Start with the job, then pick the cheapest fund that does it well.
1. **One-fund core.** If you want simplicity, a single global all-world fund (Vanguard FTSE All-World, or the cheaper SPDR ACWI IMI) is a complete portfolio on its own. This is the right answer for most people.
2. **Two-fund control.** If you want to set your own emerging-markets weighting, pair a developed-world fund (Vanguard FTSE Developed World at 0.12%) with an emerging-markets fund (iShares EMIM at 0.18%) and blend them yourself.
3. **Satellite tilts.** S&P 500, Nasdaq-100 and FTSE 100 funds are single-country or single-region bets. They can sit alongside a global core as a small deliberate tilt, but they are not diversified portfolios in their own right. Cheap does not mean safe.
4. **Bonds and income.** A global bond fund (hedged to sterling) dampens volatility for those closer to needing the money; a high-dividend fund suits investors who specifically want income. Neither is essential for a young investor with a long horizon.
The through-line: the broad, cheap, boring global tracker beats the clever expensive bet for the overwhelming majority of investors, because you keep the fee saving for certain and nobody can promise the clever bet will pay off. The
one global tracker piece makes the full case, and our
low-cost index funds guide lists the specific tickers. If you want a single satellite US fund, the
best S&P 500 ETF UK comparison drills into VUAA, CSPX and the rest.