A cryptocurrency trader lost nearly $50 million during a token swap executed through the decentralized finance protocol Aave after a combination of extreme price impact and a Maximal Extractable Value (MEV) attack drastically altered the outcome of the transaction.
Blockchain data shows the user attempted to convert approximately $50.4 million worth of tether into the AAVE token. Instead of receiving a large position in the asset, the wallet obtained only a few hundred tokens valued at roughly $36,000.
The incident has sparked debate across the decentralized finance ecosystem about user protections, liquidity risks, and the growing influence of automated trading bots.
$50 million trade results in minimal return
The wallet involved in the transaction received the funds shortly after withdrawing assets from Binance. The user attempted to swap the entire amount of aEthUSDT into aEthAAVE through the Aave mobile interface.
The swap route passed through CoW Protocol and eventually executed on the decentralized exchange SushiSwap.
According to blockchain records on Etherscan, the trader received only 324 AAVE tokens, worth around $36,000 at the time of execution.
The result placed the effective price of the tokens at roughly $154,000 per AAVE. Market prices for the asset hovered near $114 during the transaction.
Warnings appeared before the trade
Developers behind Aave stated that the application warned the user about extreme price impact before the swap was executed.
Aave founder Stani Kulechov addressed the event publicly and described how the interface responded to the unusually large order.
“Earlier today, a user attempted to buy AAVE using $50M USDT through the Aave interface. Given the unusually large size of the single order, the interface warned the user about extraordinary slippage and required confirmation via a checkbox. The user confirmed the warning on their mobile device and proceeded with the swap.”
Slippage refers to the difference between the price expected during a trade and the price received after the transaction executes. Automated market makers such as SushiSwap adjust token prices depending on liquidity depth and order size.
In this case, the quoted rate already reflected extreme price impact before the swap occurred.
Engineer Martin Grabina later clarified that the main problem was not the slippage setting itself.
“In this case, the user sent a market order with the suggested 1.21% slippage. But the core issue wasn’t slippage, it was just the accepted quote with 99% price impact,” Grabina wrote.
MEV bot captured millions from the trade
Blockchain data also revealed activity from a trading bot that targeted the transaction while it remained pending in the Ethereum mempool.
The bot carried out what is known as a sandwich attack. This strategy allows automated traders to place transactions before and after a large order to capture price movement created by the original trade.
The MEV searcher used a flash loan to borrow about $29 million in wrapped ether and purchase AAVE tokens before the whale transaction executed. The bot then sold the tokens at inflated prices after the trade.
The maneuver generated an estimated profit of about $9.9 million.
To secure priority inclusion in the block, the searcher reportedly paid 16,927 ETH to Titan Builder. Data later indicated that the builder transferred 568 ETH to the validator responsible for proposing the block.
Investigators reviewing the transaction said the routing path through the aToken wrapper significantly amplified the price distortion.
Protocols respond after the incident
Both Aave and CoW DAO addressed the situation shortly after it circulated across crypto social media.
CoW DAO said the swap executed exactly as the signed order specified and confirmed that the interface displayed warnings about the potential loss.
“Despite clear warnings that showed the user they would lose nearly all of the value of their transaction, and despite needing to explicitly opt into the trade after seeing the warning, the user chose to proceed with their swap.”
Statement from CoW Protocol:
— CoW DAO (@CoWSwap) March 13, 2026
Earlier today, a trader attempted to swap 50M aEthUSDT for aEthAAVE through Aave's swap interface, which is powered by CoW Protocol. Despite clear warnings that showed the user they would lose nearly all of the value of their transaction, and despite… https://t.co/Pav4udXUkX
The organization also said no decentralized exchange or liquidity pool could have filled a transaction of that size at a reasonable price.
Developers acknowledged that the event highlights user-experience limitations within decentralized finance platforms.
“Trades like this show that DeFi UX still isn’t where it needs to be to protect all users,” the organization said.
Meanwhile, Kulechov stated that Aave plans to return about $600,000 in protocol fees generated during the transaction.
“We sympathize with the user and will try to make contact with the user and return $600K in fees collected from the transaction.”
The wallet owner has not publicly commented on the incident.
A costly reminder for DeFi traders
Large market orders on decentralized exchanges rely heavily on liquidity pools. Thin liquidity can lead to severe price impact when traders attempt to swap large amounts in a single transaction.
The episode demonstrates how open blockchain infrastructure allows complex financial activity but also exposes users to significant risk.
Developers across the ecosystem have discussed stronger safeguards after the incident. Proposed ideas include stricter trade limits and additional confirmation steps for extremely large orders.
However, decentralized finance platforms continue to operate under permissionless rules. Protocols provide tools and warnings, but final decisions remain in the hands of users.
Gunel Ismayilova
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