Thus, our estimate of institutional herding is triple that of previous studies. There are three possible reasons why our estimates of institutional herding are larger than previous estimates. First, we are analyzing herding at a monthly horizon rather than a quarterly horizon. Second, we are analyzing only the initiator of the trade. Third, we are estimating herding for only the largest trade size bin. Institutions that rely on large trades may herd more than all institutions in aggregate. For both large and small trades, we find evidence of coordinated trading within the month.