In its first quarterly earnings statement since the company’s initial public offering last year, Twitter is definitely not soaring.

Twitter reported a net loss of over $511 million in the fourth quarter of 2013 and ended the year with a total net loss of over $645 million. However, the company more than doubled its revenue in 2013 when compared to the previous year, reaching $664 million.

In after-hours trading, its stock price has fallen over 16 percent as of this writing.

“Twitter finished a great year with our strongest financial quarter to date,” said Dick Costolo, CEO of Twitter, in a statement. “We are the only platform that is public, real-time, conversational, and widely distributed, and I’m excited by the number of initiatives we have underway to further build upon the Twitter experience.”

There are now more Twitter users than ever before—the company reported a quarterly increase in users of 30 percent year-over-year, reaching 241 million by the end of the quarter.

The San Francisco startup attributed the loss to “$521 million of stock-based compensation expense, of which $406 million was for restricted stock units previously granted to employees, for which no expense had been recognized, until the effective date of our initial public offering in accordance with [Generally Agreed Accounting Principles].”