Volatility Drag: Why a Bumpy 10% Beats Nothing but Loses to a Smooth 10%
5 min read
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5 min read
Two investments both average a 10% return a year. You put Rp100 juta in each and wait four years. One ends at Rp146.4 juta. The other ends at Rp92.2 juta, less than you started with.
Same average. Very different outcome. The gap has a name: volatility drag.
This post shows what volatility drag is, how to see it with a calculator, and why a bumpy 10% still beats nothing but loses to a smooth 10%.
Volatility is how much a price jumps around. A calm investment moves a little each year. A wild one swings up and down by a lot.
Volatility drag is the money you lose because of those swings. It is the gap between the average return you were told and the growth your balance actually got.
The cause is simple. Losses hurt more than gains help. If you lose 50%, you need a gain of 100% just to get back to zero. The bigger the swings, the more you pay for them.
Here are three made-up investments. This is NetWort arithmetic with invented returns, not real funds. Each one has an average return of exactly 10% a year over four years.
| Year 1 | Year 2 | Year 3 | Year 4 | Average | |
|---|---|---|---|---|---|
| A: smooth | +10% | +10% | +10% | +10% | 10% |
| B: bumpy | +40% | -20% | +40% | -20% | 10% |
| C: very bumpy | +60% | -40% | +60% | -40% | 10% |
The average is the plain "add up and divide" average, also called the arithmetic average. All three are the same: 10%.
Now see what happens to Rp100 juta in each.
| Balance after 4 years | Growth per year (CAGR) | |
|---|---|---|
| A: smooth | Rp146.4 juta | 10.0% |
| B: bumpy | Rp125.4 juta | 5.8% |
| C: very bumpy | Rp92.2 juta | -2.0% |
CAGR is the steady yearly growth rate that matches your real ending balance. If the term is new, our guide on how to calculate CAGR takes about a minute to read.
Investment A grew 10% a year, just as the average promised. Investment B grew only 5.8% a year. Investment C lost money, even though its average return was a healthy 10%.
You do not need special software. For investment B, multiply the growth factors for each year. A +40% year is a factor of 1.4. A -20% year is a factor of 0.8.
1.4 × 0.8 × 1.4 × 0.8 = 1.2544
So Rp100 juta becomes Rp125.44 juta. Compare that with the Rp146.41 juta you would get from 1.1 × 1.1 × 1.1 × 1.1.
The difference, about Rp21 juta, is the drag. Nobody charged you a fee. The swings themselves took it.
Now the other half of the title. Investment B ended with more than you started with. Rp125.4 juta beats Rp100 juta. So bumpy is not the same as bad.
Volatility drag does not say "avoid risk". It says "do not trust the average return alone". A bumpy investment can still grow your money. It just grows it less than the headline number suggests.
Think of it as a tax on turbulence. A small tax on mild swings. A big tax on wild ones.
There is a rough shortcut for the size of the drag. Take the standard deviation of the yearly returns. That is a measure of how far returns typically stray from their average. Square it, then halve it.
The shortcut says B grows about 10 − 4.5 = 5.5% a year, and C about 10 − 12.5 = -2.5%. The real answers were 5.8% and -2.0%. Close enough to guide your thinking, though it is only an approximation.
The key idea: drag grows with the square of the swings. Double the swings and the drag is about four times bigger.
Real stocks and crypto do not follow tidy patterns like +40% then -20%. But the same effect is at work. Two assets with the same average yearly return will leave you with different money if one is much more volatile.
This is also why a headline like "averaged 10% a year" can mislead. Ask for the compounded figure. Our post on the arithmetic mean versus the geometric mean shows the same gap with real Bitcoin prices.
Drag is also one reason people spread money across different assets. A mix of holdings that do not move together can swing less than any single one. A related effect, where regular rebalancing can add back some growth, is covered in our guide to the rebalancing bonus.
To see how much different markets swing right now, the NetWort market overview shows volatility readings across Indonesian stocks, US stocks and crypto.
Open the NetWort Dashboard and look at your Portfolio Health score. See which holdings swing the most. Then ask whether the extra bumpiness is paying you enough to be worth the drag.