I don't think facebook shares much data to other companies, they have more to gain by keeping it to themselves and having all the data to serve their billions of users personnalized ads. Basically the same as Google, they don't really sell your data. For these companies I never really liked the phrase that says you are the product, youre not really the product, you are what makes their product. If a company sold your data plainly, then yes in thsi case you are the product