What: Shares of ServiceNow (NYSE:NOW) fell 19% early Thursday after the cloud-based enterprise software company reported better-than-expected fourth-quarter 2015 results but followed with disappointing guidance.

So what: Quarterly revenue rose 44% year over year (51% at constant currency) to $285.7 million, including a 46.7% increase in subscription revenue to $244.7 million and a 31% increase in professional services and "other" revenue to $41 million.

Based on generally accepted accounting principles, which translated to a net loss of $37.4 million, or $0.23 per share, narrowed from a GAAP net loss of $0.30 per share in the same year-ago period. On an adjusted basis, which means excluding items like stock-based compensation, ServiceNow reported net income of $32.6 million, or $0.19 per diluted share, up from non-GAAP net income of $4.9 million, or $0.03 per share in last year's fourth quarter.

Analysts, on average, were modeling adjusted earnings of $0.08 per share on lower revenue of $281.4 million.

ServiceNow's billings rose 33% year over year to (39% at constant currency) to $365.7 million, and the company generated healthy free cash flow of $80.2 million, up 107% year over year.

CEO Frank Slootman added, "We marked a huge milestone in 2015, becoming only the second enterprise SaaS company to surpass $1 billion in revenue. This was our largest quarter yet for net new annualized contract value, punctuated by 26 net new Global 2000 customers in the quarter."

Now what: For the current quarter, ServiceNow anticipates revenue between $298 million and $303 million, including subscription revenue between $261 million and $265 million, and professional services and other revenue between $37 million and $38 million. Overall, that's good for year-over-year growth between 41% and 43% (or between 42% and 44% at constant currency) and above analysts' expectations for revenue of $297.8 million.

However, the market was much less impressed with ServiceNow's full-year outlook, which calls for total billings of $1.6 billion, good for year-over-year growth of 33% to 34% at constant currency. ServiceNow also expects 2016 revenue between $1.34 billion and $1.37 billion, up between 33% and 36% from 2015 as reported and between 34% and 37% at constant currency. That includes subscription revenue between $1.18 billion and $1.20 billion and professional services and other revenue between $160 million and $170 million.

By contrast, analysts' consensus estimates called for full-year revenue near the high end of that range, and it appears Wall Street is concerned that the more modest growth in billings could be a harbinger of greater deceleration in ServiceNow's top-line growth.

At the same time, it's not as though ServiceNow's full-year revenue and billings guidance were overwhelmingly negative. The company is still growing nicely and all the while anticipates demonstrating healthy operating margin and free cash flow margin of 12% and 24%, respectively. But with shares still trading above 60 times next year's estimated non-GAAP earnings, 13 times trailing-12-month sales, and ServiceNow still unprofitable on a GAAP basis, it's no surprise the market is bidding down ServiceNow stock at the first sign of imperfection.

Steve Symington has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.