For market with an atomless continuum of assets, we formulate the intuitive idea of a well-diversified portfolio, and present a notion of exact arbitrage, strictly weaker than the more conventional notion of asymptotic arbitrage, and necessary and sufficient for the validity of an APT pricing...

We provide a detailed portfolio analysis for a financial market with an atomless continuum of assets. In the context of an exact arbitrage pricing theory (EAPT), we go beyond the characterization of the existence of important portfolios (normalized riskless, mean, cost, factor and mean-variance...