Short interest is reported daily. You don't have to do much guess work to know who is short, in general. And funds have to report beneficial ownership above cer

Short interest is reported daily. You don't have to do much guess work to know who is short, in general. And funds have to report beneficial ownership above certain thresholds, so highly concentrated "tactical" managers are susceptible to news or sentiment driven herd events involving stocks in which they have large positions.