Facebook posted strong results for Q3 with a 49% increase in ad revenue from the same period last year. But it warned that profits are likely to slow next year as it invests in measures to fight fake news on its platform.

The social media giant’s ad revenue reached $10.14 billion for the period ended Sept. 31 (all figures in U.S. dollars), up from the $9.1 billion reported in Q2 of this year. Overall, the company brought in $10.33 billion in revenue, surpassing the $10 billion mark for the first time.

Mobile advertising grew as a percentage of total revenue, representing about 88%, up from the 84% reported over the same period in 2016.

In a conference call, Facebook executives said there are now more than 6 million businesses paying for advertising on Facebook, and the average price of the ads have increased by 35% year-over-year. Its Instagram platform now has 2 million advertisers on its service.

However, Facebook’s overall revenue growth slowed for the fifth consecutive quarter.

In a conference call, Facebook CFO Dave Wehner said that the company’s revenue growth would continue to slow as it approaches the limit of ads that can be shown in its news feed. He said that future growth will be based on the price of ads.

Facebook’s daily active and monthly active users both grew 16% from the same period last year, reaching 1.37 billion daily and 2.07 billion monthly users.

The cost of security
The company’s profits will also be impacted by measures the company is taking to deal with the spread of fake news and misinformation.

In a statement, Facebook founder and CEO Mark Zuckerberg said the company is serious about preventing abuse on its platform. “Protecting our community is more important than maximizing our profits,” he said.

Earlier this week, the company told U.S. lawmakers that it plans to double its roughly 10,000 employees working on safety and security issues by the end of 2018.