This dissertation includes three essays on corporate disclosure and information externalities. In the first essay, I examine the disclosure behavior of rival firms identified by an Initial Public Offering (IPO) candidate during the IPO quiet period when the IPO candidate is restricted in its communication. I find that the tone of disclosures made by identified rivals becomes more positive during the quiet period, and reverses after the quiet period ends. The strategic disclosure behavior is mainly driven by identified rivals' concerns over product market competition. I also find that this behavior hurts the IPO candidate and benefits the identified rivals. In the second essay, I investigate the relations between IPO firms' peer choice and peer information environment. I find that IPO firms tend to select peer companies with a better information environment, and this effect is more pronounced for IPO firms with greater information uncertainties. I also find support that peer information environment is positively associated with upward offering price revision, post-offering analyst coverage, and negatively associated with the number of amendment filings. Overall, this essay shows that IPO firms can make use of the externalities of peer information to facilitate their initial public offerings. In the third essay, I switch my focus from intra-industry relations to supply chain relations. More specifically, I study the effects of layoff announcements by customers on the valuation and operating performance of their supply chain partners. I find that suppliers experience a negative stock price reaction around their major customers' layoff announcements. The negative price effect is exacerbated when industry rivals of layoff-announcing customers also suffer from negative intra-industry contagion effects. Moreover, these supply chain spillover effects are asymmetric, with only "bad news" layoff announcements causing significant value implications for suppliers, but not "good news" announcements. Supplier firms also reduce their investment in and sales dependence on layoff-announcing customers in subsequent years. Keywords: Disclosure; Product market competition; IPO quiet period; Identified rivals; Information externalities; Peer information environment; Corporate layoffs, Supply chain relations; Stock market return