Corporate portfolio management within Japanese diversified trading & investment companies : what role does real estate play?

Abstract

This paper discusses possible optimal corporate portfolio composition for Japanese trading and investment firms from stakeholders' (specifically shareholders and employees) value maximization perspective. Based on the historical returns of diversified business units of 4 subject companies, performances of individual business units and three portfolios (current, tangency, and "suboptimal") are analyzed and compared. The study suggests adjusting suboptimal portfolio composition based on each business unit's systematic risk and excess market return relative to its systematic risk and industry average. A firm also needs consideration on how the composition adjustment would affect diversification benefits the firm now enjoys and also on its overall management strategy. Key words: corporate portfolio management, diversification, stakeholder theory, portfolio theory, CAPM, Index model, accounting beta, Jensen's Alpha, Treynor ratio, multi-factor model.