Twitter shares fell sharply in extended trading Thursday after the company reported better-than-expected revenue and profit but missed estimates for user growth.

For the third quarter, Twitter’s revenue rose 14% year-over-year to $936 million while net income fell to $28.66 million, or 4 cents per share, from $36.5 million. Adjusted earnings came in at 19 cents per share.

Analysts had expected earnings of 6 cents per share on revenue of $777 million.

“Advertisers significantly increased their investment on Twitter in Q3, engaging our larger audience around the return of events [that had been paused by the coronavirus pandemic] as well as increased and previously delayed product launches,” CFO Ned Segal said in a news release.

Ad revenue in the third quarter grew 15% to $808 million from the same period a year ago, surpassing estimates of $645.95 million.

But Twitter shares dropped 17.5% to $43.24 in the after-hours session as total monetizable daily active users increased by just 1 million to 187 million, below analysts’ expectations of 195 million mDAUs.

Twitter added 20 million mDAUs in the second quarter but in an earnings call, executives suggested that reflected a spike in engagement levels during the early part of the pandemic.

Costs and expenses rose 13% to $880 million in the third quarter as Twitter spent more on infrastructure-related expenses.

The company said that in the last three weeks of Q3, ad revenue was up 19% year over year, “a significant improvement from the 15% year-over-year decrease we saw in the last three weeks of Q2, and potentially a good demonstration of how we can perform when so many events and product launches are driving people and advertisers to Twitter.”

Twitter indicated uncertainty about future growth, saying the upcoming U.S. presidential election makes it “hard to predict how advertiser behavior could change.” But it added that “we have no reason to believe that September’s revenue trends can’t continue, or even improve, outside of the election-related window.”