Shares of Boeing dropped almost 5 percent Friday after an empty 787 experienced a fire at London’s Heathrow Airport.
An unspecified technical issue forced another 787 to turn back to Manchester Airport.
British police said the fire aboard an Ethiopian Airlines plane is being treated as unexplained.
The entire fleet of Boeing 787s was grounded in January for problems involving the plane’s lithium-ion batteries. One caught fire at Boston’s Logan airport.
The planes were cleared to resume flying in April after Boeing redesigned the battery system and got approval for the changes from global aviation regulators.
Boeing shares fell $5.01, or 4.7 percent, to $101.87 in trading Friday. The shares earlier dropped as low as $98.99.
Boeing spokesman Marc Birtel said that the company has personnel looking into the event at Heathrow.
Shares of Boeing suppliers also fell. Precision Castparts fell $3.49, or 1.5 percent, to $233.78. Spirit Aerosystems, which also makes parts for the 787, fell 48 cents, or 2.1 percent, to $22.65.
Citi analyst Jason Gursky said the cause of the fire may not be known until over the weekend. So, the ultimate outcome for Boeing’s stock might wait until Monday. He said a fire related to the plane’s electrical system, even if it is not tied to the lithium-ion battery, would be a concern for investors.