Brad Parscale, the Trump campaign's digital director, alleged that the Trump campaign had been able to push ads on Facebook with extremely low CPMs (cost per thousand impressions):

Clinton herself responded to this tweet regarding Parscale:

Clinton's tweet prompted a response from Facebook exec Andrew Bosworth (known to most as simply Boz):

• "Lots of confusion about ads pricing today. Remember, price for any given impression is determined by an auction so by definition this pricing cannot be discriminatory."
• "Two advertisers trying to reach different audiences will pay different amounts, but that’s the same with billboards or any other media (think times square vs rural Montana)"
• "If you are measuring “cost per outcome” then obviously the creative plays a huge role, but that’s not the same as measuring cost per impression for the same audience"
• "The only caveat is that our auction favors good creative which improves user experience. However that benefit is on the order of +/- 10%, meaningful for advertisers but far from 200x"