Twitter reported quarterly earnings that met analysts' expectations on Monday, but the stock abruptly fell in after-hours trading after the company issued guidance that disappointed investors.

The company posted third-quarter earnings per share of 1 cent, which matched expectations, according to a consensus estimate from Thomson Reuters. Revenue for the quarter came in at $361 million, beating estimates of $351 million. Twitter posted a revenue of $169 million in the same quarter last year.

Twitter CEO Dick Costolo at the NYSE for the Twitter IPO launch. Adam Jeffery | CNBC

The tech firm's fourth quarter guidance is in the range of $440 to $450 million. Analyst estimates for that quarter averaged $448 million. Twitter stock fell over 10 percent in after-hours trading. "This wasn't a disastrous quarter. It's just that valuation gets in the way," said Guy Adami, "Fast Money" trader. The company also announced that it had grown by 13 million monthly active users to 284 million—a 23 percent year-over-year increase. This metric is "priority number one," Twitter CEO Dick Costolo told CNBC after the announcement. "We have an aspirational goal to build the largest daily audience in the world," he said, adding that this group also includes "hundreds of millions" of users who never log into the platform. Read More 140 things you don't know about Twitter Costolo said the company is seeking to "deploy experiences that are super valuable and engaging to that logged out audience no matter how they come to the platform." One figure that actually declined for Twitter was its timeline views per monthly active user—falling from 793 to 774 in the United States since the prior quarter. This was the second straight quarter that engagement metric fell. This decline was expected, as "the year-over-year decline primarily reflects the changes we've been making to allow users to more efficiently access our content," Twitter CFO Anthony Noto said on the call following the announcement. Still, Noto said this metric remains Twitter's primary measurement for engagement. Internal analysis shows that newer users are viewing their timelines less than longer-term members, he said, but this group eventually ramps up average use after some time on the platform.