What is MEV (maximal extractable value)?
MEV is the value that can be taken by reordering, inserting or leaving out transactions in a block. Sandwiches, arbitrage and liquidations, and how to protect your swaps.
Updated Nov 8, 2026
In short
Maximal extractable value (MEV) is the profit someone can make by choosing which transactions go into a block and in what order. Some of it is useful, like arbitrage that keeps prices in line. Some of it costs you, like a sandwich: a bot buys just before your swap and sells just after, so you fill at the worst price your slippage allowed. Tight slippage, limit orders and private transaction routes reduce what can be taken.
How it works
Transactions usually wait in a public queue before they're put in a block. Whoever builds the block decides their order. Bots watch the queue and pay to have their own transactions placed just where they profit.
Common kinds
- Arbitrage: buying where a token is cheap and selling where it's dear, often between DEXs. It keeps prices in line and doesn't take from you directly.
- Liquidations: bots compete to liquidate loans that fall below their threshold and collect the bonus. This is how lending protocols stay solvent, and why a loan close to the line rarely gets a second chance.
- Sandwiches: a bot sees your swap, buys before it to push the price up, lets your swap fill at that worse price, then sells. Your loss is up to your slippage tolerance.
How to protect yourself
- Keep slippage tight, especially on large swaps and thin pools. See slippage.
- Use limit orders when you don't need to fill right now: they fill at your price or not at all.
- Use routes that don't broadcast your swap publicly before it's included, where your wallet or app offers them.
- Keep loans far from liquidation, so liquidation bots never have a reason to look at you.
In Burokku
Burokku's limit orders fill onchain at your price or better. Swap & Bridge shows what you'll receive before you sign, and liquidation alerts warn you long before a loan is something bots compete over.
Questions
- Does MEV happen on every chain?
- In some form wherever transactions wait in public before they're included. How much depends on the chain, how blocks are built, and whether your transaction is visible before it lands.
- Can I see if I was sandwiched?
- Usually, by looking at the transactions just before and after yours in the same block: a buy of the same token right before and a sell right after is the pattern.