This document discusses corporate-level strategy and diversification. It defines corporate-level strategy as specifying actions to gain competitive advantage by selecting and managing different businesses. Diversification can occur at different levels from low to very high. Reasons for diversification include economies of scope, market power, financial economies, and external incentives like regulations. Firms can create value through related diversification using shared activities or transferred competencies, or unrelated diversification through efficient capital allocation or restructuring. However, overdiversification driven by managerial motives can reduce value. Low firm performance also provides an incentive to diversify.