Former EADS Chief Noel Forgeard has been charged with insider trading for selling shares before disclosing production delays of Airbus's A380 jet.
Forgeard was detained by the French police for questioning on Wednesday.
His spokesman, Jean de Belot, told Bloomberg Forgeard expects to prove his innocence.
Forgeard was released after he paid bail.
The insider trading charges do not include allegations Forgeard provided false information to the markets, de Belot says.
Forgeard faces as much as two years in prison and fines equal to ten times the profit on any illegal share sales.
The EADS insider-trading probe was triggered by worsening delays to production of the A380 superjumbo, which sliced a quarter off EADS stock in June 2006.
A number of EADS executives, including Forgeard, exercised their right to sell stock options in March 2006, but the deals fell under the spotlight when EADS unit Airbus announced serious production difficulties with the A380 superjumbo in June that year.
As many as 17 other executives at EADS and its Airbus unit are under investigation in a related civil case.
By Elizabeth Clifford-Marsh