I develop a stationary real options model with corporate restructuring costs that endogenously generates a diversification discount. This result requires that restructuring costs associated with spin-offs (refocusing moves) be significantly larger than those associated with acquisitions (diversifying moves). The discount is due to the fact that diversified firms performing poorly will still delay refocusing, given the high cost of implementing this strategy. The model delivers the counter-intuitive implication that the higher the (average) discount observed in the economy, the higher the (average) proportion of diversified firms.

Existing literature emphasizes skills-based explanations for executive-firm matching, namely in the context of financial expertise. In contrast, our paper argues that informational concerns may also be relevant. We model a public firm with a project opportunity of uncertain quality, where long-run shareholders choose between hiring an operational manager or a financial expert. These managers are equally myopic, however financial experts are also privy to stock-market beliefs. Financial experts invest sub-optimally due to catering incentives, while operational managers tend to engage in signaling-driven overinvestment. We show that operational managers are preferred for low-NPV projects or when stock markets are well informed.

We document a strong decline in corporate-diversification activity since the late 1970s, and we develop a dynamic model that explains this pattern, both qualitatively and quantitatively. The key feature of the model is that synergies endogenously decline with technological specialization, leading to fewer diversified firms in equilibrium. The model further predicts that segments inside a conglomerate should become more related over time, which is consistent with the data. Finally, the calibrated model also matches other empirical magnitudes well: output growth rate, market-to-book ratios, diversification discount, frequency and returns of diversifying mergers, and frequency of refocusing activity.