Capital asset pricing models predict the tax penalty capitalized into expected returns reflects the average tax rate of all investors in a market (average rate theory). To test this theory, I argue stock markets in developed European countries and the U.S. form an integrated market, where the tax capitalized reflects the average rate of investors across these countries. If this is the case, when the U.S. dividend tax rate was cut by 60 percent in 2003, the average rate theory predicts a decrease in the tax capitalized in European stocks. In contrast, firms in less integrated European countries should react significantly less to the U.S. tax cut. Finally, I test a prediction from Desai and Dharmapala (2011) that because of market integration the magnitude of the reaction to the tax cut should be the same for firms in the U.S. and developed European countries. The results in this paper support these predictions.