Facebook stock fell Friday, the day after Chief Product Officer Chris Cox announced he was leaving the company in light of its recent pivot to privacy.

Shares fell as much as 4.5 percent in early trading, sinking below $163 at its lowest point. The stock eased off by mid-morning and ended the day 2.5 percent down.

Insiders told CNBC that Cox was the "heart and soul" of Facebook. He was among the earlier employees and reported directly to CEO Mark Zuckerberg. His departure hangs uncertainty on Facebook's recent announcement to integrate its family of apps and prioritize private communication.

Separately Friday, Facebook drew criticism related to a terrorist incident in New Zealand in which a shooter live-streamed his attack on Facebook. The shootings claimed at least 49 lives.

The company was alerted to the post by New Zealand police and said it has been taking down re-postings of the video and messages praising the shooter as it becomes aware of them.

On top of that, Facebook suffered its longest outage ever this week. The service was reinstated Thursday after a widespread outage that last nearly a day.

In a statement Thursday, the company blamed a "server configuration change that triggered a cascading series of issues" for the outage.

The stock shed 1.8 percent by the end of trading Thursday.