What: It's been a tough ride for Qlik Technologies (QLIK) investors this year -- and the stock's decline just worsened. Shares slid as much as 19% on Friday following the company's fourth-quarter results. The stock is down about 12% at the time of this writing and 46% year-to-date.

So what: Fourth-quarter results and first-quarter guidance below analysts' expectations were likely reasons for the stock's sell-off on Friday. The company reported revenue and non-GAAP EPS of $205.5 million and $0.31, respectively. Analysts were expecting revenue and non-GAAP EPS of about $208.2 million and $0.38, respectively.

Qlik guided for first-quarter revenue and non-GAAP EPS of $132 million to $136 million and a loss of $0.12 to $0.14, respectively, while analysts were expecting about $140.6 million and a loss of $0.08 per share.

Now what: Qlik's management is optimistic about the company's business, even noting in its fourth-quarter press release that the company actually exceeded its fourth-quarter revenue guidance on constant currency and still managed to slightly improve its non-GAAP operating margins. Going forward, the company expects more of the same. Management is predicting its operating margin will continue to improve throughout 2016 and that its revenue growth will actually accelerate from 10% in 2015 to a range of 13% to 15% during 2016.