Sheryl Sandberg, chief operating officer of Facebook Inc., left, listens during a Senate Intelligence Committee hearing in Washington, D.C., U.S., on Wednesday, Sept. 5, 2018.

Facebook shares had their worst day of the year on Monday, closing down 3.3 percent and extending last week's losses.

The drop came after the company lost its chief product officer, Chris Cox, last week. Analysts at Needham downgraded the stock on Monday over growing concern that more top executives could follow the leads of Cox and Chris Daniels, the head of WhatsApp, who also resigned.

Cox, one of the earliest Facebook employees and someone insiders called the "heart and soul of the company," left as CEO Mark Zuckerberg decided to shift the company's focus towards private messaging instead of open posts on the News Feed.

The stock dropped 2.5 percent on Friday and is down more than 13.3 percent over the past year.