Why Cross-Chain MEV Will Be Captured by Bundlers

Bundlers own the atomic transaction flow. They construct, order, and submit user bundles, giving them the first and most comprehensive view of cross-chain intent. This privileged position is structurally superior to bridges like Across or Stargate, which only see a single asset transfer.

Intent-based architectures centralize opportunity. Protocols like UniswapX and CowSwap abstract execution to solvers, who are sophisticated bundlers. This creates a natural funnel where all cross-chain swap intents become visible to a few professional operators.

Cross-chain messaging is the attack surface. Systems like LayerZero and CCIP enable atomic compositions across chains. The entity that controls the sequencing of these messages—the bundler—captures the arbitrage and liquidation opportunities they create.

Evidence: Over 90% of Ethereum MEV is captured by five entities. This concentration will replicate in cross-chain, as the technical requirements for latency and capital scale favor professional bundlers over retail users.

Bundlers own the execution layer. Intent-based systems like UniswapX and CowSwap abstract transaction construction. The user submits a desired outcome, and a bundler's private mempool determines the optimal, often cross-chain, execution path. This centralizes routing logic and fee extraction.

Cross-chain is the ultimate MEV frontier. Single-chain MEV is a solved, competitive market. The real value is in atomic cross-domain arbitrage between chains like Ethereum and Solana, which requires coordination only a bundler's infrastructure can provide.

Bundlers become the new sequencers. Just as L2 sequencers profit from ordering, bundlers profit from intent interpretation. They will integrate with bridges like Across and LayerZero not as equals, but as clients, internalizing the bridging fee and MEV.

Evidence: The 4337 standard enshrines this. ERC-4337's architecture makes the bundler a trusted third party for all UserOperations. This is not a bug; it is the design. The entity that fills your intent captures its surplus value.

Bundlers control atomic execution. They are the only entities that can sequence and submit the multi-chain transaction bundle, guaranteeing its success or failure as a single unit. This position is structurally superior to individual searchers or bridges.

Intent-based architectures centralize flow. Protocols like UniswapX and CowSwap route user intents through solvers. The winning solver, often a bundler, captures the cross-chain arbitrage or routing value within the solved bundle.

Cross-chain messaging is the bottleneck. Finalizing a bundle requires secure message passing via protocols like LayerZero or Axelar. The bundler that pays for and orchestrates this attestation owns the economic outcome.

Evidence: Over 80% of intents on UniswapX are filled by just five solver addresses, demonstrating the natural centralization of complex, multi-step execution.

Specialized searchers win on latency. A general-purpose bundler must wait for user intent to arrive. A cross-chain MEV searcher, like those using Flashbots SUAVE or Jito, proactively scans for opportunities across chains, submitting the profitable bundle first.

Economic incentives are misaligned. A bundler's fee is a small, predictable cut of a user's gas. A cross-chain arbitrage bundle's profit is the entire spread between Uniswap on Arbitrum and Curve on Base, creating orders-of-magnitude larger rewards for searchers.

Technical complexity favors specialization. Executing a profitable cross-chain swap requires atomic coordination of actions on the source chain, a LayerZero or Axelar message, and a destination-chain swap. This is a full-time operation, not a side-task for an ERC-4337 bundler.

Evidence: The 51% of Ethereum MEV captured by searchers proves specialization beats generalization. This dynamic will repeat, with entities like Across Protocol's relayers or Chainlink's CCIP oracles becoming the de facto cross-chain execution layer.