This paper presents evidence that the reduction in option tick size enhances equity price efficiency. To address the endogeneity issue, I employ an exogenous event, namely the Penny Pilot program. The findings indicate that option trading mitigates equity misvaluation, reduces price delay, accelerates the incorporation of future earnings into equity prices, and eliminates the well-known Post-Earnings Announcement Drift (PEAD). The pilot program significantly increases trading volume and reduces trading costs during the pilot period. Furthermore, the effect of options-to-stock volume on future stock returns is stronger in firms with high short-sale costs. This evidence is consistent with the hypothesis that informed trading boosts trading volume in the options market and integrates information from the options market into equity prices, thereby enhancing equity price efficiency.

This paper proposes a novel channel through which innovation externalities can affect firm performance. I find cross-sectional evidence that the positive innovation outputs of customer firms increase their supplier profitability as measured by firm ROE. This result is robust to the inclusion of industry fixed effect, a control for both supplier and customer characteristics, such as ROE, advertisement expenditure, capital expenditure, firm age, industry concentration, institutional ownership, dividend yield, and a control for industry spillover or geographical spillover. To identify the causal effect of customer innovation outputs on supplier performance, I study an exogenous shock—State Street Bank and Trust Company v. Signature Financial Group, Inc.—and find that an increase in granted customer patents causes an improvement in future supplier performance. This effect is mainly driven by the demand channel and the knowledge diffusion channel from customers to suppliers.

Using a difference-in-differences approach that relies on the exogenous increase in options trading activity generated by the Securities and Exchange Commission's Penny Pilot Program, we find a negative causal effect of options trading on earnings management. With a reduced magnitude of discretionary accruals, the pilot firms are less likely to marginally beat earnings targets and less likely to have financial misstatements during the pilot period. Cross-sectional analysis shows that the effects are more pronounced among firms with a small or less independent board or a small audit committee. Furthermore, the pilot firms receive more market attention, and their stock price efficiency improves more than the nonpilot firms during the pilot period. The evidence is consistent with the argument that active options trading enhances market scrutiny of firms' reporting behavior, improving financial reporting quality and price efficiency.