Facebook ad revenue tops $10bn
Facebook profits soared in the third quarter as it brought in more than $10bn from advertising.
The firm said profits were $4.7bn (£3.5bn) in the three months to the end of September, up 80% year-on-year.
Chief executive Mark Zuckerberg told investors the firm's investments in security would "impact" profitability.
US lawmakers are examining the possible use of the platform for Russian propaganda activities during the 2016 US presidential election.
"We're serious about preventing abuse on our platforms," Mr Zuckerberg said. "Protecting our community is more important than maximising our profits."
Mr Zuckerberg last year said the idea that fake news on Facebook influenced the election was "pretty crazy".
On Wednesday, the firm said almost 150 million people may have seen Russian propaganda efforts.
Facebook shared the figure during two days of tense questioning in Washington.
Lawmakers, who are eyeing increased regulation of internet companies, pressed for increased disclosure around political ads, as well as information about how the firm polices false content.
Mr Zuckerberg did not attend the hearing, but he discussed the matter on a conference call with financial analysts.
"What [Russia] did is wrong and we are not going to stand for it," he said.
"People do not want false news or hate speech or bullying... To the extent that we can eradicate that from the platform, we will create a better product."
The firm's general counsel told lawmakers the company was focused on protecting the "authenticity" of activity. But he conceded that it would be a tough task.
Facebook had 2.07bn monthly active users at the end of September, up 16% year-on-year.
Duplicate accounts represent about 10% of those - higher than previous estimates, executives said.
It also had more than six million active advertisers, chief operating officer Sheryl Sandberg said on a call with investors.
Those advertisers, many of them small and medium-sized businesses, helped lift total Facebook revenue 47% year-on-year to $10.3bn. That included $10.1bn from ads.
The firm said it expected ad prices to increase, driving future growth. But it warned that the pace of expansion had been slowing.
The firm also said it expected expenses to increase between 45% and 60% in 2018.
Facebook said it was investing in security initiatives, new technology and video.
In the Washington hearings, Facebook said 10,000 people were working on the platform's safety and security and it expected that number to double by the end of 2018.
Many of those people work for "partners", the firm told analysts. Facebook employed about 23,165 people at the end of September.
The firm said it was also tightening it standards for ads, including those focused on charged political issues.
"We believe that ads are important to free expression... but we will also do our part to elevate the quality of that discourse," Ms Sandberg said,
Shares in the firm fell about 1.5% in after-hours trade.