AbstractWe examine the effect of options trading on an optioned firm's investment decisions. We find that active options trading improves an optioned firm's investment efficiency, and that this effect holds under several alternative empirical specifications and identification strategies, including fixed‐effects models, different matching methods, an instrumental variable approach, a Granger causality test and a quasi‐natural experiment based on the listing decisions of the options exchanges. This relation is mediated by two factors, namely, information asymmetry and uncertainty, consistent with the notion that options trading improves investment efficiency by providing information that facilitates external monitoring and managerial learning. The results of cross‐sectional analyses indicate that the effect of options trading on investment efficiency increases with firms’ tendency to overinvest or underinvest, and with managers’ risk‐taking and learning incentives. We also demonstrate that the effect of options markets on investment efficiency is distinct from the effect of stock markets. Overall, our findings suggest that options trading plays a nonnegligible role in improving an optioned firm's investment efficiency.