1. Go to a fake news site (i.e. breitbart)
2. Click a few links and pause until an ad pops up
3. Create a screen capture
4. Find contact information on the company via their website or on Facebook
5. Email or Facebook message the company with the following
I am writing to alert you that your company's ads are on Breitbart, a white supremacist fake news site. I have attached a screenshot for your review. For now I will assume that your company is not aware that you are supporting this racist and misogynist platform and just hired an ad network service to place ads for you based on demographics. Companies can set a list of platforms that they refuse to be advertised in so I am writing to encourage you to do so. I hope you will respond in the affirmative within a week. thank you for your attention, [your name]
6. If you don't get any results you might try a followup with something like, "If I do not hear back from you I will make this broadly known via social media."
7. Some followup tips if the company is confused.
Companies have to individually blacklist platforms that they don't want to advertise on. I understand that corporations are quite savvy about porn sites but still learning about fake news sites. If you are using adwords this link shows you step by step instructions on how to [Exclude Websites from AdWords Campaigns] https://docs.google.com/document/u/1/d/1bwS7LdG3tt0TCSfzFgwZb0YW0JPK0fZ2dbbh2l7P3dY/mobilebasic