A leveraged ETF is not a product that "doubles your return" — it chases twice the daily move. So when the underlying index swings up and down and eventually returns to where it started, the leveraged ETF ends up below par. If the index starts at 100, rises 10% one day, then falls 10% the next to close at 99, a 2x product drops to 96. The index lost 1%; the product lost 4%. That gap is "negative compounding," commonly called volatility decay.
Toss Feed describes these products as asking whether you have "the heart of a beast or a moth to a flame" (Toss Feed). Get the direction right over a short stretch and they are powerful; let the direction whipsaw over time and the design itself works against the holder.
Decay comes from the "twice the daily move" design
A leveraged ETF resets its exposure back to 2x at the close of every trading day (rebalancing). It multiplies today's percentage move by two, not yesterday's price level. Over a single day it is exactly 2x, but over two or more days each day's return compounds, drifting away from a simple "2x of the index return."
One Korean explainer frames this as "positive and negative compounding" (Brunch). In a steadily rising market, compounding works in your favor and you can even beat 2x; in a choppy, sideways market, it stacks against you and magnifies losses. The same product behaves in opposite ways depending on the shape of the market.
Why does principal shrink when the index is flat?
The key is the asymmetry of recovery: a bigger gain is needed to undo a loss. If 100 falls 10% to 90, it needs an 11.1% gain to get back to 100. Leverage doubles that asymmetry. The table below calculates, from a starting value of 100, how far a 2x product drifts when the index "rises one day and falls the same amount the next," nearly returning to par.
| Daily swing (up then down) | Index after 2 days | 2x leverage after 2 days | Naive 2x expectation | Volatility loss |
|---|---|---|---|---|
| ±5% | 99.75 (-0.25%) | 99.00 (-1.00%) | -0.50% | -0.50pp |
| ±10% | 99.00 (-1.00%) | 96.00 (-4.00%) | -2.00% | -2.00pp |
| ±20% | 96.00 (-4.00%) | 84.00 (-16.00%) | -8.00% | -8.00pp |
| ±30% | 91.00 (-9.00%) | 64.00 (-36.00%) | -18.00% | -18.00pp |
The larger the volatility, the more the loss swells — close to the square of the swing. At ±10% the index is down 1% while the 2x product is down 4%; at ±30% the index is down 9% while the product is down 36%. Decay speed is known to be determined exponentially by holding period, asset volatility, and the square of the leverage ratio.
A leveraged ETF promises "twice the daily move," not "twice the return." Once days pile up, that promise resolves into wildly different outcomes depending on the shape of the path the index traced.
Inverse and 2x-inverse products dig the same trap
Inverse products that bet on a decline, and their 2x version (gopbeoseu, -2x), rebalance daily the same way, so they cannot escape negative compounding. Say the index moves +10% then -10% and ends at 99. Since the index fell 1%, a -2x product betting on a drop looks like it should profit — but it actually goes 100 to 80 to 96, a 4% loss. You got the direction (a falling index) right, yet the choppiness itself ate the asset.
On top of this sits the risk of the market price diverging from NAV (net asset value). Where index and product prices pull apart is covered separately in the difference between ETF tracking error and price disparity.
In a trending market it works the other way — so direction is everything
To keep this balanced: in a market that rises steadily in one direction, positive compounding kicks in and leverage can exceed a plain 2x. The problem is that no one knows in advance when the market will trend and when it will chop. That makes these products short-term tools tied to a narrowly specified direction and window, not buy-and-forget long-term holdings. The Korea Center for Investor Education also notes that negative compounding and relatively high trading costs can make them unsuitable for long-term investing (KCIE).
What to watch
- Holding period — hold past one day and you have already begun to diverge from a simple 2x. Multi-day or multi-week holds depend heavily on the path.
- Market regime — a clearly trending market versus a choppy, sideways one. The more sideways, the larger the volatility loss.
- Underlying volatility — the higher a gauge like VKOSPI, the faster the erosion over the same window.
- Disparity and fees — how far the market price sits above NAV, and how much higher the annual fee is versus a plain index ETF.
- Square of the multiplier — a 3x product does not lose 1.5x more than a 2x; the loss scales closer to the square, steepening fast.