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Understand what market share can demonstrate about a business. Comprehend the limitations of the market share indicator. Think about how market share should shape your investment strategy.

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Market share is not an end-all tool that tells you everything you must know; quite the opposite, it is more of a tool of initial inquiry. You must understand both the strengths and limitations of it as an indicator of value.  Market share is a good tool to use to compare two or more similar companies that compete against each other in a market. Though not exactly a popularity contest, it does demonstrate the extent to which one firm's product out-competes (or fails to compete against) the rest of the field. Consequently, market share can indicate likelihood of a firm's growth. If a firm has claimed increasing market share for several consecutive quarters, they have clearly figured out how to manufacture or market an especially desirable product. Companies that are losing market share may be suffering from just the opposite. As noted above, market share is a limited tool that can help you develop an initial perception of a firm. Taken by itself, it means little.  Total revenues--the sole factor used to determine market share--provide little information about the profitability to a company. If one company holds a larger portion of the market but makes substantially smaller profit (revenue minus expenses) than another, market share becomes a substantially less significant indicator of current or future success. The market share may indicate more about the market than the company you are evaluating. Some markets have been consistently dominated by a single or small group of companies, and little perceivable change has taken place over the course of many years. The power of an entrenched monopoly can be almost impossible for other companies to break, and so an examination of market share will only demonstrate that fact. However, small firms may still successfully carve out a niche for themselves, and profitability is still possible. The extent to which a company is leading or struggling in its market should impact how you perceive it.  Companies that have not shown a growth in market share in years may not be worth investing in. Firms with a growing market share are worth keeping an eye on. Unless they are poorly managed and unprofitable (which you can also determine by examining all of the publicly released financial documents of a traded company), the value of the company is likely to the rise. Firms with declining market share may be struggling. It is not the only factor that must be examined to determine this, but the company should be avoided if they also have declining profits or no new product or service offerings forthcoming.