Twitter on Thursday reported fourth-quarter earnings and revenue that beat estimates, but the stock slid 9.8 percent Thursday after the company provided light guidance and said it expected expenses will increase 20 percent this year. Monthly active users data met analyst expectations, but the company said it's changing the way it reports active users on the service.

Here's what Twitter reported:

Earnings per share: adjusted 31 cents vs. 25 cents expected in a Refinitiv survey of analysts

Revenue: $909 million vs. $868.1 million expected in the survey

Monthly active users (MAUs), excluding SMS users: 321 million vs. 321 million expected in a FactSet consensus

Twitter's outlook for Q1 2019 revenue fell within analyst expectations, anticipating $715 million to $775 million compared with analyst estimates of $764.9 million, according to Refinitiv consensus estimates. Twitter said it expects its cash operating expenses to increase about 20 percent year over year in 2019 to bolster its initiatives across "health, conversation, revenue product and sales, and platform."

Investors will likely be scrutinizing Twitter's monthly active users growth. While the company roughly met analyst estimates for MAUs this quarter at 321 million, the metric was down from last year's 330 million MAUs, likely due to recent initiatives that prioritize user well-being over engagement.

Twitter said Thursday it will stop reporting MAUs after the first quarter because it will switch to a new metric, monetizable daily active users (mDAUs) to reflect its audience.

Twitter fell short of MAU estimates for the two previous quarters. The company blamed a July purge of "locked" accounts aimed at getting rid of bots and fake users as well as "a number of factors including: GDPR, decisions we have made to prioritize the health of the platform and not move to paid SMS carrier relationships in certain markets, as well as a product change that reduced automated usage and a technical issue that temporarily reduced the number of notifications sent."

Twitter noted it is now reporting mDAUs rather than daily active users. The company said mDAUs measures "Twitter users who log in and access Twitter on any given day through Twitter.com or our Twitter applications that are able to show ads."

Twitter said its mDAUs are not comparable to disclosures from other companies because its peers tend to share "a more expansive metric that includes people who are not seeing ads." The company said it will now report average mDAUs for both U.S. and international markets.

Twitter reported mDAUs of 126 million for the quarter compared with 115 million a year earlier. It said average U.S. mDAUs were 27 million for the quarter compared with 25 million in Q4 2017, while average international mDAUs were 99 million for the quarter versus 89 million a year earlier.

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Still, Twitter has posted eight-straight quarters of growth in daily active users, reporting a 9 percent increase in the third quarter of 2018. Chief Financial Officer Ned Segal told CNBC last quarter he sees room for further growth in that metric since less than half of MAUs access the site daily.

CEO Jack Dorsey has hinted at new features that would aim to prioritize users' well-being over engagement with the platform. On a call with analysts following the Q4 results, Dorsey said the company is thinking about ways to make conversations on Twitter, which he says as its core differentiation, easier to follow. He said Twitter has already seen progress with the recent release of a feature that lets users switch between a "ranked" timeline based on what Twitter thinks is most relevant to users and a reverse chronological timeline.

"The timeline switch that we released not too long ago, we weren't expecting to see an increase in replies and conversations but in fact it did that exactly," Dorsey said, adding that they will continue to steer the service toward serving people content related to their interests, which will in turn help advertisers better reach their target audiences. "And what this means is being able to much easier follow an interest, express an interest from on-boarding when you first download an app … all the way to local news events to emergency situations or anything that's breaking within your particular market or around the world. Or long-term interests that you might have that you have to dig a lot through Twitter to find the relevant accounts. We think we can make this much much easier. And we think this is what Twitter wants to be."

In an interview with Rolling Stone published last month, Dorsey said his team has been "thinking about what happens if we remove the 'like' counts" from tweets.

"Ultimately, I want every single person that uses Twitter to not spend hours, or days, or minutes consuming content, but [instead] to be notified when there's something that potentially they could learn from, and, to the highest degree, that they'd want to participate in a conversation around it," Dorsey told Rolling Stone.

Twitter, along with social media peers including Facebook, has faced headwinds in the past year over its role in spreading misinformation and contributing to "filter bubbles." Dorsey testified in front of the Senate Intelligence Committee in September alongside Facebook COO Sheryl Sandberg over foreign meddling during the 2016 U.S. election.

Twitter has since taken steps to reduce the spread of misinformation of its platform, including the bot purge and the removal of thousands of accounts it believed originated in Iran, Russia and Venezuela for the purpose of spreading misinformation around the 2018 U.S. midterm election.

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