Best S&P 500 Index Funds 2025: Low-Cost & How to Buy

You’ve probably heard the advice: buy the S&P 500 and hold it, but figuring out exactly which fund to pick, how to buy it, and whether the numbers really work for you can feel like a maze. This guide cuts through the noise, compares the lowest-cost funds available, and shows you what a $10,000 investment would look like over two decades—with a special focus on the options for Irish investors.

Cheapest S&P 500 ETF TER: 0.07% (iShares Core S&P 500 UCITS) ·
Largest S&P 500 UCITS ETF AUM: €131.6 billion ·
Irish-domiciled UCITS ETFs: Yes, multiple options

The table below consolidates key facts about the leading S&P 500 funds.

What is the best S&P 500 index fund?

Three funds dominate the conversation for non-US investors, each with a different sponsor. The table below shows the ones with the lowest costs and broadest availability.

All three carry the same expense ratio, so the best pick often comes down to which broker you use and whether you prefer accumulating or distributing dividends. justETF (ETF database) notes that CSPX is the largest ETF tracking the S&P 500 index, which can mean tighter bid-ask spreads when trading.

Lowest cost S&P 500 index funds compared

• iShares Core S&P 500 UCITS ETF – TER 0.07% (justETF (ETF database))
• Vanguard S&P 500 UCITS ETF – TER 0.07% (Vanguard UK Professional)
• SPDR S&P 500 UCITS ETF – TER 0.07% (State Street Global Advisors)

Vanguard vs Fidelity vs Schwab S&P 500 funds

For US-based investors, Vanguard, Fidelity, and Schwab offer their own S&P 500 index funds at ultra-low costs. The table below shows the fee race.

Fidelity’s expense ratio is the lowest among the three, but the differences are tiny. The implication: choose the fund from the brokerage you already use to avoid transaction fees.

How to buy S&P 500 in Ireland?

Irish investors cannot buy US-listed ETFs directly because of EU regulatory restrictions. Instead, they use UCITS-compliant ETFs that are domiciled in Ireland and trade on European exchanges. According to a step-by-step guide on investing from Ireland, the process is straightforward once you open a broker account.

Using Degiro or other European brokers

1. Open an account with a broker like Degiro, Interactive Brokers, or Revolut.
2. Search for the UCITS ETF you want (e.g., CSPX, VUSA, SPY5).
3. Check whether the ETF is commission-free on your platform’s core selection.
4. Place a buy order for the desired number of shares or a set amount.

Best S&P 500 ETFs for Irish investors

• CSPX (iShares) – accumulating, no dividend tax drag
• VUSA (Vanguard) – distributing, pays quarterly dividends
• SPY5 (SPDR) – distributing, lower dividend yield

Accumulating versions like CSPX are popular because they reinvest dividends automatically, which simplifies tax reporting. No Money Lah personal finance blog notes that Ireland-domiciled UCITS ETFs are the standard route for non-US investors.

Tax considerations for Irish residents

• ETFs are subject to deemed disposal every 8 years – you pay tax on unrealised gains
• Income tax rate of 41% on gains, plus PRSI and USC
• Dividends are taxed as income

What if I invested $10,000 in the S&P 500 20 years ago?

If you had put $10,000 into the S&P 500 in 2004 and reinvested dividends, by the end of 2024 that investment would have grown to roughly $52,000. That’s an average annual return of about 8–10% – a solid result for a passive strategy.

Historical S&P 500 returns over 20 years

• 2004: index at ~1,200
• 2008–2009: –38% during the financial crisis
• 2014: +13.7% for the year
• 2020: COVID-19 crash followed by rapid recovery
• 2024: record highs above 5,800

How compounding works with index fund investing

Compounding is the engine: reinvested dividends buy more shares, which then earn dividends themselves. The iShares Core S&P 500 UCITS ETF (CSPX) launched in 2010 and has since grown to €131.6 billion in assets (justETF (ETF database)).

What S&P 500 fund does Warren Buffett recommend?

Warren Buffett has repeatedly said that most investors – including his own estate – should put 90% of their money into a low-cost S&P 500 index fund and 10% into short-term government bonds. He specifically recommended the Vanguard 500 Index Fund (VFIAX) in his 2013 letter to Berkshire Hathaway shareholders.

Warren Buffett’s advice to his trustee

• “Put 90% of the inheritance in a very low-cost S&P 500 index fund”
• Remaining 10% in short-term government bonds
• He believes active management rarely beats the market over the long term

Comparison of Vanguard 500 Index Fund vs others

VFIAX has an expense ratio of 0.04%, which is higher than Fidelity’s FXAIX (0.015%) but still extremely low. The key difference: Vanguard is owned by its fund shareholders, so profits are returned to investors in the form of lower fees.

Should I put $10,000 into the S&P 500?

For a lump sum like $10,000, the historical data favours investing it all at once rather than spreading it out. Research shows that lump sum investing outperforms dollar-cost averaging about two-thirds of the time. However, risk tolerance and time horizon are critical.

Pros of lump sum investing in S&P 500

Cons and risk considerations

Past performance is not a guarantee. The S&P 500 has had negative years – 2008, 2022 – and future returns could be lower. For a 10-year horizon, the risk of a large loss drops considerably. For a 5-year horizon, it’s higher.

Timeline

• 2010 – iShares Core S&P 500 UCITS ETF launched (justETF (ETF database))

The other milestone years (2004, 2008, 2014, 2020, 2024) are commonly cited but not sourced to a single original document. For verified data, refer to the snapshot card above.

Clarity section

Confirmed facts

• iShares Core S&P 500 UCITS ETF has a TER of 0.07% and tracks the S&P 500 by full replication (justETF (ETF database))
• Vanguard S&P 500 UCITS ETF is an Irish-domiciled passive fund (Vanguard UK Professional)
• SPDR S&P 500 UCITS ETF is Ireland-domiciled and registered in multiple European countries (State Street Global Advisors)
• Irish investors can buy S&P 500 ETFs via Degiro, Interactive Brokers, and Revolut (YouTube – step-by-step guide)
• Warren Buffett recommends a low-cost S&P 500 index fund for 90% of an inheritance

What’s unclear

• Which specific fund is “best” depends on the investor’s country and broker access
• Future S&P 500 returns cannot be guaranteed – past performance is not a reliable predictor
• Exact historical index levels (2004, 2008, 2014, 2020, 2024) are not sourced from a single authoritative database in this guide
• Tax rule changes for Irish ETF investors remain uncertain

Quotes

“Put 90% of the inheritance in a very low-cost S&P 500 index fund.”

Warren Buffett, 2013 Berkshire Hathaway annual letter

“Don’t look for the needle in the haystack. Just buy the haystack!”

John Bogle, founder of Vanguard

The wisdom of both investors points to the same conclusion: low-cost index funds are the most reliable path for long-term wealth.

Summary

Low-cost S&P 500 index funds offer a simple, time-tested path to long-term wealth, backed by the endorsement of Warren Buffett and decades of market data. For Irish investors, the choice of UCITS ETFs like CSPX, VUSA, or SPY5 makes it easy to buy in from home. The decision is clear: pick a fund with a TER under 0.10%, open a broker account, and invest consistently – or risk leaving thousands on the table in fees and missed compounding.

Frequently asked questions

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