Final answer:
The sale of a firm's SBU to a competitor is an acquisition. This business strategy allows companies to grow or enter new markets, and is protected but also regulated by antitrust laws to prevent anti-competitive outcomes.
Step-by-step explanation:
The sale of one of a firm's Strategic Business Units (SBUs) to a competitor, where that SBU continues to operate, is referred to as an acquisition. When one firm purchases another, the bought firm generally keeps operating under the new ownership, either as a part of the acquiring firm's portfolio or as a standalone entity within the larger corporate umbrella. This is a strategic move usually made for several reasons, such as entering a new market, acquiring new technology, or eliminating competition. In a market-oriented economy, companies engage in such transactions to achieve growth and to adapt to competitive environments.
Sometimes, however, antitrust laws may come into play. These laws are designed to ensure active competition in the markets and can prevent certain mergers and acquisitions if they are deemed to significantly reduce competition. They may even result in the government having the power to break up large firms into smaller competitors in order to maintain a healthy competitive landscape.