Testing the Theory of Common Stock Ownership

79 Pages Posted: 3 Aug 2020

See all articles by Lysle Boller

Lysle Boller

Duke Economics Department

Fiona M. Scott Morton

Yale School of Management; National Bureau of Economic Research (NBER)

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Date Written: July 6, 2020


We test if an increase in common ownership changes future expected profits with an event study method. We collect instances of stocks entering the S&P500 and identify their product market competitors. We measure changes in institutional and common ownership (with product market rivals) and find that entering firms experience a significant increase in both. We measure the stock returns of the entrants' product market rivals upon the entry news. We find that increases in common ownership (driven by the whole vector of ownership similarity) cause increases in stock returns, consistent with a hypothesis that common ownership raises profits.

Keywords: common ownership, horizontal shareholding

Suggested Citation

Boller, Lysle and Scott Morton, Fiona M., Testing the Theory of Common Stock Ownership (July 6, 2020). Available at SSRN: https://ssrn.com/abstract=3644036 or http://dx.doi.org/10.2139/ssrn.3644036

Lysle Boller

Duke Economics Department ( email )

100 Fuqua Drive
Durham, NC 27708-0204
United States

Fiona M. Scott Morton (Contact Author)

Yale School of Management ( email )

493 College St
New Haven, CT CT 06520
United States

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

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