This came after an accident Friday where a cabin panel ripped off an Alaska Airlines jet while in mid-air shortly after takeoff, forcing pilots to return to the airport in Portland, Oregon where the flight originated.
The plane, with 171 passengers and six crew on board, landed safely.
Shares of the airline fell in morning trading but were near break-even by midday while those of Spirit AeroSystems which makes the plane part in question, were eight percent lower at lunchtime which was better than their performance at the opening bell.
The 60-pound part of the fuselage that came off covers an optional exit door.
It was recovered on Sunday by a Portland school teacher who found it in his backyard, U.S. National Transportation Safety Board (NTSB) Chair Jennifer Homendy said.
The piece will be thoroughly inspected she said though investigators won't have the recording of the communication of pilots from the cockpit voice recorder or CVR to review.
Currently regulations only require that device to record the last two hours of communication and it was too late when it was recovered - renewing attention on an industry call for longer in-flight recordings.
"There was a lot going on, on the flight deck and on the plane, it's a very chaotic event. The circuit breaker for the CVR was not pulled, the maintenance team went out to get it but it was right at about the two-hour mark and it was completely overwritten. At two hours, it re-records over it, so we have nothing from the CVR."
This incident is just the latest in a series of problems Boeing has had with its Max jets.
Crashes in 2018 and 2019 killed nearly 350 people and led to the MAX's worldwide grounding for 20 months.
In this instance, Boeing confirmed Monday it had already taken steps to get the grounded planes back in the air.
It has shared instructions with airlines about inspecting the grounded fleet, which is a key requirement of regulators before the planes can resume service.
