Guide · Risk Management
Front-Running: When Someone Trades Ahead of You on Purpose
Front-running means acting on advance knowledge of a trade that hasn't happened yet — and in crypto, it doesn't always take a person on the inside to pull off.
Front-running is trading ahead of a known, pending order using information about that order that isn't available to the rest of the market — buying an asset right before a large buy order is about to push its price up, for instance, then selling into the demand that order creates. In traditional finance, it's typically a broker or exchange employee misusing knowledge of a client's pending order — a serious regulatory violation.
On public blockchains, a structurally different version of the same idea doesn't require any inside access at all: every pending transaction sits visibly in a public queue (the "mempool") before it's confirmed, and anyone running the right kind of bot can see a large pending trade, submit their own transaction with a higher fee to get processed first, and profit from the price impact the original trade was about to cause. This category is broadly known as MEV (maximal extractable value).
The mechanics differ from traditional front-running (no insider, no broker, no violation of any duty in the legal sense in most jurisdictions), but the economic effect on the person who submitted the original trade is the same: a worse execution price than they would have gotten otherwise, extracted by someone who saw their order coming.
It's a genuinely difficult thing to protect against as an individual trader, but understanding that it exists — and that unusually large, unhurried orders on public blockchains are the ones most exposed to it — is worth factoring in before sizing a real trade on-chain, and testing order sizing on Trade2Spike is a reasonable place to build that intuition first.