Routing Error Turns $2M ETH Swap Into $14K as Same-Block Backrun Captures Value

A large decentralized exchange swap that began with about 1,126 ETH (roughly $2.01 million) ended with the trader receiving only 5,775.66 LIT tokens worth around $14,500, after the trade was routed through a near-empty AVAIL/WETH pool and then backrun in the same Ethereum block. GoPlus Security said the incident was not a typical sandwich attack, describing it as a "textbook case of same-block backrun extraction." On-chain traces shared by the firm show 1,116.8661 ETH was swapped for roughly 6.68 million AVAIL on Uniswap V3 at an extreme price due to thin liquidity. The AVAIL was then converted into about 14,508 USDC and ultimately into 5,775.66 LIT on Uniswap V4, leaving the final on-chain proceeds valued near $14.5K. In the same block, a searcher identified the distorted pricing and executed an arbitrage. The bot spent about 0.3942 WETH to buy 2,154 AVAIL elsewhere, then sold that AVAIL into the inflated AVAIL/WETH pool, extracting most of the ETH that had just been added. GoPlus estimated the backrun pulled about 1,072.46 WETH from the pool, with 1,018.25 ETH sent to Titan Builder as a builder payment. GoPlus noted Titan Builder captured the largest share of value from the event, though funds were not taken directly from the victim's wallet. The loss was driven by routing a large order into a low-liquidity pool, creating a severe price imbalance. GoPlus said the trader effectively bought AVAIL at roughly 120x the post-arbitrage market price. Because only a small, correctly priced countertrade was needed to restore the pool's price, the arbitrageur was able to withdraw nearly all the newly contributed ETH by selling a relatively small amount of AVAIL. Trader and crypto commentator Ruslan Khairullin said the episode highlights the need to review the execution route of DEX transactions, not just the quoted output, before approving a swap. The incident also underscores the influence of searchers and block builders in today's MEV landscape. According to DeFiLlama data cited in related coverage, Titan Builder has generated about $112.6 million in block-building revenue so far this year, with its largest single-day gain in March at roughly $34 million from an MEV event involving CoW Protocol. The takeaway: thin-liquidity pools and same-block MEV extraction remain persistent DeFi risks, and large traders face outsized exposure when routing paths and slippage protections are not carefully checked. In current market conditions, a single routing mistake can reduce a seven-figure swap to a fraction of its intended value.