Despite the common perception that institutional investors herd, it is difficult to identify the reasons for correlated trading. For example, managers might buy into or out of the same securities over some period due to correlated information, perhaps from analyzing the same indicator. Alternatively, a manager might infer private information from the prior trades of better-informed managers and trade in the same direction. Also, managers might disregard their own information and trade with the crowd due to the reputational risk of acting differently from other managers. Finally, managers might simply have correlated preferences over certain types of securities.
In a recent paper, I study correlated trading by Colombian pension fund managers in the presence of a peer-based underperformance penalty known as the Minimum Return Guarantee (MRG). The MRG resembles a reputational risk, in that the manager might be penalized for having lower returns than her peers. With the MRG, the risk is explicit as the manager will be penalized financially if returns are below the maximum allowed shortfall relative to the peer benchmark. The rationale for the MRG, which is a common piece of the regulation in defined contribution pension systems, is to discourage excessive risk taking by pension fund managers.