Do diversified investment vehicles―especially index funds―diminish competitive pressures in concentrated industries? There is an active (and contentious) debate among researchers, policymakers and practitioners about the costs and benefits of such “common ownership.”

In addition to a rapidly growing number of industry-level studies—looking at airlines (here and here), banking (here and here) and ready-to-eat cereals (Backus, Conlon and Sinkinson, forthcoming), or at broad groups of industries—other researchers have sought to link common ownership to macroeconomic phenomena, like the weakness of post-crisis investment. And, in response to anti-competitive claims, legal scholars propose using antitrust law to limit the holdings of institutional investors in oligopolistic industries. Against this background, competition authorities in Europe and the United States are taking the debate seriously (see, for example, the FTC hearing held in December at the NYU School of Law).

Our own view is that the discussion remains at a very early stage, and that it is likely to take years to resolve whether CO, especially through index-tracking mutual and exchange-traded funds, meets the cost-benefit test (for a skeptical view of CO, see here). Importantly, even if CO does reduce competitive pressures, we currently know far too little to about the scale or scope to identify remedies that would be most effective and least disruptive. Furthermore, should the case for broad-based anti-competitive effects become compelling, any response will need to consider the welfare trade-off between the very large consumer benefits arising from broad index funds and the consumer costs associated with a loss of competition in selected oligopolistic industries.

Against this background, we welcome two new papers (here and here) by Backus, Conlon and Sinkinson (BCS) that review the literature, provide new data to characterize the evolving pattern of share ownership, and suggest a back-to-basics approach for testing the CO hypothesis in specific industries. We hope that their work will spur a wave of CO research that will help us weigh the increasingly animated claims and counter-claims. In the remainder of this post, we highlight a few of the lessons from this recent research….