switching. Check which share class your platform actually sells.

Ongoing charges from each issuer. Fidelity S&P 500 Index Fund is left out until checked against its KID.

5. So, which is the best S&P 500 ETF?

• Lowest running cost with physical replication: SPDR (0.03%), then iShares CSPX and Vanguard VUAA (0.07%). The last two are the largest and most liquid.
• Best historical tracking: the swap-based Invesco, by about 0.2–0.3 points a year over the physical ones in 2023–2025.
• Want dividends paid out: Vanguard VUSA.
• Investing from Spain with contributions and switches: an index fund instead of an ETF.

This is educational content, not financial advice: it explains how these products work so you can make your own decisions, and it does not recommend buying or selling any of them.