American Press Institute:

When Americans encounter news on social media, how much they trust the content is determined less by who creates the news than by who shares it, according to a new experimental study from the Media Insight Project, a collaboration between the American Press Institute and The Associated Press-NORC Center for Public Affairs Research.
 
 Whether readers trust the sharer, indeed, matters more than who produces the article —or even whether the article is produced by a real news organization or a fictional one, the study finds.