Core-Satellite Strategy Explained Simply
September 5, 2026
5 min read
- Core-satellite splits a portfolio into a broad, cheap core and targeted additions. The core delivers the market return; the satellites are a deliberate deviation from it.
- A market-cap-weighted world index is broad but not free of concentration. A handful of very large companies dominate it today.
- Both directions are defensible: the index as core with a concentrated addition — or a concentrated quality portfolio as core with the index broadening it.
Diversification by count is not the same as diversification by risk. That distinction is exactly where core-satellite begins.
The idea comes from institutional asset management and has become practical for private investors too: a portfolio consists of a broad, low-cost core and a few targeted additions. It sounds simple — the interesting questions sit in the weighting.
01The basic idea
The core is the part that represents the market: broadly diversified, cheap, rules-based and without an opinion. It typically takes the larger share of the portfolio and is left alone.
The satellites are deliberate deviations from the market. That might be a concentrated equity portfolio, a regional or thematic tilt, or an asset class the core does not cover. They take a smaller share and have a clear purpose.
The condition most people fail: every satellite needs a reason beyond "it performed well recently". Without that reason it is not a satellite, it is an accumulation. A good test: can you say in one sentence what this position does that your core does not?
02Why the question arises at all
A world index such as the MSCI World holds over 1,480 companies — that sounds like maximum diversification. But because it is weighted by market capitalisation, its result depends disproportionately on a few very large companies. When they rise, the index rises. When they fall, the large number of remaining positions helps little. Concretely: the ten largest positions in an MSCI World product account for roughly a quarter of fund assets — out of more than 1,480 companies held.
Add to that a regional and sector concentration: the US share of a developed-markets index is high, and a substantial part of that sits in a single sector. If you see that as a risk, you have two options — accept it, or counteract it deliberately.
03Version A: the index as core
The classic split. A broad world index forms the core, with concentrated or specialised positions added as satellites.
In favour: the core is maximally cheap and maximally broad. Mistakes in the satellites have limited impact. And the structure is easy to explain — which matters more in difficult markets than it sounds.
Against: the core carries the index's concentration risks unchanged. Reducing them means building substantial weight in the satellites — at which point calling them satellites no longer fits.
04Version B: a concentrated quality portfolio as core
The reverse split, discussed less often and still coherent. A concentrated portfolio of selected quality businesses forms the core; the world index is layered on top as broadening.
In favour: an actively constructed portfolio can be deliberately less dependent on individual very large names, on one region or on one sector than the index is. If your main criticism of the index is that concentration, this addresses the problem at the centre rather than at the edge.
Against: concentration means a wider spread of outcomes and dependence on the quality of selection. And it costs more than an index product.
What applies in both versions: a concentrated portfolio belongs inside a total wealth picture, not beside it. As a sole position it is not a strategy but a bet. And both versions ultimately combine the same two things — market return and active selection. They differ only in weighting.
How we handle it ourselves: the arvy ETF Savings Plan tracks the world index and delivers the market return. The arvy fund is a concentrated portfolio of selected quality businesses, deliberately composed differently from the index. Both orderings are defensible — index as core with the fund alongside, or the reverse. What we do not recommend is the fund as a sole position.
05How to choose the weighting
There is no universally correct split, but three useful questions.
How much deviation can you tolerate? A concentrated portfolio will underperform the index at times, and those periods can last years. The question is not whether you expect them, but whether you can sit through them.
How much effort do you want? More building blocks mean more monitoring, rebalancing and tax reporting. For many people a single core without satellites is the most honest answer.
What is each position for? If you cannot state it in one sentence, it does not belong in the portfolio. More on this in The 7 Most Common Savings Plan Mistakes.
06Frequently asked questions
What does core-satellite mean?
A portfolio structure with a broad, cheap core delivering the market return, plus smaller targeted additions that deliberately deviate from the market. The core stays untouched; the satellites have a defined purpose.
How large should the satellite share be?
It depends on risk tolerance and horizon. What matters is that a weak period in the satellites does not damage the overall result enough to make you abandon the strategy.
Isn't a world index already diversified enough?
By number of companies, yes. But because it is weighted by market capitalisation, its result depends disproportionately on a few very large names and on individual regions and sectors.
Can an active fund be the core?
Yes, if it is broad enough and you want the deviation from the index deliberately. What matters is the total picture: a concentrated portfolio should not be someone's only position.
How often should I rebalance between core and satellite?
Once a year is usually enough, or when the target weighting is clearly exceeded. More frequent switching creates transaction costs and systematically cuts good developments short too early.
Does Pillar 3a count towards the core?
From a total wealth perspective, yes. Treating Pillar 3a, the pension fund and an unrestricted portfolio separately makes concentrations easy to miss — for example a already high Swiss allocation from pensions that makes an extra home tilt unnecessary.
Are gold or cryptocurrencies satellites?
They are often used that way. Neither produces ongoing income, however, so the expectation rests entirely on price. If you add them, you should be able to name the purpose and keep the position small enough to sit through.
07Keep reading
Overview
How to build the core of a portfolio in practice.
Core and satellite from one place
The ETF Savings Plan for market return, the arvy fund for concentrated quality.
arvy ETF Savings Plan
0.39% management plus 0.06% TER on the world equity portfolio, broad world index, invested weekly.
To the savings plan →This article was written by Thierry Borgeat, co-founder of arvy, and reviewed by Patrick Rissi, CFA, and Florian Jauch, CFA.
Disclaimer: arvy AG is a manager of collective assets authorised by the Swiss Financial Market Supervisory Authority FINMA under Art. 24 of the Collective Investment Schemes Act (CISA). This article is for information purposes only and constitutes neither investment advice nor tax or legal advice, nor an offer or solicitation to buy or sell financial instruments. The calculations shown are model calculations based on the stated assumptions and are not forecasts; they assume a constant return compounded monthly at the stated nominal annual rate. Past performance is not a reliable indicator of future results. Equity investments are subject to price fluctuations; losses up to the total loss of the capital invested are possible. Tax consequences differ by canton and by individual situation — please clarify yours with a professional.
