Industry profiles often note "market share" of companies (sometimes products too). Note what is being covered -- the geography (U.S.? North America?). If it's a common product sold in supermarkets, is the data from supermarkets - or any place the product is sold? The market share has many definitions; these sources can provide some data for your research:
How significant is your target company in its industry? The following 2 sources are best bets to start.
Further, news about your company, in periodical articles and newspapers, may note the market share too. Yet, the phrasing might be different.
check key Company News page for the top recommended online resources.
How does your target company compare to others? While a company or industry profile often has brief information, consider also checking the key sources listed below.
Create customized lists of potential target companies with these online resources: