The trending news section is run by people in their 20s and early 30s, most of whom graduated from Ivy League and private East Coast schools like Columbia University and NYU. They’ve previously worked at outlets like the New York Daily News, Bloomberg, MSNBC, and the Guardian. Some former curators have left Facebook for jobs at organizations including the New Yorker, Mashable, and Sky Sports.
According to former team members interviewed by Gizmodo, this small group has the power to choose what stories make it onto the trending bar and, more importantly, what news sites each topic links out to. “We choose what’s trending,” said one. “There was no real standard for measuring what qualified as news and what didn’t. It was up to the news curator to decide.”

Source: Want to Know What Facebook Really Thinks of Journalists? Here’s What Happened When It Hired Some.

The curators black listed some news topics.

News curators also have the power to “deactivate” (or blacklist) a trending topic—a power that those we spoke to exercised on a daily basis. A topic was often blacklisted if it didn’t have at least three traditional news sources covering it, but otherwise the protocol was murky—meaning a curator could ostensibly blacklist a topic without a particularly good reason for doing so.

Effectively, Facebook is running an ill defined propaganda operation that has the power to strongly influence public understanding, thought and to take actions. It was recently revealed that employees submitted questions to Facebook’s Zuckerberg, asking what steps they might take to influence the 2016 Presidential election.