In a seminal study, Elton and Gruber (1970) argue that ex-dividend day pricing can be used to infer marginal tax rates of shareholders. We examine ex-dividend day pricing for individual firms and ask whether their CFOs could use the history of a firm's ex-dividend price-drop ratios to infer reasonable estimates of shareholders' marginal tax rates. We use TAQ data for 1,124 US firms that have at least 30 ex-dividend days during the period August 1993 to October 2012. Our results show that ex-dividend day pricing is so noisy as to prohibit sensible estimates of shareholders' marginal tax rates.