Arbitrage: Atomic, Cross-DEX, Cross-Chain

What you'll learn

• Arbitrage Is the Constructive Core of MEV
• Atomic Arbitrage: Same Block, Same Transaction
• Cross-DEX with Inventory: The Other 50%
• Cross-Chain Arbitrage: The Hardest Case
• Complete Atomic Arb Pseudocode

Key terms

Atomic arbitrage

Arbitrage executed in a single transaction — flash loan, swap, swap, repay — with the entire transaction reverting if any leg fails. Zero principal risk to the searcher; only gas is lost.

Flash loan

A loan that must be repaid in the same transaction. Aave V3 (0.05% fee), Balancer (free), MakerDAO, and Uniswap v3 callbacks all offer flash loans. Enables capital-free MEV extraction.

Inventory arbitrage

Arbitrage that requires the searcher to hold capital on both sides of the trade because the legs cannot execute atomically. Higher gross margin, higher risk; resembles market-making more than pure-play MEV.

Cross-chain arbitrage

Arbitrage across distinct blockchains, mediated by bridges or messaging protocols. Higher margins than intra-chain because competition is thinner, but exposed to bridge settlement risk.

Triangle arbitrage

Multi-hop atomic arbitrage involving three or more legs (e.g., USDC->WETH on Uniswap, WETH->stETH on Curve, stETH->USDC on Balancer). Larger search space; less crowded competition.

CEX/DEX arbitrage

Arbitrage between a centralized exchange (Binance, OKX) and a DEX (Uniswap, Curve). Operationally similar to cross-chain arb but the off-chain leg is on a CEX API rather than a bridge.

Across

A UMA-based cross-chain bridge with prefunded relayer liquidity. Typical 1-3 minute settlement; favored by cross-chain arb searchers for its speed/cost tradeoff.

Optimal arb size

The trade size that maximizes captured profit given the two pools' pricing curves. Smaller than draining the cheap pool entirely — because slippage grows with size — and solved analytically per pool type (constant product, stableswap, Balancer weighted).

Intent-based execution

A protocol model (CowSwap, UniswapX, Across) where users state a desired outcome and solvers compete to fulfill it. Wraps searcher-like infrastructure in a user-friendly interface that delivers better fills.