A planning model developed by Bruce Henderson of the Boston Consulting Group (BCG) in the 1970s. The model compares each business unit of a company against its main competitor in terms of market growth and market share. Business units are divided into four categories. "Dogs" have low market share and low market growth. They are candidates for divestiture. "Question marks" have high market growth but low market share. They should be watched carefully to see if their competitive position improves. "Stars" have high market growth and high market share. They generate large amounts of cash, but they also require large investments to maintain their growth. "Cash cows" have large market share in a mature market. They generate a large part of the company's income.