I recently saw a trader suffer huge losses due to something that could have been avoided. He tried to swap 220,000 USDC for USDT, but only received 5,200. So sad. Turns out, he was hit by a sandwich attack, and this happened because MEV is a real issue on the blockchain.

So what exactly is MEV? In short, MEV is Maximal Extractable Value — the maximum value that bots or validators can extract by manipulating the order of transactions in a block. Basically, they can see your pending transaction in the mempool, then insert their own transactions before and after yours. The result? You get caught in the middle and are forced to buy at a higher price or sell at a lower price.

This sandwich attack is the most common tactic. These bots basically spot opportunities and exploit them immediately. In the case of the trader earlier, the attacker made a profit of $8,000 and even tipped 200,000 to the block builder to help them out. Crazy, right?

What’s important to understand is that MEV is a feature of public blockchain design, not a bug. So this isn’t a system flaw, but how the system works. That’s why we need to know how to protect ourselves.

The key points are: first, always use a DEX frontend that has MEV protection built in. Second, set your slippage tolerance correctly — don’t set it too high. Third, avoid large swaps in small liquidity pools, as they become easy targets.

If you actively trade on DEXs, you should check your slippage settings right now. Gate has several DEX options with built-in MEV layer protections, worth checking out if you’re not familiar. Basically, awareness of MEV is the first step to protecting your portfolio.