Psychologie a chování
Investment Mistake of the Month: Buying a Thematic ETF at the Peak of Hype
Key takeaways
- Buying a thematic ETF after massive media coverage is the classic "late adoption" mistake — you buy once the theme is already priced in.
- The hype cycle works in investing just as it does in technology — after the peak of inflated expectations comes the "trough of disillusionment."
- Thematic ETFs have higher TER and lower liquidity than broad-market funds — the extra cost hurts doubly during a downturn.
- Protection: ask yourself when you first heard about the theme and whether people outside the investment community are recommending it.
- A small long-term satellite position without market timing is a safer approach than a large bet at the peak.
The mistake of the month has a clear face: an investor sees a thematic ETF at the peak of media coverage, builds a large position, and then watches the fund lose a third of its value while the market rises. This is a combination of psychological traps that are perfectly predictable — yet thousands of people fall into them every year.
How the hype cycle works
The consulting firm Gartner popularized the concept of the Hype Cycle for technology — but it applies equally to investment themes. A new topic (AI, metaverse, hydrogen, cryptocurrencies, clean energy...) passes through phases:
- Technology Trigger: first reports, enthusiasm from specialists,
- Peak of Inflated Expectations: media boom, everyone is talking about the new theme,
- Trough of Disillusionment: reality fails to meet expectations, prices fall,
- Slope of Enlightenment: real applications develop more slowly,
- Plateau of Productivity: lasting value — but at far lower valuations than at the peak.
The retail investor who arrives at the Peak of Inflated Expectations buys expensive and holds through the Trough of Disillusionment.
Why this is psychologically so hard
FOMO (fear of missing out) is powerful. When all media and friends talk about how AI or clean energy "will change the world," the brain registers not investing as a mistake. Add availability bias (the easy availability of information about the topic signals its importance) and social proof (everyone else is doing it, so it must be right) and you have a recipe for a bad decision. For a deeper look at the psychology of investing, see the article on risk and how to measure it.
Concrete examples from recent history
Clean energy ETFs exploded in 2020–2021 with global focus on the climate theme — then lost tens of percentage points. ARK Innovation (a thematic bet on disruption) gained over 150% during the pandemic, then fell more than 70% from its peak. Metaverse ETFs arrived exactly when Meta renamed Facebook. The pattern is the same every time.
How not to make this mistake
If a theme interests you, start with a small satellite position (3–5% of portfolio) with a long horizon — independent of current sentiment. Do not add after significant gains. Thematic ETFs are additions, not foundations — how to build your first portfolio and why passive investing wins are required reading before making thematic bets.
FAQ
How do I know when I am at the peak of hype?
Several signals: media is full of enthusiastic articles, friends outside the investment community are asking about the theme, new thematic ETFs are being created quickly, and valuations of companies in the sector are well above historical averages.
Are thematic ETFs always a bad investment?
No. The problem is not the thematic ETF as an instrument, but the timing and the size of the position. A small satellite allocation with awareness of the risks and a long horizon can make sense — a large bet at a media peak generally does not.
What should I do if I bought at the peak and the fund has fallen?
First, stop emotional decision-making. Assess whether the fundamentals of the theme have changed or just the sentiment. If you still believe in the long-term story, hold — but do not add just to lower your average price. If you no longer believe in it, realize the loss and learn from it.