The researchers tracked the 100 most widely shared false news stories between Jan. 1 and Oct. 1 this year. The stories they tracked had all been fact-checked and debunked by Facebook's third-party fact-checking partners, which include The Associated Press.
The group found that, collectively, the fake stories were posted more than 2.3 million times and had an estimated 158.9 million views, along with 8.9 million likes, comments and shares. The false stories targeted both political parties, though Avaaz says the majority were against Democrats and liberals. Most of the false news sources were individual users' or non-official political pages.
Avaaz, a left-leaning online advocacy group, said stories it found spreading even after they were debunked. That included one falsely claiming that President Donald Trump's grandfather was a pimp and a tax evader and that his father was a member of the Ku Klux Klan. That story had an estimated 29 million views. Another story falsely claiming that Democratic Rep. Ilhan Omar attended an al-Qaeda training camp had an estimated 770,000 views.
In response to the report, Facebook said it has taken steps to reduce the amount of false news items posted and shared on its service, including more prominent warning labels on the content.
"Multiple independent studies have found that we've cut the amount of fake news on Facebook by more than half since the 2016 election," the company said.
Avaaz said in the report that the findings are the "tip of the iceberg of disinformation" ahead of the 2020 elections.