Institutional segmentation of equity markets: causes and consequences

We re-examine the determinants of institutional ownership (IO) from a segmentation perspective -- i.e. accounting for a hypothesized systematic exclusion of stocks that cause high implementation or agency costs. Incorporating segmentation effects substantially improves both explained variance in IO and model parsimony (essentially requiring just one input: market capitalization). Our evidence clearly establishes a role for both implementation costs and agency considerations in explaining segmentation effects. Implementation costs bind for larger, less diversified, and higher turnover institutions. Agency costs bind for smaller institutions and clienteles sensitive to fiduciary diligence. Agency concerns dominate; characteristics relating to the agency hypothesis have far more explanatory power in identifying the cross-section of segmentation effects than characteristics relating to the implementation hypothesis. Importantly, our study finds evidence for interior optimum with respect to the institution's scale, due to the counteracting effect between implementation and agency frictions.

We then explore three implications of segmentation for the equity market. First, a mass exodus of publicly listed stocks predicted to fall outside institutions' investable universe helps explain the listing puzzle. There has been no comparable exit by institutionally investable stocks. Second, institutional segmentation can lead to narrow investment opportunity sets, which limit money managers' ability to take advantage of profitable opportunities outside their investment segment. In this respect, we construct pricing factors that are feasible (ex-ante) for institutions and benchmark their performance. We find evidence consistent with the demand-based asset pricing view. Specifically, IO return factors yield higher return premia and worsened institutional performance relative to standard benchmarks in an expanding institutional setting (pre-millennium). Third, we use our logistic model and examine the effect of aggregated segmentation on the institutions' portfolio returns. Our findings suggest that investment constraints cut profitable opportunities and restrict institutions from generating alpha. In addition, we find that stocks with abnormal institutional ownership generate significant positive returns, suggesting institution actions are informed.