Chapter 8: Thematic and sector funds
Over the 15 years to mid-2024, roughly 1 in 10 thematic funds managed to do both of the things a fund has to do for you: survive the whole period and beat a plain global stock index. That count comes from Morningstar's research on thematic funds worldwide. The other nine in ten either closed along the way or finished behind the boring alternative their buyers already owned. The aisle keeps growing anyway, because these funds are wonderfully easy to sell, and this chapter is about the machine that sells them.
A thematic fund owns a basket of companies chosen to express one story about the future: robotics, clean energy, space, artificial intelligence, cybersecurity, pet care. The story is usually true, which is exactly what makes the aisle dangerous. Nobody needs a sales pitch for a false story.
The launch machine runs on the rearview mirror
Fund companies decide what to launch by watching what just went up. A theme needs a beautiful 3-year chart before it can be packaged, because the chart is the brochure: the pitch deck, the seminar slide, and the social post are all, at bottom, a picture of the recent past pointed at your future. That sequencing has a built-in consequence. By the time a theme has a chart good enough to sell a fund, a large part of the move that drew the chart has already happened, and the new fund starts life owning companies priced for applause.
So launches cluster late. The fund arrives near the top of the excitement curve, the early buyers arrive just after the fund does, and the years that follow have to carry expectations the chart already spent.
Being right about the technology is not being right about the fund
This is the aisle's central trap, and it deserves its own paragraph because it catches smart people preferentially. The internet really did change everything. Electric cars really are replacing gasoline ones. A theme can be completely, historically correct and its funds can still lose money, because the Stocks Guide's chapter 5 lesson applies to baskets exactly as it applies to single stocks: a price is a bundle of expectations, and a famous future is an expensive future. When you buy the fund, you are paying whatever the crowd already believes the story is worth.
Count what has to go right. The theme must play out in the real world. The specific companies in the basket must be the ones that capture it, which is far from automatic, since theme funds often hold smaller, looser fits because the obvious giants are already classified elsewhere. And those companies must then do better than the price assumed on the day you bought. One purchase, three separate bets, and the roughly-1-in-10 survival-and-win rate over 15 years suggests how often all three land together.
Why do investors in exciting funds earn less than the funds themselves?
Because money tends to arrive after the good years and leave after the bad ones, while a fund's posted return assumes you sat still from the first day to the last.
Morningstar's Mind the Gap study measures the difference. Over the 10 years ending December 2024, the average US fund earned 8.2% a year, while the average dollar invested in those funds earned 7.0% a year. The missing 1.2 points a year is pure timing: buying after the chart turned beautiful, selling after it turned ugly, repeating. And the study's sharpest finding for this chapter is where the gap lives. It concentrates in narrow, volatile funds, which is a fair description of the entire thematic aisle. A broad, dull fund is hard to mistime badly because it rarely does anything dramatic enough to provoke you. A robotics fund that doubles and then halves is a mistiming machine with a ticker.
Sector funds, the milder cousin
A sector fund owns one industry rather than one story: technology, healthcare, energy, financials. Two honest things can be said about them.
They are a legitimate tool. An investor who wants a deliberate, measured tilt toward an industry can get it cleanly, often at index-fund prices, without a narrative attached.
They are also usually redundant. Your total-market fund already owns every sector at its market weight, and the giant technology companies are already its largest holdings. Buying a tech sector fund on top mostly doubles positions you hold, which means more concentration rather than more diversification. The overlap check from Chapter 4's five-line checklist settles this in two minutes: pull the sector fund's top ten holdings and see how many already sit near the top of the fund you own. Most readers will find the answer is nearly all of them.
One more label warning applies to this whole aisle. Under the SEC's Names Rule, adopted in September 2023 and fully in force as of this month, a fund whose name suggests a focus must keep at least 80% of its assets matching that name, reviewed quarterly. Useful, and limited. A name is now a weak promise rather than no promise, and the other 20% is leash. "Robotics" on the label tells you the theme; only the holdings list tells you the fund.
Hugo orders the test, not the fund
Hugo, a dentist with $1.4 million invested, accepted a free steakhouse dinner because the filet was real even if the pitch was not. The product arrived with dessert: a robotics ETF, a 3-year chart pointing at the ceiling, and a line aimed straight at him: "You use robotic equipment in your own practice, doctor. You understand this better than most." Flattery, chart, story, in that order, and he could feel all three working, which is the moment the test below exists for. He asked what the fund charges, and the presenter had to look it up. He asked how many of the fund's top holdings his total-market index fund already owned, and the presenter did not know that either, so Hugo did the checking himself at the table: most of them. He asked his standing first question, what does the seller earn before the buyer gets anything, thanked the room, and declined. The filet, he reports, was excellent.
The test that saved him fits on a card, and it works on any theme fund ever pitched to you.
- What does the seller earn? Find the expense ratio before you hear another word, and compare it with the 0.03% a broad total-market fund charges. The difference is the price of the story.
- Would I want this without the chart? If the 3-year chart is the argument, the argument is the past, and you are being sold a rearview mirror.
- What do I already own? Check the fund's top ten holdings against your index fund. Heavy overlap means paying a premium for companies you hold at 0.03%.
- What has to go right? The theme must win, the basket must capture it, and both must beat what the price already assumed. Say all three out loud.
- Core or explore? If the honest answer is "this is a bet," it goes in the explore sleeve at explore-sleeve size, never in the core.
A theme fund is an explore-sleeve purchase, never a core holding. The Stocks Guide's chapter 13 caps apply unchanged: 5–10% of your investable money for all exploring combined, sized so a total loss changes none of your plans, with the boring index funds doing the actual work underneath.
Where people go wrong
- Buying the chart. The launch machine packages the last 3 years and sells them as the next 10. The chart is what you missed, never what you are owed.
- Confusing the theme with the trade. The technology can win while the fund loses, because the price already believed. Three bets must land, and the long-run base rate is roughly 1 in 10 over the 15 years to mid-2024.
- Becoming the gap. Exciting funds provoke exciting behavior, and the 1.2-point annual gap between funds and their investors lives mostly in this aisle. The posted return belongs to whoever sat still.
- Collecting overlapping funds. Five themed funds holding the same giant companies is one bet wearing five tickers. Run the overlap check before calling it diversification.
- Trusting the label. The Names Rule requires an 80% match, reviewed quarterly, and nothing more. The name is marketing with a floor under it; the holdings list is the fund.
Key takeaways
- Roughly 1 in 10 thematic funds both survived and beat global equities over the 15 years to mid-2024. The other nine in ten closed or lost to the plain index their buyers already owned.
- Thematic funds launch after the run-up, because the run-up is the brochure. New buyers inherit prices already set for applause.
- Being right about the technology is one of three bets. The basket must capture the theme, and the companies must beat what the price assumed the day you bought.
- Investors in US funds earned 7.0% a year against 8.2% for the funds themselves over the 10 years ending December 2024, and the gap concentrates in narrow, volatile funds exactly like these.
- Sector funds are legitimate tilts that usually duplicate your index fund; run the overlap check first. The Names Rule guarantees only an 80% match to the label.
- Themes belong in the explore sleeve, capped at 5–10% of investable money, never in the core.
Sources: Morningstar thematic funds research · Morningstar Mind the Gap · SEC Names Rule press release · Finvest Stocks Guide