SAN FRANCISCO (CBS SF) — Both Google and Facebook announced Wednesday steps they’ve taken to stop the spread of fake news.

In a blog post on Wednesday, Scott Spencer, Google’s director of product management – sustainable ads, wrote:

“From November to December 2016, we reviewed 550 sites that were suspected of misrepresenting content to users, including impersonating news organizations. We took action against 340 of them for violating our policies, both misrepresentation and other offenses, and nearly 200 publishers were kicked out of our network permanently.”

Spencer said that ads pretending to be credible news sources threatens users, Google’s partners and “sustainability of the open web.”

He said, “In 2016, we saw the rise of tabloid cloakers, a new type of scammer that tries to game our system by pretending to be news.”

In all, Google took down 1.7 billion ads that the company determined had violated their advertising policies in 2016. Spencer said that is more than double the amount of “bad ads” the company took down in 2015.

Google says “cloakers” tend to take advantage of timely topics — such as a government election — making their ads look like headlines on a news website.

“But when people click on that story about Ellen DeGeneres and aliens, they go to a site selling weight-loss products, not a news story,” Spencer explains.

CBS San Francisco requested a list of publishers that Google has banned from advertising on their platform for impersonating news organizations or otherwise misrepresenting content to users, but a Google spokesperson said, “We don’t disclose details related to individual sites in violation of our AdSense policies, it’s not unique to this case.”

Facebook has also announced that it is doubling down on its efforts to prevent fake news from appearing in its feed of trending topics.

In a blog post on Wednesday, Will Cathcart, Facebook’s vice president of product management, wrote that the trending topics feature now shows not only the publisher’s headline below a topic’s name but also the name of the publisher in order to give Facebook users more context before they click.

Cathcart writes, “Trending uses a variety of signals from News Feed, including when people report news as fake or spam, to help prevent fake news, hoaxes or spam from appearing in Trending. Today’s update may also help prevent hoaxes and fake news from appearing in Trending because the updated system identifies groups of articles shared on Facebook instead of relying solely on mentions of a topic.”

This, Cathcart maintains, should “help ensure that trending topics reflect real world events being covered by multiple news outlets.”

Facebook’s changes begin rolling out Wednesday and will be visible nationwide in the coming weeks.

By Hannah Albarazi – Follow her on Twitter: @hannahalbarazi.