On a DEX, your trade enters a public mempool where searchers can see it before execution. This creates Maximal Extractable Value (MEV) — profit extracted by reordering, front-running, or sandwiching your transaction. A sandwich attack buys ahead of you, lets your slippage push the price up, then sells immediately after.

CEXs internalize this flow through a private order book, so retail users rarely experience sandwiching — but the exchange itself may run proprietary trading desks with visibility into client orders.

Front-running: bot pays higher gas to land before your buy
Back-running: bot buys right after your large order moves price
JIT liquidity: LP adds liquidity in the same block, captures fees, then withdraws

Venue	MEV exposure	Mitigation
Public DEX	High	Private RPC, slippage caps
CEX	Low (retail)	None needed
Dark pool DEX	Minimal	Encrypted mempool