> When Mr. Acton departed Facebook, he forfeited about $900 million in potential stock awards, according to people familiar with the matter. Mr. Koum is expected to officially depart in mid-August, in which case he would leave behind more than two million unvested shares worth about $400 million at Facebook’s current stock price. Both men would have received all their remaining shares had they stayed until this November, when their contracts end.

4 billion dollars of the 22 billion was cash. The remaining 18 billion was in Facebook stock[1]. Most likely, they still have stock in Facebook.

[1] https://www.investopedia.com/articles/investing/032515/whats...