Non-atomic arbitrage on Ethereum DEXes is a type of maximal extractable value (MEV) that exploits price differences between DEXes on the Ethereum blockchain and off-chain markets, such as centralized exchanges (CEXes) or DEXes on other blockchains. This study reveals that over a fourth of the volume on Ethereum’s five largest DEXes from the merge until 31 October 2023 is likely non-atomic arbitrage. Eleven searchers account for over 80% of this volume, totaling $132 billion, highlighting the centralization of the block construction market. Non-atomic arbitrage is linked to high cryptocurrency price volatility, with builders specializing in this type of arbitrage more likely to be selected during such periods. The study introduces a model to quantify profits from non-atomic arbitrage and identifies that non-atomic arbitrage trades are more prevalent than previously thought. The analysis shows that non-atomic arbitrage is closely tied to price volatility, with significant increases observed during events like the FTX bankruptcy and the USDC depeg. The volume of non-atomic arbitrage trades is highly correlated with the volatility of ETH and BTC, with correlations of 0.725 and 0.729 respectively. The volume also peaks during market hours, particularly during US, Asian, and European market openings, and on Wednesdays around 18:00 UTC, coinciding with major financial events. The study also highlights that non-atomic arbitrage is often executed by integrated searchers, where the same entity controls both the searcher and the builder. This centralization raises concerns about the security implications of high-value transactions that account for over 10% of Ethereum’s total block value. The findings suggest that non-atomic arbitrage is a significant and growing concern in the DeFi ecosystem, with potential mitigations needed to address the centralization and security risks associated with this type of MEV.Non-atomic arbitrage on Ethereum DEXes is a type of maximal extractable value (MEV) that exploits price differences between DEXes on the Ethereum blockchain and off-chain markets, such as centralized exchanges (CEXes) or DEXes on other blockchains. This study reveals that over a fourth of the volume on Ethereum’s five largest DEXes from the merge until 31 October 2023 is likely non-atomic arbitrage. Eleven searchers account for over 80% of this volume, totaling $132 billion, highlighting the centralization of the block construction market. Non-atomic arbitrage is linked to high cryptocurrency price volatility, with builders specializing in this type of arbitrage more likely to be selected during such periods. The study introduces a model to quantify profits from non-atomic arbitrage and identifies that non-atomic arbitrage trades are more prevalent than previously thought. The analysis shows that non-atomic arbitrage is closely tied to price volatility, with significant increases observed during events like the FTX bankruptcy and the USDC depeg. The volume of non-atomic arbitrage trades is highly correlated with the volatility of ETH and BTC, with correlations of 0.725 and 0.729 respectively. The volume also peaks during market hours, particularly during US, Asian, and European market openings, and on Wednesdays around 18:00 UTC, coinciding with major financial events. The study also highlights that non-atomic arbitrage is often executed by integrated searchers, where the same entity controls both the searcher and the builder. This centralization raises concerns about the security implications of high-value transactions that account for over 10% of Ethereum’s total block value. The findings suggest that non-atomic arbitrage is a significant and growing concern in the DeFi ecosystem, with potential mitigations needed to address the centralization and security risks associated with this type of MEV.