Investors across the aviation sector have been spooked by Ryanair's profit warning.
Easyjet is down 5.7%, while British Airways-owner IAG is down more than 3%. Wizzair fell 4.8%, Air France 3.5% and Lufthansa 2.2%.
Ryanair has blamed strikes for lowering its profit guidance and outlook for future trading.
But it seems investors fear there could be more than industrial action behind Ryanair's weaker forecasts, possibly indicating a drop in business across the sector.
The new chief executive of Air France-KLM has pledged to invest half his base salary in the airline's shares as a measure of his confidence in the firm.
Benjamin Smith's basic pay is €900,000 (£800,723) but French news agency AFP reports that he could earn as much as €4.25m if he meets performance targets.
His predecessor Jean-Marc Janaillac was paid a lower amount and stepped down in May after staff voted against a pay offer.
In a video to Air France-KLM employees, Mr Smith, who previously worked at Air Canada, said: "I have already made a personal investment by moving with my family to France.
"Today I have decided to make another investment by investing half my fixed salary in Air France-KLM's share capital. It's a way of demonstrating my confidence in our future success."
Air France-KLM shares have sunk another 5% today after unions gave a frosty reception to the airline's new boss Benjamin Smith, while the airline's Dutch pilots threatened to strike over working conditions.
Unions were openly hostile to the appointment of the Air Canada chief operating officer, accusing the French group of handing control to a foreigner and not protecting Air France's interests.
Mr Smith, who joins next month, will have to contend with labour troubles at Air France that have already cost the airline €335m this year and resulted in the resignation of his predecessor.
Air France shares have fallen more than a third this year.
French unions are due to discuss another round of strike action later this month.
Shares in Air France KLM fell more than 5% in Paris after the airline's biggest pilots union warned that further strikes could result if pay talks with management did not resume.
Philippe Evain, head of the powerful SNPL pilots' union, told Le Parisien newspaper there would be 15 more days of strikes if the airline's new boss did not restart talks over pay conditions.
Air France-KLM has been searching for a new chief executive since the abrupt departure of Jean-Marc Janaillac in May after staff rejected a pay offer aimed at ending the strikes, which have cost €335m.
The French government owns a 14% stake in Air France-KLM, while Delta Airlines and China Eastern Airlines each have an 8.8% holding.
Its shares have fallen more than a third this year.
Air France KLM has reported higher passenger traffic for June.
The company - which has been battling disruption caused by strikes and uncertainty over its management structure - said the group overall carried 9.3 million passengers in June, up 3.7% from a year ago.
The overall load factor, a measure of the extent to which an airline has filled its planes, rose to 89.3% in June from 87.7% last year, it said.
The company is still hunting for a new chief after the abrupt departure of Jean-Marc Janaillac in May
The airline's shares drop 14% after the boss resigns and the government voices doubts over its future.
Read moreFrance's economy minister says the national carrier could 'disappear', as staff begin another strike.
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The CEO says he is resigning after French staff at the strike-hit airline reject a pay deal.
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The French government says it is up to the board of Air France-KLM to work out how the airline deals with a "crisis" after its chief executive announced his resignation over a pay dispute with trade unions.
The French state is the biggest shareholder in Air France-KLM.
"It is up to the board to define how the company gets itself out of this current crisis," the French finance and transport ministries say in a joint statement.
It's yet another day of strike action in France, with both the rail network and flights being hit.
SNCF trains and Air France planes are subject to separate and long-running industrial disputes, with both sets of workers staging a series of two-day stoppages. But today and Tuesday, for the first time, the strikes coincide.
Two-thirds of French trains have been cancelled, while more than one-third of Air France services have been grounded.
French rail workers are protesting against reforms to the state-owned railways that they say will leave them worse off, while Air France employees are calling for a 6% pay rise. The airline has upped its offer from 1% to 2%, but this has been rejected by unions.