Communities in Italian corporate networks

The community structure of two real-world financial networks, namely the board network and the ownership network of the firms of the Italian Stock Exchange, is analyzed by means of the maximum modularity approach. The main result is that both networks exhibit a strong community structure and, moreover, that the two structures overlap significantly. This is due to a number of reasons, including the existence of pyramidal groups and directors serving in several boards. Overall, this means that the “small world” of listed companies is actually split into well identifiable “continents” (i.e., the communities).

[1]  D. Mason,et al.  Compartments revealed in food-web structure , 2003, Nature.

[2]  Albert-László Barabási,et al.  Statistical mechanics of complex networks , 2001, ArXiv.

[3]  Vladimir Batagelj,et al.  Pajek - Analysis and Visualization of Large Networks , 2001, Graph Drawing Software.

[4]  Rosanna Grassi,et al.  Shareholding Networks and Centrality: An Application to the Italian Financial Market , 2009 .

[5]  R. Morck.  A History of Corporate Governance around the World: Family Business Groups to Professional Managers , 2005 .

[6]  E A Leicht,et al.  Community structure in directed networks. , 2007, Physical review letters.

[7]  S. Strogatz.  Exploring complex networks , 2001, Nature.

[8]  V. Latora,et al.  Complex networks: Structure and dynamics , 2006 .

[9]  Peter Sheridan Dodds,et al.  Information exchange and the robustness of organizational networks , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[10]  Duncan J. Watts,et al.  The Structure and Dynamics of Networks: (Princeton Studies in Complexity) , 2006 .

[11]  S. Bornholdt,et al.  When are networks truly modular , 2006, cond-mat/0606220.

[12]  Corporate board network and information flows in the Italian Stock Exchange , 2008 .

[13]  M E J Newman,et al.  Modularity and community structure in networks. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[14]  M E J Newman,et al.  Finding and evaluating community structure in networks. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[15]  Florencio López‐de‐Silanes,et al.  Law and Finance , 1996, Journal of Political Economy.

[16]  Stefano Battiston,et al.  Inner structure of capital control networks , 2004 .

[17]  S Battiston,et al.  Backbone of complex networks of corporations: the flow of control. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[18]  G. Davis,et al.  Corporate Elite Networks and Governance Changes in the 1980s , 1997, American Journal of Sociology.

[19]  Maurizio Zollo,et al.  Small worlds evolving: governance reforms, privatizations, and ownership networks in Italy , 2006 .

[20]  Guido Caldarelli,et al.  The corporate boards networks , 2004 .

[21]  D. Garlaschelli,et al.  The scale-free topology of market investments , 2003, cond-mat/0310503.

[22]  Larry H. P. Lang,et al.  The Ultimate Ownership of Western European Corporations , 2002 .

[23]  R. K. Shyamasundar,et al.  Introduction to algorithms , 1996 .

[24]  Roger Guimerà,et al.  Module identification in bipartite and directed networks. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[25]  Stefano Battiston,et al.  The Network of Inter-Regional Direct Investment stocks across Europe , 2007, Adv. Complex Syst..

[26]  S. Battiston,et al.  Statistical properties of corporate board and director networks , 2004 .

[27]  H. Kunzi,et al.  Lectu re Notes in Economics and Mathematical Systems , 1975 .

[28]  Mark E. J. Newman,et al.  The Structure and Function of Complex Networks , 2003, SIAM Rev..

[29]  William M. Rand,et al.  Objective Criteria for the Evaluation of Clustering Methods , 1971 .

[30]  Claudio Castellano,et al.  Community Structure in Graphs , 2007, Encyclopedia of Complexity and Systems Science.

[31]  M. Newman.  Analysis of weighted networks. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[32]  Larry H. P. Lang,et al.  The Separation of Ownership and Control in East Asian Corporations , 1999 .

[33]  Albert-László Barabási,et al.  Evolution of Networks: From Biological Nets to the Internet and WWW , 2004 .

[34]  Gerald F. Davis,et al.  The Significance of Board Interlocks for Corporate Governance , 1996 .

[35]  Ariane Chapelle,et al.  Separation between Ownership and Control: Where Do We Stand? , 2004 .

[36]  A. Arenas,et al.  Community detection in complex networks using extremal optimization. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[37]  M. Newman,et al.  Finding community structure in networks using the eigenvectors of matrices. , 2006, Physical review. E, Statistical, nonlinear, and soft matter physics.

[38]  M. Newman,et al.  Robustness of community structure in networks. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[39]  Paolo Santella,et al.  A Comparison of the Director Networks of the Main Listed Companies in France, Germany, Italy, the United Kingdom, and the United States , 2009 .

[40]  Jean-Loup Guillaume,et al.  Fast unfolding of communities in large networks , 2008, 0803.0476.

[41]  Fabio Bertoni,et al.  The Small-World of Italian Finance: Ownership Interconnections and Board Interlocks Amongst Italian Listed Companies , 2006 .

[42]  H. Gintis,et al.  Social Capital and Community Governance , 2002 .

[43]  M. Newman,et al.  On the uniform generation of random graphs with prescribed degree sequences , 2003, cond-mat/0312028.

[44]  E. A. Leicht,et al.  Large-scale structure of time evolving citation networks , 2007, 0706.0015.

[45]  M. Barber.  Modularity and community detection in bipartite networks. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[46]  James D. Westphal,et al.  Cooperative or Controlling? The Effects of CEO-Board Relations and the Content of Interlocks on the Formation of Joint Ventures , 1999 .

[47]  S. Fortunato,et al.  Resolution limit in community detection , 2006, Proceedings of the National Academy of Sciences.

[48]  B. Kogut,et al.  The Small World of Germany and the Durability of National Networks , 2001, American Sociological Review.

[49]  Ulrik Brandes,et al.  On Modularity Clustering , 2008, IEEE Transactions on Knowledge and Data Engineering.

[50]  Santo Fortunato,et al.  Community detection in graphs , 2009, ArXiv.

[51]  R. Guimerà,et al.  Modularity from fluctuations in random graphs and complex networks. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[52]  G. Weisbuch,et al.  Decision making dynamics in corporate boards , 2002, cond-mat/0209590.

[53]  G. Caldarelli,et al.  On the rich-club effect in dense and weighted networks , 2008, 0807.0793.

[54]  Mara Faccio,et al.  Politically Connected Firms , 2004 .

[55]  M. Mizruchi.  What Do Interlocks Do? An Analysis, Critique, and Assessment of Research on Interlocking Directorates , 1996 .

[56]  M. Meilă.  Comparing clusterings---an information based distance , 2007 .