Supermartingale deflators in the absence of a numeraire

摘要

In this paper we study arbitrage theory of financial markets in the absence of a numeraire both in discrete and continuous time. In our main results, we provide a generalization of the classical equivalence between no unbounded profits with bounded risk and the existence of a supermartingale deflator. To obtain the desired results, we introduce a new approach based on disintegration of the underlying probability space into spaces where the market crashes at deterministic times.