I investigate the relationship between the amount of information provided by a firm's comparables (i.e., firms in the same line of business as the firm being valued) and the precision of the firm's equity valuation. When investors have more information, previous studies argue that investors can make a more precise estimate of a firm's true equity value and this implies a lower (excess) stock return volatility around corporate events such as earnings announcements. I develop a simple model that shows a negative relationship between the amount of information provided by a firm's comparables and the firm's stock return volatility. Using alternative measures of information provided by comparables and different definitions of comparables, I consistently find a negative and significant relationship between these information measures and stock return volatility, ceteris paribus.