TLDR
- On March 12, 2026, a cryptocurrency trader suffered a catastrophic loss of approximately $50 million during a token exchange on the Aave DeFi platform, caused by severe slippage.
- Despite holding over $50 million in aEthUSDT, the trader received merely 327 AAVE tokens, equivalent to roughly $36,000.
- The Aave platform displayed several explicit warnings about extraordinary slippage risks, which the trader acknowledged and proceeded past using a mobile device.
- An opportunistic MEV (Maximal Extractable Value) bot executed a sophisticated “sandwich attack,” extracting close to $10 million in gains from the transaction.
- In response to the incident, Aave has committed to refunding approximately $600,000 in protocol fees to the impacted trader.
In what has become one of the most expensive DeFi mistakes on record, a cryptocurrency trader experienced a devastating loss of nearly $50 million during a single swap transaction on Thursday, March 12, 2026. The incident occurred on Aave, a prominent decentralized finance protocol.
The involved wallet address contained $50,432,688 worth of aEthUSDT tokens, which had been transferred recently from Binance. These tokens represent an interest-generating version of Tether’s USDT stablecoin that had been deposited into Aave’s lending system operating on the Ethereum blockchain.
The trader initiated a swap to exchange the entire balance for aEthAAVE, which is a tokenized form of Aave’s native governance token. This transaction was processed through CoW Protocol with execution via the SushiSwap decentralized exchange platform.
Due to the massive order size relative to the available liquidity in the trading pool, the transaction suffered from extreme slippage exceeding 99%. The final result left the wallet holding a mere 327 AAVE tokens with a market value of only $36,000.
This translated to an effective price of approximately $154,000 for each AAVE token, while the prevailing market rate stood at just $114 per token.
What the Warnings Said
Stani Kulechov, the founder of Aave, verified that the platform’s user interface had displayed clear warnings prior to transaction execution. In a post shared on X, he explained that the system alerted the user about “extraordinary slippage” resulting from the “unusually large size of the single 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 Aave interface, like most trading interfaces, warned the user about extraordinary slippage and required confirmation via a checkbox.…
— Stani.eth (@StaniKulechov) March 12, 2026
To proceed, the trader was required to manually select a confirmation checkbox acknowledging the risk disclosure. This action was completed on a mobile device, and the user moved forward with executing the swap.
“The transaction could not be moved forward without the user explicitly accepting the risk,” Kulechov said. He added that the CoW Swap routers worked as intended.
CoW DAO released its own statement emphasizing that “no DEX, DEX aggregator, public liquidity pool, or private liquidity pool would have been able to fill this trade at anywhere near a reasonable price.”
Statement from CoW Protocol:
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
— CoW DAO (@CoWSwap) March 13, 2026
The MEV Bot Attack
Compounding the already disastrous slippage losses, a sophisticated MEV bot deployed a “sandwich attack” strategy against this transaction.
These automated MEV bots constantly scan blockchain networks for pending transactions. Upon detecting the substantial AAVE purchase order, the bot immediately positioned itself to extract profit.
The bot’s strategy involved flash-borrowing $29 million worth of wrapped Ether from the Morpho protocol, using those funds to purchase AAVE tokens on Bancor to artificially inflate the price, then liquidating those holdings directly into the user’s order on SushiSwap. This manipulation generated approximately $9.9 million in profit for the bot operator.
By front-running the transaction, the attack artificially elevated AAVE’s price immediately before the user’s order executed, significantly amplifying the already catastrophic outcome.
This incident occurred mere days following approximately $27 million in liquidations on Aave, which some industry observers suggested might have been connected to a temporary pricing anomaly involving the wstETH token.
Kulechov expressed that Aave has empathy for the affected trader. The protocol has announced plans to contact the user and reimburse roughly $600,000 in fees that were collected during the transaction.
CoW DAO similarly committed to refunding all protocol fees associated with the trade.
