What is Market Share?

Market share is one of the first metrics consultants examine when assessing a company's competitive position. It can be measured in revenue terms (value share) or volume terms (unit share)—the distinction matters because a premium player might have high value share but low volume share, and vice versa.

Market share trends over time tell a powerful story. Gaining share indicates improving competitiveness, while losing share signals strategic or operational problems. However, the definition of the "market" matters enormously. A company might have 50% share of "premium organic yogurt" but only 5% of "all yogurt"—the framing changes the strategic implications entirely.

In case interviews, market share data often appears in exhibits. Look for relative share (your share vs. the largest competitor's share) as well as absolute share. A company with 30% share in a fragmented market of 20 competitors is in a very different position than one with 30% share against a competitor with 40%. BCG Matrix analysis uses relative market share as a key dimension.