As many companies evolve, they see potential for growth or improved operations by combining their efforts with other businesses. In some instances, seizing these opportunities invokes a legal requirement to spin off some productive assets. Mergers, acquisitions, and divestitures all involve a structural change to an underlying business form of at least one company through the purchase or sale of an entire company or its parts. These procedures may occur with the acquiescence of both parties, or may involve the absorption of an unwilling business. In either case, federal laws govern transactions that affect public shareholders' interests.