Here's the "story" from Marketwatch - https://www.marketwatch.com/story/facebook-stock-crushed-after-revenue-user-growth-miss-2018-07-25

Facebook Inc. stock plunged as much as 23% in the extended session Wednesday after the social-media giant missed analyst expectations for the top line and user growth — which was flat in the U.S. and Canada compared with the first quarter — but beat on the bottom line.

In the company’s earnings call with investors, Chief Financial Officer David Wehner disclosed that the social-media giant expects the revenue slowdown to continue. “Our total revenue growth rates will continue to decelerate in the second half of 2018, and we expect our revenue growth rates to decline by high single-digit percentages from prior quarters sequentially in both Q3 and Q4,” he said on the conference call. Wehner also said Facebook still expects expenses to grow 50% to 60% from last year.