According to Cointelegraph, a cryptocurrency trader experienced a significant financial loss due to a sandwich attack while attempting to transfer $220,764 in stablecoins on March 12, 2025. The incident resulted in the trader losing nearly 98% of the transaction's value to a Maximum Extractable Value (MEV) bot. The bot managed to convert the USD Coin (USDC) into just $5,271 worth of Tether (USDT) within a mere eight seconds, effectively capturing over $215,500 from the transaction.
The attack took place on the decentralized exchange Uniswap v3's USDC-USDT liquidity pool, which holds approximately $19.8 million in locked value. The MEV bot executed the attack by front-running the transaction, temporarily removing all USDC liquidity from the pool before reinserting it post-transaction. Michael Nadeau, founder of The DeFi Report, explained that the attacker rewarded the Ethereum block builder "bob-the-builder.eth" with $200,000 from the swap, while personally gaining $8,000.
DeFi researcher "DeFiac" suggested that the same trader, possibly using multiple wallets, has been targeted by a total of six sandwich attacks. They noted that all funds involved originated from the borrowing and lending protocol Aave before being deposited on Uniswap. On March 12, two wallets, identified as "0xDDe…42a6D" and "0x999…1D215," were also victims of MEV bot attacks, losing $138,838 and $128,003, respectively, in transactions executed just minutes apart.
Speculation has arisen regarding the nature of these trades, with some suggesting they might be attempts at money laundering. The founder of crypto data dashboard DefiLlama, known as 0xngmi, proposed that illicit funds could be laundered by constructing a transaction vulnerable to MEV bots, allowing them to arbitrage it in a bundle with minimal losses.
Initially, Michael Nadeau criticized Uniswap for the incident, but later retracted his statements after Uniswap CEO Hayden Adams and others clarified that the transactions did not originate from Uniswap's front end, which includes MEV protection and default slippage settings. This clarification highlighted the measures Uniswap has implemented to combat sandwich attacks, emphasizing the importance of using protected interfaces for trading activities.
