This paper investigates the influence of firm-specific investor sentiment on stock price informativeness in China. Using a composite firm-specific investor sentiment index, we find that sentiment positively influences stock price synchronicity and future price crash risk for opaque stocks. We use firm-specific investor sentiment proxy to develop a market sentiment proxy, which could predict aggregate price synchronicity beyond extant market sentiment indicators. Our results suggest that the composite sentiment index is a reliable proxy and investor sentiment negatively affects price informativeness.