Ryanair chief executive Michael O’Leary sold five million shares in the airline at €3.75 per share on June 5th.
The sale, before taxes, is worth €18.75 million to Mr O’Leary.
The sale is equivalent to 0.34 per cent of airline's shares and reduces Mr O'Leary's holding to just over 4 per cent or 60 million shares.
Ryanair shares were lower in Dublin in early trade, slipping 2 per cent to €3.67.
Last week Ryanair was defeated in two motions at the Aer Lingus annual general meeting that sought to reduce the pay of the airline's chairman and other board members.
Ryanair holds a stake of 29.8 per cent in Aer Lingus and is the largest shareholder in the former State airline.
Last Tuesday Ryanair announced its first full-year loss in 20 years after it wrote down the value of its stake in Aer Lingus by €222 million, which contributed to a net loss of €169.2 million for the 12 months to the end of March 2009.
Ryanair is predicting profits of between €200 million and €300 million depending on fuel costs and average fares for this year and that passenger numbers will rise by 15 per cent to 67 million.