For corporate management, deciding whether to run a multi-business firm or focus on a core business is crucial. The impact of corporate diversification on value has long intrigued researchers and practitioners. The author offers a thorough overview of recent research on how corporate diversification affects firm value, providing key insights for valuation. Traditional valuation models often struggle to account for the complexities of multi-business firms, which operate across various industries and exhibit unique growth potential, cash flow dynamics, and risk exposures. The author introduces a multi-business firm valuation approach that integrates the effects of corporate diversification on firm value. This method involves projecting distinct characteristics for each business segment and considers segment-specific cash flows and capital costs, reflecting varying risk and growth profiles. Additionally, the model addresses diversification effects throughout different business cycle phases, highlighting asymmetric co-movements between businesses, as demonstrated in an empirical study. These effects encompass cross-subsidization among segments, risk reduction via debt co-insurance, and implications for bankruptcy costs. The findings are valuable for strategic business planning and inform decisions regarding mergers, acquisitions, and private equity investments, particularly in optimizing diversification strategies within business
