The Securities and Exchange Commission requires publicly held US corporations to disclose all information, whether it is positive or negative, that might be relevant to an investor's decision to buy, sell, or hold a company's securities. The decisions made by corporate managers to disclose such information can significantly affect the judgments and decisions of investors. This paper examines academic accounting research on corporate managers' voluntary disclosures of earnings forecasts and non-GAAP earnings measures. Much of the evidence from this research indicates (...) that some managers engage in opportunistic disclosure behavior that often benefits one group (managers and shareholders) at the expense of other groups (often other investors). The paper concludes by discussing the ethical implications of this behavior. (shrink)