Hong, HarrisonRex, Hunter2016-07-112026-09-292016-07-112026-09-292016-04-132016-07-11http://arks.princeton.edu/ark:/88435/dsp017w62fb66hhttps://theses-dissertations.princeton.edu/handle/88435/dsp017w62fb66hRecent work in the industrial organization literature nds a signi cant relationship between increased levels of institutional ownership among natural competitors and higher product prices in certain industries. We extend this framework to quarterly cross-sections of the U.S. economy using industry-level concentration measures of publicly-traded companies. Panel analyses identify a signi cant positive e ect of both common ownership concentration and its lags on industry average gross pro ts when controlling for xed e ects. We implement a panel-IV strategy using changes in large index funds' industry ownership levels to address endogeneity concerns and suggest a causal link from increased common ownership to higher industry gross pro t margins.50 pagesen-USPrinceton University Senior Theses