Core and Satellite: Keep Most of Your Money Boring and Play With the Rest
6 min read
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6 min read
You have Rp100 million to invest. Part of you wants a calm index fund. Another part wants to try a hot sector, a single stock or some crypto.
Do you have to pick one? No. A core satellite portfolio lets you do both. Most of your money stays in the boring part. A small slice is set aside for the fun part. This post shows how that works, with real arithmetic, and where it can go wrong.
Picture a planet with a few small moons.
The core is the planet. It is the big, steady base of your portfolio. Sources describe it as low-cost, widely spread holdings such as index funds, ETFs and investment-grade bonds. An index fund is a fund that copies a market index, like the IDX30, instead of trying to beat it. An ETF is a fund that trades on the stock exchange like a share.
The satellites are the moons. They are smaller positions where you take a deliberate view. That could be one sector, one theme, a few single stocks or crypto.
Betashares, an Australian fund manager, puts the idea this way. The core aims to earn the market return. The satellites aim to beat it. Whether they actually do is a different question, and we come back to it below.
There is no official split. Sources disagree, and that is worth knowing.
| Source | Core share | Satellite share |
|---|---|---|
| TMX | 60% to 80% | 20% to 40% |
| My ETF Journey | 70% to 90% | 10% to 30% |
| ClearTax | 80% to 85% | 15% to 20% |
These ranges come from search result summaries of each page, retrieved on 10 October 2026. None of them calls one split the standard. A common thread is that people who dislike risk keep a bigger core.
For the rest of this post we use 80/20. It is an example, not advice.
Here is NetWort's own arithmetic. The returns are invented to show the shape of the idea. They are not forecasts.
You put Rp80 million in the core and Rp20 million in satellites. Say the core earns 8% over a year. That is Rp6.4 million.
Now three things the satellite could do:
| Satellite result | Satellite ends at | Core ends at | Whole portfolio | Return |
|---|---|---|---|---|
| Rises 50% | Rp30 million | Rp86.4 million | Rp116.4 million | +16.4% |
| Falls 40% | Rp12 million | Rp86.4 million | Rp98.4 million | -1.6% |
| Falls 100% | Rp0 | Rp86.4 million | Rp86.4 million | -13.6% |
Look at the last row. Even if the satellite goes to zero, you lose 13.6%, not 100%. You lose Rp13.6 million of your return, not your whole Rp100 million. The core carries the weight.
Look at the first row too. A 50% win in a 20% slice lifts the whole portfolio by 10 points. The bet matters, but it does not decide everything.
Now compare with putting all Rp100 million in the core, which earns the same 8%. You end at Rp108 million.
| Plan | If satellite rises 50% | If satellite falls 40% |
|---|---|---|
| All in core | +8.0% | +8.0% |
| 80/20 core and satellite | +16.4% | -1.6% |
The all-in-one plan is boring and steady. The 80/20 plan wins big when the bet works and loses a little when it does not.
Notice what the table does not show. It does not say the satellite will win. It only shows the price of trying. In the second column, that price is 9.6 points of return (8.0% minus -1.6%).
Often they do not. This is the honest part of the strategy.
Satellites add risk and can add cost, as one South African broker's guide notes. Fees on active funds, trading costs and taxes all eat into gains. If your satellite picks do not beat the market over time, the 20% slice is just a more expensive way to hold the market.
That is why many people treat the satellite as a learning budget or a fun budget. It is money you can afford to be wrong with. For ideas on how closely a fund should copy its index, see our tracking error explainer.
Prices move, so your 80/20 will not stay 80/20.
Take the first row from the table. The satellite grew to Rp30 million out of Rp116.4 million. That is now about 25.8% of your portfolio, not 20%. Your risk has crept up without you doing anything.
To fix it, you rebalance. That means selling a bit of what grew and adding to what lagged, until you are back at your target. We compare two ways to do it in calendar vs threshold rebalancing.
A simple rule many people use is to check once or twice a year. Pick a rule before you start, so you do not decide in the heat of a rally.
A few habits keep a satellite from taking over:
Can you tell which of your holdings are your core and which are your satellites?
Open Holdings in NetWort. Mark your broad index funds or ETFs as one group in your head, and everything else as the other. Then add up each group as a share of the total. If your "satellite" is far bigger than you thought, you have found something worth fixing.
For the market and rate backdrop that moves your core, see the macro page.