If you don't find market share information in secondary sources such as databases and websites, you may calculate an estimated market share. Divide your company's sales (if your company has only one type of product) or your product's sales (if your company has multiple products) by industry revenue (available in the Economic Census) or industry profiles.
A Google search can return many links that seem to promise easily available market share information. Googling industry associations and browsing/searching on those sites can be helpful too. Here are two tips for effective googling:
When you do a Google search, make sure you retrieve only the most recent data (unless you are looking for historical information) by narrowing down the results to "past year" or a custom range. You can also add the year to the search, e.g., market share digital camera 2014.
Information might come from many different sources, such as newspapers, trade publications, industry associations, and even blogs, which are a great source of current information, esp. in the technology field. However, before you use the info, find out where the data come from. Responsible bloggers cite their sources. If there is no source, try another Google search to see if the information has been mentioned elsewhere. Be wary of numbers without a credible source.