We find wide dispersion in trade holding periods for institutional money managers and pension funds, using a large database of fund-level transactions. All of the institutional funds execute round-trip trades lasting over a year; 96% of them also execute trades lasting less than one month, although short duration trades have negative returns on average. We find only limited evidence that institutions choose trade holding periods based on portfolio optimization and no evidence that short-duration institutional trades are driven by the disposition effect. Our results are consistent with the agency problem that arises when clients cannot distinguish when a manager is “actively doing nothing” versus “simply doing nothing” as well as managers having overconfidence in their own short-term trading ability.