As cybercrimes continue to proliferate, average cybersecurity costs have increased to an all-time high. These ever-increasing costs have become a concern for investors. This concern is reflected in investors’ negative reactions in stock market due to data breach incidents. However, research has provided inconsistent evidence regarding how and to what extent data breach disclosures elicit negative market reactions. To provide fresh insights on this phenomenon, we focus on social media sentiment to empirically investigate the impact of data breach sentiment on the market reaction in light of two key factors: (1) breach source type and (2) news pressure. Our research is expected to offer useful explanations for the inconsistent evidence found in the extant literature.