This study analyses whether the effect of corporate diversification on a firm's market value depends on how this strategy is implemented. According to the real options approach, two opposite diversification strategies may be implemented: one based on fully exercising available options (assets-in-place diversification) and the other aimed at seeding new opportunities for future growth in multiple businesses (growth options diversification). We propose an index to measure these two diversification patterns and we explore their impact on firm market value for a sample of U.S. firms during 1998–2014. We find that as a firm's diversification strategy shifts towards a growth options pattern, it becomes a more value-enhancing strategy.