Convertible debt eliminates asset substitution in a one-period setting (Green, 1984). But convertible debt terms are usually set before the asset substitution opportunity. This allows shareholders and convertible debtholders to play a strategic noncooperative game. Two risk-shifting Nash equilibria are attainable: pure asset substitution when, despite no conversion, shareholders benefit from shifting risk, and strategic conversion when, despite early conversion, convertible debtholders expropriate wealth from straight debtholders. Even when initial convertible debt is designed to minimize the risk-shifting likelihood, the risk of asset substitution remains economically substantial ??? contrasting with the agency theoretic rationale for issuing convertible debt.