Equilibrium open interest

Abstract

This paper analyses what determines an individual investor's risk-sharing demand for options and, aggregating across investors, what the equilibrium demand for options. We find that agents trade options to achieve their desired skewness; specifically, we find that portfolio holdings boil down to a three-fund separation theorem that includes a so-called skewness portfolio that agents like to attain. Our analysis indicates also, however, that the common risk-sharing setup used for option demand and pricing is incompatible with a stylized fact about open interest across strikes.