Encyclopedia DeFi · Entry 57
DeFi arbitrage: why prices converge and differences can remain
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Price link | Arbitrage can bring pool prices closer to external markets. | [2] |
| Ordering | Competition for transaction order affects opportunities. | [1] |
| Atomic borrowing | A pure flash loan must settle within its transaction. | [3] |
A spread is the start of a calculation
Suppose a tiny purchase of A costs 100 B on one venue and a tiny sale pays 102 B on another. The two-unit difference is an indicative spread. Buying a substantial quantity can raise the purchase rate while selling it can lower the sale rate.
A complete calculation uses executable amounts, both venues’ fees, gas and any borrowing cost. It also accounts for token identity: similarly named bridged or wrapped assets are not automatically interchangeable claims.
One transaction can combine several legs
On a compatible chain, contract calls can attempt a purchase, sale and repayment within one transaction. If a required condition fails and the transaction reverts, its state changes are rolled back. Gas already used by an included attempt still has a cost.
A pure flash loan supplies temporary capital under that atomic condition. It does not guarantee that a profitable sequence exists. Moving funds across independent chains or a centralized venue can introduce timing and custody steps outside the atomic transaction.
Why a gap may disappear before execution
Other searchers can spot the same opportunity and compete for inclusion or a favorable order. The price difference visible at a previous block may disappear before a submitted transaction executes.
Arbitrage supplies a mechanism connecting prices rather than a promise that prices are always equal. Fees, inventory limits and execution constraints can maintain differences. When citing a spread, record its venues, assets and observation time.
Direct answers
Questions people ask
Is a visible price difference free money?
No. The useful comparison is the completed trade after all legs, costs and price impact. Competitors and changing state can remove the opportunity before execution.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
Arbitrage combines purchases and sales across markets to exploit a price difference. In DeFi it can move AMM inventory toward prices elsewhere. A displayed spread is not a guaranteed profit: trade impact, fees, execution order and the ability to complete every leg all affect the result.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimPrice link: Arbitrage can bring pool prices closer to external markets.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimOrdering: Competition for transaction order affects opportunities.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimAtomic borrowing: A pure flash loan must settle within its transaction.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimRevision history
- — First publication after primary-source research and independent automated verification.
- — Before first publication, independent review checked and revised: sections, sources. Read MEV arbitrage/order competition, v2 reserve pricing and Aave atomic flash-loan execution. Spread is correctly indicative until all costs and executable quantities are included. Added EIP-140 support for state rollback and consumed-gas qualification. Cross-chain/custodial legs are excluded from a single-chain atomic guarantee.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- Maximal extractable valueethereum.org contributors
Transaction ordering, arbitrage, liquidation and sandwich mechanisms.
Locator: MEV extraction; Examples of MEV · Retrieved: 2026-10-02Open source - Uniswap v2 pricingUniswap
Reserve-dependent quotes, trade bounds and external price observations.
Locator: Pricing Trades; Exact Input; Exact Output · Version / scope: Uniswap v2 · Retrieved: 2026-10-02Open source - Aave V3 flash loansAave
Atomic repayment, receiver callbacks and distinct debt-opening options.
Locator: Overview; Execution Flow; Flash loan fee · Version / scope: Aave V3 · Retrieved: 2026-10-02Open source - EIP-140: REVERT instructionEthereum Improvement Proposals
Reverting rolls back state but does not refund work already executed; unused gas is not all consumed.
Locator: Specification; Test Cases · Version / scope: EIP-140 final · Retrieved: 2026-10-02Open source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees of Satoshi editorial project. “DeFi arbitrage: why prices converge and differences can remain.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/defi-arbitrage/