The assumption of dynamic replication in no-arbitrage option pricing models does not hold in practice due to discreteness of trading hours as well as trading costs, which suggests the potential presence of preference-driven risk premiums. In this paper, we empirically show that discretely hedged S&P 500 index option portfolios are exposed to covariance and coskewness risk with the market portfolio. Using the three-moment CAPM of Kraus and Litzenberger (1976), we find that the rate of return of the portfolio significantly loads on the two risk factors, and their risk premiums are significantly positive. The equilibrium model complements the prevailing approach of the no-arbitrage framework, and reveals that the volatility smile is linked to investors’ preference on the unhedged market risks.