Database of public and private companies. Use it to find basic info as well as a corporate tree (who owns whom). Search by brand name to find the owner of that brand. Great place to find competitor information.
Industry Reports: Many include information on market share. Some of their industry reports may include more niche industry info than IBISWorld Trade Articles: Search for trade articles relating to market share in your industry. So a search for your product and "market share."
How to Locate U.S. Industry Reports
Locating industry reports in Business Source Complete and IBISWorld.
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