Market Share Market share is considered an important indication of competitive strength. It is expressed as the percentage of total sales of a given market held by each competitor. An important consideration is how broadly or narrowly the particular market is defined. The significance of a company's market share depends entirely on the market being measured. Finding information on market share can sometimes be difficult.
Trade journals are often the best source to check.
Use the periodical indexes to look for relevant data. Then, scan standard industry sources. A few specialized sources are listed here. They are costly, therefore most libraries cannot afford to collect them. Many of these market research firms are creating a presence on the Web.