DeFi Trader Loses $50.4M in Single Swap After MEV Sandwich Attack
A large trader executing a single swap suffered a $50.4 million loss when a mempool leak exposed the pending transaction to an MEV bot. With thin liquidity on the target pool and inadequate slippage protection, the bot executed a classic sandwich—front-running and back-running the trade—amplifying price impact and extracting the difference. Protocol-level failures prevented cancellation or mitigation, leaving the counterparty and liquidity providers to absorb the hit while the attacker realized the proceeds.
The event underscores how public mempools, aggressive MEV strategies, and weak user protections create systemic risk for sizable on-chain orders. It increases urgency for private transaction relays, batch auctions, improved default slippage settings, and greater use of off-chain OTC solutions for large trades. Exchanges, protocol teams, and auditors will likely face renewed pressure to harden settlement layers to prevent repeat meltdowns.