Passive Investing Has a Concentration Problem — Why Smart Active Management Still Earns Its Fee

Buy the Vanguard FTSE Global All Cap — the UK passive investor's default choice — and you get 7,400 stocks. Sounds diversified. Look closer.

Apple, Microsoft, Nvidia, Amazon, Alphabet, Meta, and Tesla together account for roughly 20% of the fund's value. Your "global" tracker is one-fifth US Big Tech. If the AI spending cycle reverses, if US antitrust action bites, if the dollar weakens further — and it fell meaningfully against sterling in 2025 — your diversified portfolio takes a concentrated hit.

Terry Smith — who returned just 0.8% in 2025 versus 12.8% for the MSCI World — made exactly this point in his annual letter. The index's return came overwhelmingly from the same handful of mega-caps. If you weren't in those specific stocks at those specific weights, you underperformed. That's not a skill deficit. That's an index that's stopped functioning as a broad market measure.

The FCA's Consumer Duty rules require platforms to demonstrate that products deliver fair value. A tracker fund that loads 20% of your money into seven stocks and calls it "global diversification" deserves scrutiny under that framework.

Passive investors are paying 0.23% to own this concentration. Active managers who recognise the risk and position around it are charging 0.75% to avoid it. In a year when concentration unwinds, that fee difference pays for itself many times over.

The blanket claim that "passive beats active" obscures enormous variation by market segment. The SPIVA Europe Mid-Year 2025 Scorecard shows that while active managers struggle in large-cap developed markets — where information is priced efficiently and quickly — the picture shifts in less efficient corners.

UK small-caps are a genuine bright spot. Active managers in this space consistently show higher hit rates because the FTSE Small Cap index includes companies with minimal analyst coverage, poor liquidity, and governance issues that a tracker fund must own regardless. A skilled manager can avoid the dross.

Emerging market equities tell a similar story. Corporate governance varies wildly, accounting standards differ, and information asymmetry is real. A tracker fund owns everything — including state-owned enterprises run for political rather than shareholder interests.

UK corporate bonds and strategic bond funds also reward selectivity. With gilt yields at 4.43% and credit spreads widening in early 2026 amid the Iran conflict and oil at $110, knowing which corporate bonds to avoid matters more than broad market exposure. For investors considering the bond allocation, gilts are now paying 5% — here is how to actually buy them covers the mechanics of building a direct gilt ladder or using a bond fund. The Bank of England's latest Financial Stability Report flagged increased corporate default risk in energy-exposed sectors — exactly the kind of risk an active manager avoids and a tracker fund swallows whole.

For investors building a portfolio through their stocks and shares ISA or pension, a blended approach makes more sense than the pure passive dogma suggests. The gov.uk ISA guidance confirms the £20,000 annual allowance — too valuable to waste on a one-size-fits-all strategy when targeted active allocation can add measurable value in specific sectors.

Index funds have a dirty secret: they buy high and sell low by design.

When a stock rises enough to enter an index — or increases its weighting — every tracker fund in the world must buy it at its newly elevated price. When a stock falls out of an index, every tracker sells at the depressed price. This mechanical buying and selling creates a permanent drag that doesn't show up in the OCF.

Academic research has documented this "index inclusion effect" — stocks systematically outperform just before they're added to major indices and underperform after. Tracker fund investors are systematically late to every trade.

Active managers can position ahead of index changes, avoid overpaying for recent index additions, and buy high-quality stocks that have fallen out of an index at precisely the moment they're cheapest. This isn't stock-picking genius — it's avoiding a structural flaw in passive investing that gets worse as more money flows into trackers.

With passive funds now holding over 50% of US equity assets for the first time, this mechanical effect is amplifying. The more money that goes passive, the more mispricing active managers can exploit. The FCA's market oversight division has begun examining whether passive concentration creates systemic risk — a question that would have seemed absurd ten years ago but looks increasingly urgent.

Most active managers don't deserve their fees. The 24% success rate from AJ Bell's data is damning — but it also means roughly one in four does outperform over a decade. The skill is identifying them in advance, not in hindsight.

Three filters that actually work:

High active share: Funds that genuinely differ from the index — holding fewer than 50 stocks, or with less than 60% overlap with the benchmark. If your "active" fund holds the same 100 stocks as a FTSE 100 tracker in slightly different weights, you're paying active fees for a closet tracker. Avoid. The FCA cracked down on closet trackers in its 2018 Asset Management Market Study — but many still slip through.

Manager ownership: Does the fund manager invest their own money in the fund? Fundsmith's Terry Smith has over £200 million of his own money in Fundsmith Equity. That alignment matters — even when the fund underperforms, you know the manager is feeling the same pain.

Fee discipline: The best active funds charge under 0.5%. Anything above 1.0% is indefensible in 2026. Look at investment trusts — Finsbury Growth & Income, for example, charges 0.57% and has outperformed the FTSE All-Share over most long-term periods.

For tax-efficient investing, an active manager who generates fewer taxable events through lower turnover can actually save money compared to a tracker that must trade mechanically. If your instinct is still toward the safety of cash, why your cash ISA is costing you a fortune puts concrete numbers on that drag. Inside an ISA wrapper this advantage disappears, but in a general investment account it's meaningful. Check our savings hub for how platform choice interacts with fund selection on after-tax returns.

The debate is a false binary. The optimal UK portfolio in 2026 uses both. (If you've read the other side of this argument — why 76% of active managers lose to a tracker — you'll see why blending, rather than choosing, makes sense.)

Use passive for the core — 60-80% of your portfolio in low-cost global trackers where active managers struggle to add value. The Bank of England base rate at 3.75% and inflation at 3% mean the real return hurdle for equities is modest — a cheap global tracker clears it comfortably.

Use active for the satellites — 20-40% in areas where information asymmetry creates genuine alpha opportunities: UK small-caps, emerging markets, strategic bonds, and specialist sectors like infrastructure or renewable energy where UK-listed investment trusts have genuine expertise.

This isn't a compromise. It's the strategy that the most sophisticated institutional investors — endowments, pension funds, family offices — have used for decades. They don't go 100% passive or 100% active. They allocate cheap beta exposure through index funds and pay up for genuine skill where it exists.

With the ISA deadline approaching and markets rattled by $110 oil and geopolitical uncertainty, the last thing you want is 100% of your wealth riding on a mechanical index that's 39% concentrated in ten stocks. A thoughtful blend of passive and selective active gives you diversification that pure passive no longer provides. MoneyHelper's investing guidance sensibly suggests considering a mix — the question is getting the proportions right for your risk tolerance and time horizon.

For a deeper look at which investment platforms best support a blended active-passive strategy, and how to compare platform fees at different portfolio sizes, see our ISA comparison guide.

This article is for informational purposes only and does not constitute financial advice. You should seek independent financial advice before making any investment decisions.