Eight Facebook Inc. insiders combined to sell about $3.9 billion worth of stock since the Cambridge Analytica data-mining scandal first surfaced on March 17. The sales were part of pre-determined trading plans.

Chief Executive Officer Mark Zuckerberg accounted for about 90 percent of the total, according to data from InsiderInsights.com, which analyzes such transactions. The social media giant’s stock fell as much as 24 percent in late trading Wednesday after second-quarter sales and user growth disappointed investors.

(This article has been corrected. The number of insiders who had sold, the amount they sold and Mark Zuckerberg's share of the total were incorrect in the previous version.)

This article was provided by Bloomberg News.