Facebook is updating its ad viewability and reporting policy. The company's service will let advertisers pay for ads only when they are scrolled through from top to bottom on its news feed. In addition, Facebook is ntroducing a new partnership with ad analytics company, Moat, which will independently measure Facebook video ads.

Facebook believes in measuring ad delivery with viewed impressions, rather than served impressions. So to give advertisers more choice and control, the company is introducing a new buying option that allows advertisers to purchase 100% in-view impressions on Facebook.
100% in-view impression buying gives advertisers the option to purchase ad impressions where the entire ad-from top to bottom-has passed through a person?s screen in News Feed.

The new service will include text, photo, link and video ads, the company said in a blog post on Thursday.

Facebook also said it was partnering with Moat, an ad analytics company, which would verify video ad metrics on Facebook.com to give advertisers details on the performance of their video campaigns.

The company said Moat would later extend its services to all other ads on news feed, including the service launched today, and also to ads on Facebook's photo-sharing app, Instagram.

In July, Facebook reported better-than-expected second-quarter revenue but profit fell 9 percent as the social media company sharply increased spending to boost mobile revenue and future growth.

Facebook, which bought Instagram in 2012 for $1 billion, dominates mobile advertising, with more than 75 percent of its $3.8 billion ad revenue coming from phones.