https://www.theverge.com/2017/10/2/16405974/facebook-russian-election-ads-10-million-viewers

Facebook says that it displayed Russia’s divisive election ads to 10 million people, most of whom saw the ads after the election was over. It’s not clear how many impressions that equates to (it’s possible one person saw multiple ads), but Facebook says that 44 percent of the ads were displayed before the 2016 election, and 56 percent came after. Facebook says it’s identified more than 3,000 ads in total, stemming from a Kremlin-linked group known as the Internet Research Agency.

The details were released following Facebook’s disclosures to Congress earlier today. The company shared the 3,000-some ads with legislators and committed to hiring 1,000 more moderators to review ad placements in the future.