Facebook's free pages are often used by companies to reach them for free. Facebook says they will appear much less often, and marketers will have to buy ads to remain visible. Reuters

Facebook is going to cut down on the promotional posts in your news feed. From now on, if companies want to show up on the social network, they will have to buy ads.

Facebook Inc. told marketers on Friday that the change was to improve its user experience, and followed a number of complaints. Facebook ranks posts using software to determine which will appear in users’ news feeds. It said it will change the ranking in January for Facebook “Pages,” the free profiles for companies that users of the service have “liked.”

“Most of the stuff we listed, like sweepstakes, probably doesn’t fall in the category of great content,” Facebook’s vice president and head of ads, Brian Boland told the New York Times. “We’re responding to what people want to see.”

Facebook ads are selectively shown to users based on factors like their interests, location and age, and Boland told the Times that they were a better way for companies to reach users. Posts that are engaging or creative will still garner attention on Facebook, he said.

Facebook says it has to filter through 1,500 potential posts to fill most users’ news feeds, of which the average user only sees about 300. While Facebook has adjusted the site so that companies’ posts show up less frequently, it says a more drastic change is necessary, since its users prefer photos, news articles and status updates from friends and family to brand messages.

Facebook’s stock rose following a report about its third quarter, where advertising revenue rose 64 percent to $2.96 billion, with ad prices nearly tripling due to high demand. But investors grew nervous recently, after the company said it planned to spend large amounts of money on products that may never yield profits, much like fellow tech titan Google Inc.