Loose Definition of Arbitrage: A trading strategy that earns something from nothing, no matter how the market evolves in the future. No-arbitrage pricing.Arbitrage pricing theory (APT) is an alternative to the capital asset pricing model (CAPM) for explaining returns of assets or portfolios. Arbitrage-free valuation is the value of an asset or financial instrument based solely on the real performance or cash flows that it generates. A market model is arbitragefree if and only if it has a riskneutral probability measure. This is the fundamental theorem of asset pricing. "Arbitrage and Use of Proceeds Certificate" means the Arbitrage and Use of Proceeds. If markets are complete, under no arbitrage there exists a unique valuation functional.