Critical dimensions in the empirical measurement of common shareholding

The debate on common shareholding - and its potential antitrust effects - is currently on theagenda of all major institutions worldwide. All discussions point to the need for improved empiricalquantification in order to assess potential impacts. This work presents a unifying statistical framework for a series of common shareholding indices, with detailed mathematical properties. The framework includes indices coming from both sparse matrix theory as well as from network analysis. The proposed indices are based on balance-sheet and ownership firm-level data, and cover both the firm’s and the investor’s perspectives. They are then aggregated at market level to obtain suitable industry indicators. The measures are tested using firm-level data for European Mobile Network Operators between 2007-2019, with special attention dedicated to the role of the largest investors. Many of the indicators currently used in the literature can be identified as special cases falling within this framework