Ascential chief executive Duncan Painter sold £840,000 of stock after a deal to split up the firm sent its shares soaring.
Painter, who has led the media and events group since 2011, sold 300,000 shares for £2.80 each.
He earned £1 million last year and has taken home £7.6 million since the firm was floated in 2016.
Looking ahead: Ascential will be focused on running events such as the Cannes Lions advertising festival
The sale comes after Painter arranged to sell two of Ascential’s businesses for £1.4 billion.
Before it was announced the shares were at £2.13.
Under the deal, Ascential’s consumer research unit would be sold to private equity firm Apax Partners for £700 million and an online commerce division would go to US media group Omnicom.
The remaining company would be focused on running events such as the Cannes Lions advertising festival and Money 20/20, a global financial technology gathering.
If shareholders vote to approve the split it is likely to be completed early next year.
Painter, 53, would join Omnicom under the plans.