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Impermanent loss is the value difference between an AMM liquidity position and a stated hold benchmark after relative asset prices change.

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Impermanent loss compares an AMM liquidity position with a specific hold benchmark after the assets’ relative price changes.

An AMM automatically changes its inventory as traders move along the pricing rule. The LP therefore ends with different asset quantities than someone who held the starting quantities outside the pool. Impermanent loss isolates that benchmark difference; it is not total profit and loss.

Rebalancing shortfall against buy-and-hold is a useful analogy. The measure is conditional on a benchmark, interval, valuation price, and AMM model. “Impermanent” does not mean unrealized, guaranteed to reverse, or harmless after withdrawal.

For an initially balanced, two-asset, full-range constant-product position with no fees, let:

r = ending external price / initial external price
impermanentLossFraction = 2 × sqrt(r) / (1 + r) - 1

r and the result are unitless. At r = 1, the difference is zero. For any other positive r, this expression is negative relative to holding the original quantities. The symmetry between r and 1/r depends on this selected model.

Do not apply the formula unchanged to concentrated ranges, unequal weights, multi-asset pools, stable-swap curves, dynamic fees, rebalancing strategies, or positions entered off the reference ratio.

Position balance-sheet and benchmark ledger

Section titled “Position balance-sheet and benchmark ledger”

The metric is invalid when the two columns use different times, price sources, units, or fee treatments.

  1. An LP contributes the starting asset mix and receives a position claim.
  2. Relative external prices change.
  3. Traders and arbitrageurs alter pool reserves toward executable market prices.
  4. The LP claim now represents a different inventory mix.
  5. Value both the LP position and original hold quantities at the same prices.
  6. Report their difference separately from fees, incentives, and costs.

Capital flow is the inventory traded into and out of the pool. Claim flow is the LP position. Return flow includes trader-paid fees and explicit incentives. Risk flow reaches the LP through inventory rebalancing, adverse selection, token loss, ranges, contract failure, and strategy costs.

Impermanent loss is a benchmark difference, not an invoice from one named payer. Counterparties and arbitrageurs trade against the changing inventory; their economics, combined with external price movement, produce the LP’s reserve mix. The LP bears the difference unless fees or other income offset it. A positive total LP return can coexist with negative impermanent loss, and vice versa.

The comparison assumes identical starting quantities, valuation time, price source, numeraire, fee treatment, and cost treatment for the LP position and the hold benchmark. The closed-form equation additionally assumes a balanced, full-range, two-asset constant-product pool with positive prices and no fees. Using mismatched inputs, a different AMM curve, concentrated liquidity, or an unreconstructed position makes the result inapplicable. Separately, token, oracle, pool-contract, or strategy failure can reduce the LP’s actual value; those losses are not impermanent loss and should be reported on their own.

Require the benchmark quantities, entry state, exit state, valuation currency, price source, time interval, AMM model, fee treatment, ranges, and rounding. Test r = 1, reciprocal price changes, very small and large positive ratios, zero/invalid prices, and comparisons against independently reconstructed reserves. Keep impermanent loss, LVR, fees, incentives, and total P&L separate.

Uniswap v2’s returns documentation derives this formula for its simplified model. The research on loss-versus-rebalancing studies a related but distinct adverse-selection cost. Neither source justifies applying the formula to every AMM or claiming fees will offset the loss. The living Uniswap documentation was reviewed 2026-08-10; the research paper is a dated analytical artifact, not a current protocol-behavior source.

  • “Impermanent means it is not real.” Withdrawal can realize the position outcome, and reversal is not guaranteed.
  • “Impermanent loss equals total LP loss.” It excludes or separately treats fees, incentives, gas, financing, and token-level gains or losses.
  • “One formula works for every pool.” Curve, weights, ranges, entry state, fees, and management rules change the model.

Return to the liquidity-provider page to place this benchmark inside total LP economics.

Machine-readable model

Key equations

Canonical expressions come from the structured concept record. KaTeX renders the notation, while the plain-text expression and variable table keep its meaning and units inspectable without JavaScript. Read the narrative above for the model's domain, assumptions, and rounding rules.

  1. Equation 1

    Plain-text equation: impermanentLossFraction = 2 * sqrt(priceRatio) / (1 + priceRatio) - 1

Assurance contract

Security properties

These structured statements define desired behavior. Their stable IDs can bind tests, invariants, specifications, audit findings, or proof results without turning descriptive review advice into an assurance claim.

Desired · not evaluated: No test, audit, or proof result is implied until scoped evidence is linked to this property.

  1. Calculations state the benchmark quantities, valuation currency, interval, price source, fee treatment, and AMM model

  2. The selected formula is used only inside its stated domain and assumptions

  3. Position value, hold value, fees, incentives, gas, and realized withdrawals remain separately inspectable

  4. User interfaces do not describe a benchmark-relative metric as a guaranteed temporary loss

Knowledge check

Quiz

Answer in your own words, then open the model answer.

What problem does Impermanent loss exist to address?

Model answer

The metric isolates how rule-based inventory rebalancing changes a liquidity provider's outcome compared with keeping the benchmark asset quantities outside the pool.