On March 12, 2026, a checked box swap Aave was enough to validate an exchange of 50 million dollars in USDT for AAVE tokens, despite an explicit warning of extraordinary slippage displayed before confirmation. The user received only 324 AAVE in return, worth roughly 36,000 dollars, as confirmed by Aave founder Stani Kulechov on X the same day.
What the checked box actually validated
According to Stani Kulechov, Aave’s interface functioned exactly as intended when facing an 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 Aave interface, like most trading interfaces, warned the user about extraordinary slippage and required confirmation via a checkbox,” he wrote (post on X, March 12, 2026). The transaction could not proceed unless the user checked this risk acceptance box themselves.
The user confirmed this warning from a mobile device before the swap executed. “The user confirmed the warning on their mobile device and proceeded with the swap, accepting the high slippage, which ultimately resulted in receiving only 324 AAVE in return,” Stani Kulechov states in the same post. He adds that routing through CoW Swap worked as intended: “The CoW Swap routers functioned as intended.”
The math behind the 50 million dollar loss
News outlet The Block reports that CoW Swap confirmed the order executed according to its signed parameters: “The transaction executed according to the parameters of the signed order” (The Block, March 12, 2026). An Aave engineer quoted by Decrypt, relayed by Yahoo Finance, clarifies where the real issue lay: “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” (Decrypt via Yahoo Finance, March 12, 2026).
In other words, the accepted slippage tolerance of 1.21% allowed for an execution price slightly different from the displayed price, but the quote itself already carried a 99% price impact before fees, a direct consequence of the order’s size relative to the liquidity available on that market at that exact moment. The same source quantifies the effective loss: “At a current market price of $111.52, the tokens are worth roughly $36,100, implying an effective loss of about $49.96 million relative to the original order size.”
| Item | Value | Date |
|---|---|---|
| Amount sent in USDT | 50,000,000 dollars | March 12, 2026 |
| AAVE received | 324 tokens | March 12, 2026 |
| Value of AAVE received | roughly 36,100 dollars | March 12, 2026 |
| Displayed and accepted slippage | 1.21% | March 12, 2026 |
| Actual price impact of the quote | roughly 99% | March 12, 2026 |
| Estimated effective loss | roughly 49.96 million dollars | March 12, 2026 |
Aave’s response after the incident
Stani Kulechov announced an attempt to contact the user and a limited financial gesture: “We sympathize with the user and will try to make a contact with the user and we will return $600K in fees collected from the transaction” (post on X, March 12, 2026). This refund of 600,000 dollars corresponds to the fees collected on the transaction, not to the total loss suffered, which the protocol did not promise to cover.
This case illustrates a mechanism specific to decentralized exchanges built on aggregated order books, where a single order disproportionate to available liquidity can produce an extreme quote despite an explicit warning. This mechanism does not describe how CFDs or the foreign exchange market work, where slippage on CFDs and Forex follows a different execution logic, just as a stop-loss trigger order on these markets follows distinct rules.
Frequently asked questions about this incident
Why did Aave’s interface allow the transaction to go through?
The interface displayed a warning of extraordinary slippage and required explicit confirmation through a checkbox before executing the order. According to Stani Kulechov, the transaction could not proceed without this manual risk acceptance by the user themselves.
Was the user refunded for the loss?
No. Aave announced it would refund the 600,000 dollars in fees collected on the transaction, but not the total loss estimated at roughly 49.96 million dollars. The protocol said it would try to contact the user involved.
Was the problem caused by the accepted 1.21% slippage?
No, according to an Aave engineer quoted by Decrypt. The displayed slippage of 1.21% was not the main cause: the accepted quote already carried a 99% price impact before fees, a consequence of the order’s size relative to available liquidity.
Can this type of incident happen on a CFD or in Forex?
The mechanism described here is specific to decentralized exchanges and their aggregated quote model. It does not document how CFDs or Forex work, where price slippage follows different execution rules.