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MEV stands for Maximal Extractable Value. It refers to value that can be captured when transactions are ordered, included, or excluded from blocks in a particular way. In plain language, MEV can happen when validators, searchers, or specialized bots identify an opportunity to profit from transaction ordering. For example, someone may try to place a transaction before yours to benefit from the price movement your trade creates. This is commonly called front-running. A related risk is a sandwich attack, where a bot or searcher attempts to trade before and after your swap. This can cause your swap to execute at a less efficient price than expected.
MEV and transaction-ordering risks are not unique to Orca. They can affect onchain transactions on Solana and many other blockchains.

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Why MEV can happen on Solana

Solana transactions are processed by validators. Validators and network infrastructure play a role in which transactions are included in a block and the order in which they are processed. Because transaction ordering happens at the network level, onchain Solana transactions may be exposed to MEV or similar ordering risks. This is a chain-level reality of interacting with Solana and many other blockchains. It is not unique to transactions initiated through the Orca interface or the Whirlpools smart contract.

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Where this risk lives

MEV risk mainly exists at the validator and transaction-routing level. Orca does not control Solana validators, determine the final ordering of transactions on Solana, or capture or profit from MEV on user swaps.
Orca cannot remove MEV or transaction-ordering risk. Your transaction may still be affected by network-level ordering, routing, or execution conditions.

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How MEV can affect your swap

MEV may affect a swap by causing your transaction to execute at a worse price than expected. The most common user-facing impact is worse execution, meaning you may receive fewer tokens than the quoted estimate. Before submitting a swap, review the quoted output, minimum received, price impact, route source, fees, and slippage setting.

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Ways to reduce MEV risk

You cannot remove MEV risk completely, but there are steps that may reduce it.
Slippage is the maximum price movement from the quoted amount that you are willing to accept for a trade.A tighter slippage setting gives less room for your trade to execute at a worse price. However, if your slippage is too tight, your transaction may fail.A looser slippage setting may make a transaction more likely to succeed, but it can also increase the risk of receiving a worse price.See Understanding Slippage for more details.
Large trades can create larger price movements and may be more visible to bots or other market participants.Splitting a large trade into smaller trades may reduce the size of each individual opportunity, but it can also expose you to changing prices across multiple transactions.This does not guarantee better execution and may increase fees, transaction costs, or execution complexity.
Some users may choose to broadcast transactions through third-party services such as Jito, which offers transaction-routing features designed to reduce certain MEV risks on Solana.Jito’s documentation describes features related to transaction landing, MEV protection, revert protection, and bundle-based transaction submission.These services are separate from Orca. Orca does not operate Jito, does not control Jito’s infrastructure, and does not guarantee that Jito or any other third-party routing service will prevent MEV, improve execution, or protect a transaction in all cases.Your choice of wallet, RPC provider, transaction broadcaster, or routing service may affect how your transaction is submitted to the Solana network.Learn more: Jito transaction-routing, bundle, and MEV-protection documentation

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Important limitations

MEV protection is not guaranteed. Jito-related infrastructure is widely used across Solana, but coverage and protection can vary. Even when a transaction is routed through a MEV-protection service, that service may not protect against every form of transaction-ordering risk. Orca does not guarantee the availability, quality, or effectiveness of any third-party MEV-protection service. Before submitting a transaction, review your trade details, expected output, price impact, route, and slippage settings.

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Key takeaways

  • MEV can occur when transaction ordering creates opportunities for validators, searchers, or bots.
  • MEV risk exists at the validator and transaction-routing level.
  • Orca does not control Solana validators or final transaction ordering.
  • MEV may cause worse execution, including receiving fewer tokens than expected.
  • Tighter slippage, smaller trade sizes, and protected transaction routing may reduce some MEV risk, but none of these remove the risk completely.
  • Third-party routing or MEV-protection services are separate from Orca and are not guaranteed to protect every transaction.