We find strong evidence that net insider selling is positively associated with future stock return volatility, consistent with insider selling increasing outside investors’ uncertainty. The positive effect of net insider selling is significantly stronger when the volatility is measured around the earnings announcement. Apparently, option prices do not fully reflect the information content of insider trading for future volatility. More specifically, we find no evidence that option traders adjust the implied volatility for the insider trading effect in a timely manner. Consequently, net insider selling is significantly associated with future option straddle returns and delta neutral returns.

Some firms voluntarily make disclosures about the controls and processes in place to ensure the reliability of fair value estimates. Consistent with these disclosures being driven by investors’ concerns about the reliability of their SFAS 157 estimates, we find that firms with more opaque estimates are more likely to provide such disclosures. We then examine whether these disclosures improve investors’ perception about the reliability of fair value estimates. We find that they are associated with higher market pricing and lower information risk for Level 3 estimates. Further analyses of the disclosures reveal that the following types of information are particularly important to investors: discussion of the external and independent pricing of fair value estimates and their proper classification according to the SFAS 157 hierarchy. Overall, our results suggest that the voluntary reliability disclosures that firms provide beyond SFAS 157’s three-level estimates help reduce investors’ uncertainty toward the more opaque fair value estimates.

We examine the association between corporate tax aggressiveness and the profitability of insider trading under the assumption that insider trading profits reflect managerial opportunism. We document that insider purchase profitability, but not sales profitability, is significantly higher on average in more tax aggressive firms. We also find that the positive association between tax aggressiveness and insider purchase profitability is attenuated for firms with more effective monitoring and is accentuated for firms with a more opaque information environment. In addition, we provide empirical evidence that tax aggressiveness is significantly associated with greater insider sales volume in the fiscal year prior to a stock price crash. Finally, we find that the association between tax aggressiveness and insider purchase profitability weakens after the introduction of FIN 48, consistent with the increased transparency of tax positions under the new disclosure requirement reducing insiders' information advantage and hence their ability to profit from insider trading. To the extent that insider trading profits reflect managerial opportunism, our results are consistent with managers exploiting the opacity arising from tax aggressive activities to extract rent from shareholders, particularly those shareholders who sold their shares to the managers. Our findings are particularly important in light of the number of studies relying on the agency view of tax avoidance to develop arguments or to draw inferences.