A massive DeFi transaction on March 12 resulted in a staggering loss of nearly $50 million for a single cryptocurrency user. The costly blunder reportedly stemmed from the user overlooking a slippage warning while approving a transaction via a mobile device. As recorded on the Ethereum blockchain, approximately $50.43 million worth of aEthUSDT tokens were swapped for just 327.24 aEthAAVE using the CoW Protocol. The final market value of the received tokens, however, totaled merely $36,000—shedding light on the immense costliness of a seemingly routine swap.
Identity Claims and Trading History
Blockchain analytics platform Lookonchain suggested that the major loss might be tied to Garrett Jin, a well-known trader in crypto circles. Jin is particularly recognized for his high-volume Bitcoin trades. His name previously surfaced in connection with a lucrative Bitcoin short position taken in 2025, just before then-U.S. President Donald Trump announced additional tariffs against China—a move that fueled allegations of market manipulation. Jin countered the speculation at the time, emphasizing that all capital belonged to clients and denying any access to insider information. So far, Jin has not issued any public response regarding the recent incident.
MEV Bots and Other Winners in the Transaction
The lost fortune did not solely benefit DeFi protocols. Several actors within the Ethereum ecosystem reaped substantial profits as a result of the transaction. According to analyst Emmet Gallic of Arkham Intelligence, a maximal extractable value (MEV) bot exploited arbitrage opportunities between Uniswap and SushiSwap pools during the swap, earning significant revenue. This bot reportedly paid 16,927 ETH—about $34.8 million—to block builder Titan Builder. Titan Builder, in turn, routed around $1.2 million to Lido validators and kept the bulk as profit, emerging as the top earner among crypto platforms that day. The MEV bot operator also reportedly secured profits nearing $10 million from the single transaction.
Aave and CoW Swap: User Was Warned
In the wake of the event, both Aave and CoW Swap emphasized that a clear slippage warning had been displayed and that the user had to manually confirm the approval for the transaction to proceed. Aave founder Stani Kulechov detailed that the user had actively dismissed the warning by overriding the slippage protection on mobile. Kulechov offered a technical assessment:
“The transaction could not move forward without the user explicitly acknowledging the risk by ticking the confirmation box.”
CoW Protocol likewise asserted that there was no software vulnerability or evidence of malicious action, adding that all conditions had been met according to the signed order:
“There was no flaw in the protocol, nor any sign of bad intent. The transaction was completed exactly as signed and submitted.”
Both protocols announced plans to refund transaction fees to the affected user, with the total amounting to around $600,000. CoW Protocol also stated that any additional fees collected by its platform would be returned to the user as part of restitution.
Rethinking Security in the DeFi User Experience
The debacle has reignited debate over user risks and safeguards in large-scale decentralized finance transactions. Suhail Kakar, CTO at Polymarket, argued that the losses were not due to smart contract failures but rather shortcomings in user interface protection. Kakar emphasized the need for wallets and interfaces to better highlight potential dollar-value losses and called for stricter controls, especially for high-value transactions. Both Aave and CoW indicated they would implement stronger protective measures going forward. CoW Protocol commented on balancing user autonomy with safety improvements in its interface:
“Blocking user transactions can sometimes lead to unwanted outcomes. However, incidents like this show DeFi interfaces still do not sufficiently protect users. We are reassessing how to balance robust protections with user freedom in our design.”
