This paper provides a theoretical derivation of commodity beta (stock price sensitivity to commodity price) using a contingent-claim model. The model incorporates operating leverage, financial leverage, costly financial distress, and mean reverting commodity prices; and highlights the important role played by the speed of reversion of the commodity price. It is used to identify theoretically the main determinants of commodity beta. Commodity beta is predicted to be an increasing function of the operating and financial leverage of the firm, and a decreasing function of the company’s tax rate and the level, volatility and speed of reversion of the commodity price. Empirical tests with a sample of gold mining firms provide support for these predictions, particularly the new implications of the model (the effect of the commodity price’s speed of reversion and the company’s tax rate).

This paper computes the effective duration of callable corporate bonds, using a contingent-claims model that incorporates both default risk and call risk. The model generates empirical implications regarding the cross-sectional variation and the firm-specific determinants of duration, and demonstrates that the effect of the call feature is to shorten duration (except for low-grade bonds). The effective duration is also estimated empirically for a large sample of long-term corporate bonds, using monthly bond price and interest rate data. Cross-sectional regression analysis is used to test the empirical implications of the model regarding the determinants of effective duration, and the empirical results are quite supportive of the model’s predictions.