The company’s stock fell as much as 9pc on Monday in New York, as investigations into the incident three days earlier continued.
In London, shares in aerospace parts manufacturer Senior, which works closely with Boeing, dropped more than 2pc.
A door was torn off the side of an Alaska Airlines 737 on Friday in a dramatic blow-out that depressurised the aircraft and forced the flight to turn back and land.
Officials discovered the door plug that was torn off behind a teacher’s house in Portland, Oregon, on Monday.
In the wake of the incident, the US Federal Aviation Administration has ordered airlines to temporarily ground all 171 of the 737 Max 9s currently operating in America, pending inspection.
Analysts said they did not expect the incident to lead to serious problems for Boeing but they were carefully watching the reactions of regulators including those in China, where deliveries of the 737 Max planes have been paused since 2019.
Nicolas Owens, an analyst at Morningstar, predicted no “material financial impact”, but added: “The dramatic nature of the flaw will have the effect of once again calling Boeing’s product governance into question by customers, regulators, and the flying public.”
In another note, analysts at JP Morgan said: “Perhaps the most consequential foreign regulator now is China, where the government has not yet allowed carriers to resume 737 Max deliveries.
“Boeing has seemed on the cusp on resuming deliveries to China for some time, with positive signals in recent months.
“Friday’s accident could delay this process, though Chinese carriers do not fly Max 9s and we are not aware they have ordered any.”
Boeing said it was supporting the regulatory investigation and has stressed “safety is our top priority”.
The company is to host a video conference open to all employees on Tuesday to discuss how it is responding, hosted by president and chief executive Dave Calhoun.
In a statement on Sunday, Mr Calhoun said: “While we’ve made progress in strengthening our safety management and quality control systems and processes in the last few years, situations like this are a reminder that we must remain focused on continuing to improve every day.”
The incident is a fresh blow to Boeing’s 737 Max jets, the fourth generation of the company’s best-selling narrow-body plane that has endured a troubled history.
An earlier model of the Max was previously grounded worldwide, after two crashes in 2018 and 2019 killed 346 people in Indonesia and Ethiopia respectively.
Subsequent investigations revealed that Boeing had failed to share information with regulators about problems with flight control software, which was found to have pushed down the noses of planes automatically.
This time, investigators have said their initial findings do not suggest the Alaska Airlines blowout was caused by any widespread flaw in the 737 Max 9 fleet.