We study the relationship between stock price synchronicity and information disclosure of firms listed in the Chinese stock market, using hand-collected data on firms’ official microblogging content in Sina Weibo, a popular microblogging service in China. We find that after controlling for the impact of traditional media, the number of Weibo tweets is related negatively to stock price synchronicity, indicating that stock prices incorporate firm-specific information disclosed in the firm’s official Weibo. Number of microblogging fans can strengthen this negative relationship. Our result is robust to alternative measures of stock price synchronicity, microblogging information disclosure, and to endogeneity issues.