Front-Running

What is Front-Running?

Front-running is a type of market manipulation where an attacker (often a bot) identifies a pending transaction in the public mempool and quickly places their own transaction ahead of it. This allows the attacker to profit from the price movement caused by the victim's trade.

How does Front-Running work?

1. A user submits a large trade on a decentralized exchange (DEX).
2. The transaction enters the "mempool," where it is visible to all network participants.
3. An automated bot detects the transaction and calculates how much it will move the token's price.
4. The bot submits its own buy order with a higher gas fee to ensure it is processed first.
5. The victim's trade then executes, pushing the price even higher.
6. The bot immediately sells its tokens at the inflated price, capturing a guaranteed profit.

Why does Front-Running matter?

Front-running results in "slippage" for honest users, meaning they receive fewer tokens for their money than they should have. It is a major component of MEV (Maximal Extractable Value) and represents a significant hidden "tax" on DeFi participants.

Key features of Front-Running

• Exploits the transparency of the mempool
• Relies on "gas bidding" to manipulate transaction order
• Causes financial loss to the victim via price slippage
• Primarily executed by sophisticated automated bots
• Common in low-liquidity or high-volume trading pairs

Examples of Front-Running

A "sandwich attack" is the most common form of front-running. The attacker "sandwiches" the victim's trade between their own buy and sell orders, effectively siphoning off a small percentage of the trade's value.