Insiders of IT-giants led by Mark Zuckerburg (Facebook Inc.) are selling their shares with the fastest pace in six years, Bloomberg reports.

Top-managers and directors of Facebook, Amazon.com Inc., Netflix Inc. and Alphabet Inc. (Google) sold this year $4,58 billion of shares. If selloff continues, then this amount can exceed $5 billion in the first half of 2018. It is the highest level since Facebook started selling its stocks in 2012.

Only Zuckerburg alone sold $2,84 shares this year to finance philanthropic projects.

Shares of four companies show good results this year and closed near record high on Monday. For example, Netflix rose by 88%.

Experts think that investors shall monitor further sales to predict future market behavior.