Anderson Cooper put a big dent in the Fox News ratings, but it's not how you think. 

The CNN Anchor was a guest on FNC's 'The Kelly File' and the ratings were awful. According to Nielsen, Coop's appearance with Megyn Kelly on Thursday was one of her lowest rated shows for the year. 

If you take out Friday nights and just use Mon-Thurs, Cooper's appearance brought Kelly's show her lowest demos for the year.  In fact, the show was down 36% from same day last week.  
Both hours before and after The Kelly File garnered higher ratings in the demo Kelly's show pulled 300k). The O’Reilly Factor averaged 433K and Hannity ranked had 328K. 

CNN boss Jeff Zucker had always hoped that Anderson Cooper would have an impact on FNC's ratings and it looks like he finally figured out how to make that happen.