What is MEV (Maximal Extractable Value)?

Maximal extractable value, or MEV, is the extra value that whoever orders transactions in a block, or bots watching the mempool, can extract by strategically arranging, inserting, or dropping transactions. Because pending transactions are public, sophisticated actors can profit at ordinary users’ expense, for example by front-running a visible trade.

This matters because MEV can quietly worsen the price you get on a DEX, particularly on large or high-slippage swaps that bots find attractive to exploit.

Example: a bot spots your large pending swap in the mempool, buys ahead of you to push the price up, lets your trade execute at the worse price, then sells, pocketing the difference in a sandwich attack.

Safety note: protect yourself by using sensible slippage limits, trading in liquid pools, splitting very large orders, and using MEV-protection features or private transaction routes where available. Be especially careful with high slippage tolerance on big trades, since it invites sandwich attacks. MEV is a structural risk, not a scam you can report, so trade defensively. Related terms include mempool, slippage, DEX, and front-running.