In this study, Granger tests are used to examine the relationship between blockholder ownership and the values of the largest companies in the European Union and the US. Previous studies on US data have found that blockholder ownership has no systematic effect on performance. We propose that these results may not apply to Continental Europe, where ownership concentration is typically higher, the level of investor protection is lower, and influential blockholders may have objectives other than shareholder value. In accordance with previous research, we find no significant association between blockholder ownership and prior or subsequent firm value in either the US or the UK. Nonetheless, in Continental Europe we find a negative association between blockholder ownership and firm value or accounting returns in the next period. Further analysis reveals that this association is significant only for companies with high initial levels of blockholder ownership ( extgreater10%). We interpret this finding as evidence of conflicts of interest between blockholders and minority investors. The percentage of blockholder ownership in Continental Europe may be too high from a minority shareholder value viewpoint.