# MEV Shapes DeFi Trades Through Arbitrage, Sandwich Attacks and Flashbots Tools By Simon Yoon Canonical URL: https://www.tokenpost.com/news/technology/32418 Published: 2026-10-15T09:59:21.000Z Updated: 2026-10-15T09:59:21.000Z Section: Technology > Maximal extractable value comes from influencing transaction inclusion and ordering. Strategies can narrow price gaps or worsen a swap, while Flashbots Protect, MEV-Share and MEV-Boost serve different roles. An ordinary decentralized exchange swap can become a contest over block space: the same trade may tighten market prices or leave a user with a worse fill depending on how transactions are arranged. Maximal extractable value (MEV) refers to value participants capture by influencing which transactions a block includes or excludes and the order in which included transactions run. It is not a token; it is an economic result of block production. ## How transaction order creates value Ethereum moved to proof-of-stake with The Merge on Sept. 15, 2022. Validators propose blocks, searchers look for opportunities to earn MEV, builders assemble transactions and choose their order, and relays connect builders with validators. The roles show how opportunities can arise both when a block’s contents are selected and when its transactions are arranged. Order matters because one transaction can change the conditions another encounters. A large decentralized exchange trade, for example, can shift a pool’s price. A searcher who can place a trade before or after it may try to profit from that change. MEV therefore covers several strategies with different effects on traders and markets. ## Strategies can help markets or hurt a swap In arbitrage, a searcher buys an asset where it costs less and sells it where it costs more. That activity can narrow price differences between markets. Searchers compete for the opportunity, and transaction costs affect whether a trade is profitable. Decentralized lending protocols also create liquidation opportunities. Searchers compete to liquidate loans that meet a protocol’s rules, and the first successful liquidator may earn a fee. Competition can help liquidations happen promptly, but it can also increase transaction costs. A sandwich attack targets a swap that is visible while waiting in a public transaction pool, often called a mempool. A searcher buys the asset before the user’s swap, then sells after it. The first trade can move the pool price against the user, and the swap can move it further before the searcher sells. The user may receive fewer tokens or get a worse execution as a result. A poor swap result by itself does not show that a sandwich attack happened. The user’s own trade can move the pool price, while limited liquidity and market movements can also affect the final result. Price impact means the price change in a pool caused by a trade; slippage is the gap between the expected and actual swap price. A slippage limit determines how far the result can worsen before a transaction fails. A high limit may let a trade complete at a worse price, while a low limit may cause it to revert. Before confirming a swap, users can review its minimum output, displayed price impact and available liquidity. Private transaction routes can reduce the chance that bots see a pending swap in the public mempool, but they do not eliminate every form of MEV risk. Users still depend on the builders handling a private transaction to keep it private and avoid trading ahead of it. Aptos has also taken a protocol-level approach with an [optional encrypted mempool]() that hides transaction details until blocks reach finality. ## Flashbots tools work at different stages Flashbots Protect privately submits transactions to reduce their exposure in the public mempool. Private submission is not a guarantee: users rely on the builders receiving their transactions to keep them private and not trade ahead of them. MEV-Share has a different purpose. It lets users selectively share transaction information with searchers pursuing backrun opportunities, with some qualifying MEV potentially returned to users. Its default share is 90% of eligible MEV created by a transaction. That percentage applies to the MEV, not the swap’s value, and it does not promise a return on every transaction. MEV-Boost operates during block construction. Validators can use it to access a market of builders, making it distinct from a service that routes an individual user’s transaction. The tools address different stages: Protect changes how a transaction is submitted, MEV-Share lets users share selected information, and MEV-Boost connects validators with block builders. That distinction helps explain why one tool cannot be assumed to address every strategy associated with transaction inclusion and ordering. ## Links in this article - [optional encrypted mempool](https://www.tokenpost.com/news/technology/30324)