The market is abuzz as Twitter (TWTR) released its fiscal fourth-quarter results after the bell today. The social media giant delivered better-than-expected revenue of $243 million in the quarter, which was a year-over-year increase of 116%. For comparison, analysts were looking for revenue of revenue of $218 million in the period. Twitter also beat profit estimates with earnings-per-share of $0.02 in the quarter, ahead of Wall Street's estimate of a $0.02 loss.

This was an important quarter for the social-media business, because it was Twitter's first earnings report since its initial public offering in November. However, despite what would otherwise be a blowout quarter, investors pushed shares of Twitter lower in after hours trading on concerns that the social-media company's growth is slowing.

For the quarter ended in December, Twitter counted 241 million average monthly users. However, that's up from just 230 million average monthly users in the previous quarter. As a social media company, investors are looking for growth, and Twitter just wasn't able to deliver.

The social-media giant has been on a winning streak since going public late last year. Shares of Twitter surged 73% in their stock market debut, climbing in value from $26 a share to more than $66 a share. However, they're taking back some of those gains today with shares falling more than 16% to trade around $55 as of 5:53 p.m. ET.