Corporate networks typically arise in a country when a business elite consisting of bankers, politicians and/or members of a limited number of wealthy families hold multiple positions on the board of directors of important firms. While such networks first came to the attention of legislators and researchers at the turn of the 20^th century (e.g., Hilferding, 1910; Brandeis, 1914), today many firms still appoint bankers, politicians, managers and directors from other firms on their board (e.g. Booth and Deli, 1999; Agarwal and Elston, 2001; Byrd and Mizruchi, 2005; Faccio, 2006; Dittman et al., 2010). The literature lists three main arguments for the emergence and persistence of personal network structures: first, their efficiency for connected firms; second, path-dependent corporate structure choices and structural embeddedness; third, elite control, entrenchment, and interest protection. The main downsides of economies relying on personal network structures include conflicts of interests, anticompetitive behavior, lock-in and economic stagnation.

This PhD thesis investigates what triggered the formation of corporate network structures in Belgium, how they evolved from the mid 19^th and throughout the 20^th century and what value they had for connected firms and for the economy at large. To gauge long-term changes in the contribution of personal network structures to the Belgian economy, it charts the evolution of these networks from the mid-19^th century to the end of the 20^th. The empirical part of the thesis combines data on the composition of the board of directors of Belgian listed companies (multiple directorships, board seats held by politicians, nobles and bankers) with firm-level performance indicators (growth opportunities, survival probability and risk indicators). Using this data, we plot the emergence of business elite network structures, the position of particular companies in them, and we try to assess the probable advantages derived from them. Taking a long-term perspective (going as far back as 1858 and up to 1990), we also examine the question of why personal network structures persisted as corporate governance mechanisms while their economic contribution declined.