Resumen de Diversification des grandes entreprises et concentration de l'industrie en France
The study is based on the analysis of a table presenting as many lines as there are large firms and as many columns as there are industrial products (« level 600 »; classification with four digit classes). A breakdown of the firms' sales by product may be read along the lines. The table allows a simultaneous study of the diversification of large firms (along the lines) and the concentration of branches (in the columns). By grouping firms according to their main activity a sector-branch table may be derived in which sales pertaining to main activity, sales to connected branches and sales in more distant fields appear separately. Furthermore, this table reveals the structure of inter-activity relations. We propose and apply a method to split up sales into three multiplicative factors : the degree of diversification, the average market share, the average market size. The degree of diversification is in turn analysed in consideration of three « levels » of the classification, and, within groups, by taking into account inter-firm and intra-firm diversification components.
