Impermanent Loss: How It Works and When It Applies

Impermanent loss is a change in the value of assets deposited into an automated market maker (AMM) liquidity pool compared with simply holding those assets outside the pool. It is not a fee charged by the platform, and it is not a loss that appears in a transaction history. It is a mathematical consequence of how AMMs keep the two sides of a trading pair in balance.

When a trader swaps token A for token B in a pool, the pool adjusts the ratio of the two tokens. The constant product formula (x * y = k) means that after the trade, the pool holds more of the token that was bought and less of the token that was sold. The price of each token in the pool moves to reflect the new ratio. If the external market price of one token rises, arbitrageurs will buy the underpriced token from the pool until the pool price matches the market. That process leaves the pool holding a different mix of tokens than when you deposited.

Your share of the pool is a claim on that new mix. If the price of one token has moved significantly, the total value of your share can be less than the value of the original deposit, even though the pool itself has grown in value from trading fees. The shortfall is impermanent loss.

The Mechanics of Rebalancing

Consider a pool with two tokens, A and B. You deposit 1 A and 100 B, with an initial price of 1 A = 100 B. The pool’s constant product is 1 * 100 = 100. If the market price of A rises to 200 B, arbitrageurs will buy A from the pool until the pool price matches. The pool’s new ratio will be approximately 0.707 A and 141.4 B. Your share is now 0.707 A and 141.4 B. At the new market price, that is worth 0.707 * 200 + 141.4 = 282.8 B, while holding the original deposit would be worth 1 * 200 + 100 = 300 B. The difference, about 17.2 B, is the impermanent loss.

The loss is called “impermanent” because if the price returns to the original ratio, the pool rebalances back, and the loss disappears. However, if you withdraw while the price is away from the original ratio, the loss becomes realized and permanent. The name is a description of the state, not a guarantee that the loss will reverse.

When It Applies and When It Does Not

Impermanent loss applies to any AMM liquidity pool where you deposit two assets and receive a share of the pool. It does not apply to single-sided staking, lending, or holding assets in a wallet. The table below summarizes common scenarios.

The Misdiagnosis: Why People Blame the Wrong Thing

A common misunderstanding is that impermanent loss is caused by the pool “taking” your money, or that it is a form of fee charged by the platform. In reality, the pool is simply following the constant product formula. The loss arises because you are effectively providing both sides of a trade, and when the price moves, you are on the losing side of the arbitrage.

Another misdiagnosis is that impermanent loss is a bug or a flaw that can be avoided by choosing a “better” pool. Every AMM with a constant product has the same mathematical property. Some pools use different formulas (e.g., stableswap for stablecoins), which reduce the loss for assets that are expected to stay close in price, but they still have the same underlying principle.

The mistake is natural because the loss is invisible. It does not show up as a negative balance or a fee line. It only appears when you compare your current position to what you would have had if you had not deposited. That comparison is easy to skip, especially when the pool is generating fees that mask the loss.

How It Nets Against Fees

Liquidity providers earn trading fees for every swap that occurs in the pool. These fees are added to the pool and increase the value of your share. The net result of providing liquidity is the sum of the fees earned minus any impermanent loss.

If the price stays relatively stable, fees can outweigh the loss, making liquidity provision profitable. If the price moves sharply, the loss can exceed the fees, resulting in a net loss compared to holding. The longer you stay in the pool, the more fees you accumulate, but the loss also compounds if the price continues to move away.

There is no fixed rule for when fees cover the loss. It depends on the volatility of the pair, the trading volume, and the fee tier. A high-volume pool with low volatility can generate enough fees to offset small losses, while a low-volume pool with high volatility may not.

What People Get Wrong About Impermanent Loss

The most persistent error is thinking that impermanent loss is only a paper loss that always reverses. It reverses only if the price returns to the original ratio. If you withdraw after a price move, the loss is permanent. Many providers have experienced a sharp price move, seen the loss on a dashboard, and assumed it would disappear, only to find it realized when they exited.

Another error is believing that impermanent loss is a small, negligible factor. In a highly volatile pair, the loss can be substantial, even exceeding the fees earned over a long period. A 50% price move can cause a loss of about 5.7% of the deposited value. A 90% move can cause a loss of about 23%. These are not trivial.

A third error is that impermanent loss is the same as a “rug pull” or a scam. It is not. It is a transparent, mathematical outcome. The pool does not hide it, but it is also not prominently displayed in every interface. The responsibility is on the provider to understand the mechanics.

Calculating Impermanent Loss

You can calculate the approximate impermanent loss for a given price change using the formula:

IL = 2 * sqrt(price_ratio) / (1 + price_ratio) - 1

Where price_ratio is the new price of the moved asset divided by the original price. For example, if the price doubles (ratio = 2), the IL is about -5.7%. If the price halves (ratio = 0.5), the IL is also about -5.7% because the formula is symmetric.

To see the effect on your position, you can use a spreadsheet or an online calculator. The output is a percentage that represents the loss relative to holding. A negative percentage indicates a loss.

Practical Implications

Before depositing into a liquidity pool, consider the following:

• Volatility: Pairs with high volatility are more likely to experience impermanent loss. Stablecoin pairs have low volatility and therefore low loss.
• Fees: Higher fee tiers can compensate for loss, but they also reduce trading volume. There is a trade-off.
• Time horizon: The longer you stay, the more fees you earn, but the loss can also grow if the price trends. There is no guarantee that fees will eventually cover the loss.
• Exit strategy: If you need to withdraw at a specific time, you may be forced to realize a loss. Plan for that possibility.

Impermanent loss is not a reason to avoid liquidity provision altogether, but it is a reason to understand the mechanism before committing funds. It is a risk that is often omitted from marketing materials, which focus on fee yields. The reality is that providing liquidity is not a passive income strategy; it is an active position with its own risk profile.

Why impermanent loss happens in AMM pools

Impermanent loss is a fundamental property of AMM liquidity pools. It occurs because the pool rebalances against you when the price moves, and it becomes permanent when you withdraw. It is not a fee, not a scam, and not something that always reverses. It nets against the fees you earn, and the outcome depends on the pair’s volatility and the pool’s volume. Understanding this mechanism is essential for anyone considering providing liquidity.