This dissertation consists of four self-contained chapters that examine merger & acquisition (M&A) press releases (PRs) and firm performance. The central research topic with regard to M&A PRs is to investigate the relationship between the textual properties of PRs and the firm’s short-term and long-term performance. The first chapter reviews studies related to firms’ M&A activities and disclosures. The second chapter investigates whether the textual properties of M&A PRs trigger the price and volume reaction of both acquiring and target firms, which is the short-term market reaction during the announcement period. The third chapter focuses on the long-term performance of the acquirer after the completion of the M&A deal. This chapter examines whether the textual properties of M&A PRs predict the acquirer’s performance several years after the completion of the deal. The fourth chapter investigates the acquirer’s earnings management activities and how these activities affect the textual properties of M&A PRs.