The thesis is an empirical study of the changes that occurred in the Fortune list of the largest American industrial corporations from 1963 to 1987. The mobility and turnover of big firms has been studied only from a neoclassical perspective in the past, and the emphasis was placed on the level of overall concentration in the economy. In this thesis, the changes in the list are analysed adopting a Schumpeterian/evolutionary framework that emphasize the importance of innovation and economic change as major determinants of economic progress. Recent evolutionary models that describe the evolution of industries. and the work of economic historians such as Alfred Chandler provide a framework for the empirical analysis. The main findings.are: I. The takeover activity is the main source of turbulence in the list. 2. There are significant inter-industry differences in the type of competition and in the behaviour of the industries. and these differences shed light on the overall changes. 3. The emergence of microelectronics has powerful destabilising effects, and its diffusion interacts with other trends such as the growing globalisation of competition between large firms and the rise of the market for corporate control.