Learn Part 6 — How to Invest The S&P 500 — What It Is and Why Everyone Talks About It

Part 6 — How to Invest

Chapter 34 of 40

The S&P 500 — What It Is and Why Everyone Talks About It

500 companies, one number, and why it matters to you

6 min read Beginner

"The S&P 500 is an index of 500 large US companies. When people say "the market is up 2%" they usually mean the S&P 500 is up 2%. Understanding what it is, what drives it, and how to own a piece of it takes about 10 minutes."

For educational purposes only. Nothing in this chapter is financial advice. All figures are illustrative examples. Tax rules, account types, contribution limits, and regulations differ by country and change over time. Always verify current rules with official government sources or a qualified financial adviser before making any investment decisions.

What the S&P 500 Is

The S&P 500 (Standard and Poor's 500) is a market-capitalisation weighted index of the 500 largest publicly listed companies in the United States. "Market-cap weighted" means that larger companies have a bigger impact on the index's performance — Apple, Microsoft, and Nvidia (the top three in early 2025) together represent around 20% of the total index.

The index is maintained by S&P Dow Jones Indices, which decides which companies qualify for inclusion. To be in the S&P 500, a company must be incorporated in the US, have a market capitalisation of at least $14.5 billion, have positive earnings over the most recent quarter and on a cumulative 12-month basis, and have at least 50% of its shares publicly available. Companies are added and removed as conditions change.

The S&P 500 is widely considered the best single benchmark for US stock market performance and, by extension, global equity performance — since the US represents approximately 60–65% of global equity market value.

How to Buy It as a UK Investor

You cannot invest directly in the S&P 500 — it is an index, not a fund. You invest in funds or ETFs that track it. As a UK investor, the most accessible routes are:

iShares Core S&P 500 UCITS ETF (CSP1 / CSPX): The largest S&P 500 ETF available on UK platforms. Expense ratio: 0.07%. Available in ISA and SIPP on most UK brokers including Hargreaves Lansdown, AJ Bell, and Trading 212.

Vanguard S&P 500 UCITS ETF (VUSA): Vanguard's version. Expense ratio: 0.07%. Distributing (pays out dividends) rather than accumulating. Available on most UK platforms.

Both should be held inside a Stocks and Shares ISA where possible to shelter gains from Capital Gains Tax and dividend income from Income Tax. In the UK, US dividends paid through these funds are subject to a 15% US withholding tax, which cannot be reclaimed in an ISA but is already accounted for in fund performance figures.

Historical Returns and Concentration Risk

The S&P 500's historical nominal return is approximately 10% per year since 1957. After inflation (around 3% long-run), the real return is approximately 7% per year. These are averages across decades that include severe crashes (2000–2002: -50%, 2008–2009: -55%, March 2020: -34%) and extended bull markets.

The main risk specific to the S&P 500 is concentration. As of early 2025, the top 10 companies (Apple, Microsoft, Nvidia, Amazon, Meta, Alphabet, Tesla, Berkshire Hathaway, Eli Lilly, JPMorgan) represent approximately 35% of the total index. If these large-cap tech companies underperform or face regulatory action, the index is disproportionately affected compared to a more globally diversified fund.

S&P 500 vs global index: The S&P 500 has outperformed global indices for most of the past 15 years due to US tech dominance. This may continue — or it may not. A global index fund includes the S&P 500 as its largest component (~60%) while also giving exposure to Europe, Japan, and emerging markets.

FAQs

Is the S&P 500 the same as "the market"?

Often used synonymously with "the US market," yes. It represents approximately 80% of total US equity market capitalisation. It excludes small and mid-cap US companies, which are covered by broader indices like the Russell 3000.

Should a UK investor choose the S&P 500 or a global index?

Both are reasonable choices. The S&P 500 has outperformed global indices over the past decade, but this is partly because US tech valuations expanded significantly. A global index is more diversified; an S&P 500 fund is concentrated in a single country. Many investors hold both or use a global fund as their single holding.

What is the currency risk for UK investors?

S&P 500 ETFs are priced in USD. When the pound strengthens against the dollar, your sterling returns are reduced; when the pound weakens, your returns increase. Over long periods, currency effects tend to be secondary to market returns. Hedged versions (with "GBP hedged" in the name) eliminate this but add a small extra cost.

Does the S&P 500 pay dividends?

Yes. The S&P 500's dividend yield is currently around 1.3–1.5%. "Distributing" ETFs pay this out as cash; "accumulating" ETFs reinvest it automatically within the fund (preferable in most cases for long-term growth inside an ISA, as it avoids income tax on dividends received).

Key takeaways

The S&P 500 is a market-cap weighted index of the 500 largest US companies — not a fund you buy directly.
UK investors access it via ETFs like iShares CSP1 (0.07%) or Vanguard VUSA (0.07%), ideally inside a Stocks and Shares ISA.
Historical nominal return: ~10%/year; real (inflation-adjusted) return: ~7%/year over long periods.
The top 10 holdings represent ~35% of the index — concentration in US mega-cap tech is the main risk.
A global index fund gives broader diversification while still having the S&P 500 as its largest component (~60%).