Social-networking site Reddit posted better-than-expected fourth-quarter results, but its user growth missed forecasts. For the fourth quarter ended Dec. 31, Reddit said total revenue jumped 71% to $427.

Reddit stock is down Thursday after the social media platform fell short of expectations on a key metric for its fourth quarter. Here's what you need to know.

Reddit shares tumbled after the social-media company reported slower-than-expected growth in users. Daily users totaled 101.7 million for the three months through December—an increase from the previous quarter but less than the 103.

Reddit Inc. turned its second quarterly profit since becoming a public company, but shares fell after daily active unique users — which topped 100 million for the first time — fell short of expectations.