Sektory a témata
How Large a Share of Thematic Bets Is Reasonable: Rules for the Satellite Part of a Portfolio
Key takeaways
- The core-satellite strategy divides a portfolio into a core (cheap global index) and satellites (thematic, sector or regional bets).
- The satellite portion should not exceed 10–20% of the total portfolio — the more themes, the less each one should represent.
- Adding many thematic funds does not create diversification, but a more expensive variant of a broad-market index.
- Evaluate each thematic bet: why this theme, why now, what is the exit plan?
- Regularly reassess whether the thematic story still holds — or whether you are anchoring to a sunk cost.
The core-satellite strategy is a way to add thematic or sector bets to a portfolio without abandoning the diversification foundation — the core is a cheap global index, the satellites are supplements with higher risk and potential.
What core-satellite means
The core represents 80–90% of the portfolio in a cheap, diversified index ETF — for example a global All World or S&P 500. The satellites are the remaining 10–20%: thematic ETFs on a specific sector, a regional bet, alternative assets. The core stabilises, the satellites may generate alpha — or a loss.
How many thematic bets are reasonable
- One bet, 10–15%: concentrated but manageable risk
- Two to three bets, 5–7% each: spread out, but each still meaningful
- Five or more bets at 2–3% each: administrative complexity with no added value; a broad-market index is cheaper
Adding five sector ETFs creates nothing other than a more expensive, less diversified copy of the global index — with a higher TER and a rebalancing burden.
When thematic ETFs make sense
If you have a specific conviction about a long-term trend (demographic ageing, energy transition), a thematic ETF allows you to make that bet without having to pick individual companies. You must be able to endure the volatility, though: thematic funds can drop 50–60% while a global index drops 20–30%. For an overview of ETF segments, visit the ETF Navigator.
Relationship to other articles
The fundamentals of passive indexing are explained in active vs. passive investing. Core options are compared in All World vs. S&P 500. Thematic sectors — genomics, gaming, energy — are covered in other articles in the Sectors and Themes cluster.
FAQ
What is the core-satellite strategy?
A split of the portfolio into a stable core in a cheap global index (80–90%) and a smaller satellite portion in thematic or sector ETFs. The core diversifies and stabilises; the satellites bring a targeted bet with higher risk.
How much of a portfolio should go into thematic ETFs?
The general rule is a maximum of 10–20% of the total portfolio. If you have multiple themes, each should have a meaningful share (at least 5%) — otherwise the administrative complexity outweighs the benefit.
When should you stop holding a thematic ETF?
When the original investment story has fundamentally changed or has become consensus (and valuations reflect it), or when the position is too large for your volatility tolerance. Having exit criteria in advance matters more than intuition.