The $50M Swap That Exposed a Costly Slippage Mistake No Trader Saw Coming

Despite clear warnings, a trader confirmed a massive $50M swap and received just 324 Aave tokens

A user attempted to purchase the AAVE token with $50 million worth of Tether through the Aave interface on March 12, but the trade executed poorly after the user accepted a warning about extreme slippage.

According to Aave Labs founder and CEO Stani Kulechov, the transaction involved a single order of significant size placed through the Aave interface, which integrates routing infrastructure provided by CoW Swap. Because of the unusually large order size, the interface displayed a warning about extraordinary slippage and required explicit confirmation before the swap could proceed.

$50M Trade Gone Wrong

The warning appeared as a confirmation checkbox, which the user had to manually accept before completing the transaction. Kulechov said the user confirmed the warning on a mobile device and chose to proceed with the trade despite the slippage notification. Due to the execution conditions and the liquidity available through the routing path, the user ultimately received only 324 AAVE tokens in return for the $50 million USDT order.

Kulechov stated that the transaction could not have moved forward without the user explicitly acknowledging the warning and confirming acceptance of the associated risks through the interface. He said the routing infrastructure functioned as designed and that the integration with CoW Swap followed standard practices commonly used across the DeFi sector.

However, the final execution was significantly worse than what would typically be expected in a more liquid market environment. Kulechov noted that events involving high slippage can occur in DeFi when users attempt to execute trades that are far larger than the liquidity available in the relevant markets, although he said the scale of this specific transaction was significantly larger than what is normally seen in the space.

In response to the incident, the exec said the Aave team sympathizes with the user and will attempt to establish contact with them. He added that the protocol plans to return approximately $600,000 in fees that were collected from the transaction. Kulechov said that while maintaining the permissionless nature of DeFi remains important, the industry can still build additional guardrails to help reduce the likelihood of similar incidents in the future.

User Freedom vs Protection

CoW Protocol, which is a DEX aggregator, took to X and explained that “preventing users from making trades removes choice and can lead to terrible outcomes in some situations.” It also added that trades like these demonstrate that “DeFi UX still isn’t where it needs to be to protect all users. As a team, we are now reviewing how we balance strong safeguards with preserving user autonomy.”

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The platform asserted that it will refund any fees sent to CoW DAO.

The incident quickly drew reactions across the crypto community. A popular crypto analyst, Autism Capital, described the event as a “teachable moment about money.”

Meanwhile, another crypto commentator, KJ Crypto, questioned the motivation behind such a large purchase attempt and tweeted that it raises questions about why someone would want to acquire $50 million worth of Aave in a single transaction.