You Bought a FTSE 100 Tracker and Got 3 Banks, 2 Oil Majors, and a 45% Bet on 10 Stocks — That's Not Diversification, It's Surrender

Market-cap weighting — the default for virtually every tracker fund — means the biggest companies get the biggest allocation. This sounds reasonable until you examine what it produces in practice:

• FTSE 100: Top 10 holdings = ~45% of the index. BP and Shell alone = ~9%. If oil prices crash, your tracker doesn't care — it keeps buying them at their new, larger weight after the crash.
• S&P 500: Top 10 holdings = ~36%. Apple, Microsoft, Nvidia, Amazon — all tech, all correlated. Your global equity fund is 65%+ US stocks, and a chunk of that is seven megacap tech names.
• MSCI World: 70%+ US stocks by weight. The "world" in your global tracker is mostly America.

The FTSE Russell factsheet for the FTSE 100 updates constituent weights quarterly. Check it — the concentration has been increasing for a decade, not decreasing. In 2014, the top 10 were ~38% of the index. Today they're ~45%. Passive investing isn't diversifying you — it's concentrating you further every year.

An index fund buys more of what's already expensive and less of what's cheap. It's a momentum strategy disguised as passivity. When Tesla joined the S&P 500 in December 2020, trackers bought it at the peak of a 700% rally. Active managers had the option — the choice — to say "not at that price."

The SPIVA scorecard says 89.3% of UK equity funds underperformed over 10 years. Let's take that at face value. It means 10.7% did outperform. How do you identify them?

By looking at what they have in common: low turnover, high active share, and — critically — low fees. The Investment Association's data shows that the cheapest quartile of active funds (OCF below 0.50%) have a far better track record than the expensive ones. A Terry Smith or Nick Train doesn't charge 0.75% and trade 120% of the portfolio each year. They charge 0.50-0.65%, hold 25-35 stocks, and turn over 10-15% annually.

"Active management" as a category includes high-turnover closet trackers charging 1.5% for what is essentially an index fund with a marketing budget. Strip those out — and yes, you absolutely should — and the remaining genuinely active, concentrated, low-turnover funds paint a different picture. The FCA's asset management market study identified closet trackers as a specific consumer harm — funds charging active fees for passive-like performance. The regulator explicitly called this out. You can avoid it by checking a fund's active share on its factsheet.

The Bank Rate at 3.75% also changes the calculus. When cash earned nothing, the "just buy the index" argument was stronger — equities were the only game in town. Now, risk-free cash in a cash ISA at 4.51% actually competes. An active manager who can navigate the transition from free money to 3.75% rates earns their fee not through stock-picking alone but through capital preservation — something an index fund never attempts.

The 2026/27 tax year brings a dividend tax rate of 10.75% at basic rate and 35.75% at higher rate — with only a £500 dividend allowance. For a higher-rate taxpayer with investments outside an ISA or SIPP, this is punitive.

An index tracker pays whatever dividends its constituent companies declare, on whatever schedule they declare them. An active manager with a tax-aware mandate can manage this: deferring income, harvesting capital gains within the annual exempt amount (£3,000 for 2026/27), and favouring total return over distributable income.

Consider a £150,000 general investment account holding a FTSE 100 tracker yielding 3.5%. That's £5,250 in dividends. After the £500 allowance, £4,750 is taxable at 35.75% = £1,698 in dividend tax. Every year. An equivalent active fund yielding 2.5% with a focus on capital return cuts that bill to £893 — an annual saving of £805 that partially offsets the fee difference.

For more on tax-efficient investing, our guide to income tax rates and allowances and our ISA hub cover the wrappers that can shield you from this entirely.

Long-dated UK gilts yield 4.94% as of May 2026, per FRED data on the IRLTLT01GBM156N series. This is the highest sustained level in over 15 years. When the risk-free rate is nearly 5%, the equity risk premium — the extra return you demand for taking stock market risk — needs to be substantial to justify equity exposure at all.

An index tracker cannot respond to this. It cannot decide that, at current valuations, the additional 2-3% expected equity return isn't worth the volatility. It buys stocks at whatever price the market sets, forever.

An active manager can say: gilts at 4.94% offer a better risk-adjusted return than the FTSE 100 at a cyclically-adjusted P/E of 16x. I'll hold 20% in gilts, 60% in carefully selected equities, and 20% dry powder for when the opportunity arises. An index tracker holds 100% equities, always. In a world where the risk-free rate has gone from 0.10% (March 2020) to 3.75% (December 2025), that rigidity is a liability, not a feature.

The ONS data on CPI — still above the 2% target through early 2026 — means real gilt yields remain positive but compressed. An active manager who can tilt toward inflation-resistant equities while holding a meaningful gilt allocation is doing something a tracker structurally cannot.

The debate shouldn't be active vs passive. It should be good investment process vs bad investment process. A 0.07% FTSE 100 tracker is a good process. A 1.5% closet tracker with 95% R-squared to the index is a bad process — and a dishonest one. A 0.55% concentrated global equity fund with high active share, low turnover, and a 15-year track record of 2%+ annual outperformance? That's also a good process — and one that 10.7% of active funds demonstrate is achievable.

The FTSE 100 has returned 7.2% annualised over 40 years. That's the benchmark. An active fund charging 0.55% needs to deliver 7.75% to match it after fees. Funds like Fundsmith Equity have delivered 12%+ annualised since inception — not by trading furiously, but by buying 25-30 high-quality companies and mostly leaving them alone.

Index concentration isn't just a UK problem. The MSCI World Index factsheet shows US stocks at 70%+ of the index — up from under 50% in 2010. Your "global" tracker is a bet on American exceptionalism continuing indefinitely. Maybe it will. But you should at least know that's the bet you're making.

This isn't an argument for paying 1.5% for underperformance. It's an argument against the lazy conclusion that "active never works" — a conclusion that itself is a form of active decision-making (you're actively choosing to accept market-cap weights) dressed in passive clothing.