Donald Trump and Steve Bannon with a park ranger in Pennsylvania. AP Photo/ Evan Vucci A growing number of companies are pulling their ads off of Breitbart News, the far-right website that until recently was run by President-elect Donald Trump's chief strategist Steve Bannon.

On Tuesday, Kellogg's announced that it would no longer advertise on the website in an effort to "ensure our ads do not appear on sites that aren't aligned with our values as a company," the company said in a statement published in USA Today.

Breitbart News is a controversial website that Bannon began running 2012. The site is known for its aggressive pro-Trump coverage and has come under fire for publishing articles that appear sympathetic to white nationalists, a charge that Breitbart has denied.

Headlines on Breitbart News include “Hoist It High and Proud: The Confederate Flag Proclaims a Glorious Heritage” and “Birth Control Makes Women Unattractive and Crazy."

The Southern Poverty Law Center labeled the site a "white ethno-nationalist propaganda mill."

In pulling its ads, Kellogg's became the largest in a growing list of companies that are cutting ties with Breitbart News. Warby Parker, Allstate, Nest and SoFi have already pulled ads from the site. AppNexus, a service that runs digital ads, has also barred Breitbart News, according to Bloomberg.

Breitbart News has been the target of a social media movement aiming to cut off its ad dollars. In November, the Twitter account Sleeping Giants began encouraging followers to put pressure on companies whose ads appear on the site.

As a result, Twitter users have called out ads for a number of different companies and institutions, including Yale University, Microsoft, and American Express.

Because of the ad software Breitbart uses, many companies were apparently unaware that their ads had been running on the website. If brands using this software want to avoid running ads on certain websites, such as Brietbart, they need to specifically blacklist these sites.

On Wednesday, the website launched a campaign encouraging readers to not purchase Kellogg's products.