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InvestingYou can hold 500 companies and still be concentrated in one sector. This UK guide covers common sector traps, how to check your exposure, and how to fix it.
Reviewed July 2026 · Reading time: ~9 minutes
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You can hold hundreds of companies and still be badly concentrated — if they're all in the same sector. Sector concentration risk means a portfolio's returns are dominated by the performance of one industry rather than the broad economy. Common UK examples: FTSE 100 (heavy in financials + oil), FTSE All-Share (still finance-heavy), S&P 500 (increasingly tech-heavy).
Roughly 20% of the FTSE 100 is financial services (banks, insurers). Buy an FTSE tracker and 20% of your money moves with UK bank earnings and regulation. In 2008 this hurt badly. Global trackers dilute this to 15% or less.
The S&P 500 is now roughly 30% technology-adjacent. Adding to that with an "S&P 500 ETF" plus a "Global Tech ETF" plus "Nasdaq 100" quickly puts 60%+ of your portfolio into one sector.
Clean energy + AI + robotics + electric vehicles + biotech — each pitched as separate diversification, but they often hold overlapping companies (Tesla, Nvidia appear everywhere). Portfolio ends up highly concentrated in a small number of names.
Every fund publishes sector weights in its factsheet. Add them up across your holdings, weighted by how much of each fund you own. A well-diversified portfolio might look like:
| Sector | Global cap-weighted portfolio % |
|---|---|
| Technology | ~24% |
| Financials | ~15% |
| Healthcare | ~11% |
| Consumer discretionary | ~11% |
| Communication services | ~8% |
| Industrials | ~10% |
| Consumer staples | ~7% |
| Energy | ~4% |
| Materials | ~4% |
| Utilities | ~3% |
| Real estate | ~3% |
Any sector over 25-30% of your portfolio is concentration you should be aware of. Over 40% is genuinely risky.
Global ETFs (VWRP, SWDA) diversify across sectors naturally because they hold every sector's largest global players. Regional trackers (FTSE 100, FTSE All-Share) inherit the sector bias of that market — FTSE 100 is finance + oil + mining heavy, not tech.
Building a UK portfolio purely from FTSE 100 trackers gives you a wildly different sector exposure from a global portfolio. Neither is inherently wrong, but you should know which you have.
VWRP or SWDA reflects the global sector split naturally. Simplest way to avoid sector traps.
Instead of cap-weighting, equal-weighted funds hold each company at the same weight. Reduces concentration in mega-caps. OCFs slightly higher (0.20-0.30%).
Hold a global core (80% VWRP) plus small tactical allocations to underweight sectors (10% healthcare ETF, 10% dividend/value ETF). Structured tilting rather than accidental concentration.
Add a small-cap ETF alongside a large-cap tracker. Small-caps are underrepresented in cap-weighted large-cap indices.
Accidentally concentrated portfolio: Invest in VWRP (24% tech) + Nasdaq 100 (60% tech) + Global Tech ETF (100% tech). Effective tech weight: over 50% of portfolio. High single-sector risk.
Well-diversified portfolio: Invest in VWRP alone. Tech weight: 24%. Financials: 15%. Everything else: reasonably spread.
Home-biased UK portfolio: 50% VWRP + 50% ISF (FTSE 100). Combined sector weights: Financials +20% (mostly UK banks), Energy +10% (BP, Shell). Very different from cap-weighted.
Cap-weighted global exposure is currently ~24% tech. Above 40% starts to look like a sector bet rather than diversified investing.
By company count yes (100). By sector, no — heavily concentrated in financials, oil, mining, and consumer staples. Very different sector mix from a global tracker.
Usually not. Thematic ETFs typically concentrate rather than diversify — they hold overlapping companies with your existing holdings.
Yes — the US is ~60% of global cap-weighted equities. If that concerns you, options include equal-weighted funds, or non-US regional funds to rebalance.
Annually is enough. Sector weights drift as markets move, but the drift is usually small over 12 months.
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