Markets dislike uncertainty. That certainly holds when it's introduced to the outlook for a company whose shares have risen over 400% since mid-2013.

Thus the uncertainty created by earnings call remarks from Facebook  (FB) CFO Dave Wehner about his company's 2017 performance led shares to drop 7% in after-hours trading on Wednesday, and open with a 4.7% decline on Thursday. But there are good reasons to avoid panicking.

Facebook was nearly unchanged going into its Wednesday call, after having beaten third-quarter estimates against a backdrop of high expectations. Adjusted EPS of $1.09 (up 91% annually) topped a $0.97 consensus with the help of slower spending growth -- total expenses rose 28%, down from Q2's 33% clip -- and a relatively low 25% tax rate. Revenue of $7.01 billion (up 56%) topped a $6.92 billion consensus thanks to a 59% increase in ad revenue to $6.82 billion.

But shares quickly went south after Wehner forecast Facebook's ad sales growth will "come down meaningfully" next year, as increases in the frequency at which ads are shown on Facebook's news feed (ad load) become "a less significant factor driving revenue growth after mid-2017." The ad load remarks are similar to ones made on Facebook's Q2 call.

Wehner also said 2017 would be "an aggressive investment year," with Facebook spending heavily on both talent and (due to its data center buildout) capital expenditures. This will follow a 2016 in which adjusted costs and expenses are expected to grow 40% to 45% (down slightly from a prior forecast of 45% to 50% growth).

Facebook is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells FB? Learn more now.

If you liked this article you might like

North Korea's Nuclear Threat Pressures Wall Street at Trading Week's End

LA Times Tops 100,000 in Digital Subscriptions

Stocks Claw Back From Session Lows as Markets Digest North Korea Threat

North Korea Threat Resurfaces to Drag Stock Futures Lower

7 Essential Rules for Investing in Tech Stocks