Chris Cox: longtime Facebook executive exits as network focuses on privacy

Chief product officer, who helped create news feed feature, was viewed as a possible successor to CEO Zuckerberg

Facebook's chief product officer and one of the primary architects of its signature news feed, Chris Cox, said on Thursday he was leaving the company, just days after Mark Zuckerberg revealed a plan to shift the world's biggest social network to an encryption-focused messaging company.

Cox, one of Zuckerberg's earliest employees and closest lieutenants, said in a blogpost he made the announcement "with great sadness" and was leaving after 13 years with the company.