Boeing stock plummets 9% when a panel bursts in midair, causing the FAA to ground numerous 737 Max aircraft

As investors processed the news that the Federal Aviation Administration has directed airlines to ground dozens of Boeing 737 Max 9 aircraft for urgent inspections, shares of Boeing fell by about 9% on Monday.

After a door plug broke out during an Alaska Airlines flight on Friday at around 16,000 feet, the practically brand-new aircraft was flying when the FAA issued the order on Saturday.

Alaska Air’s stock was down almost 4%. Fuselage manufacturer Spirit AeroSystems, which produces the 737 Max, saw a 15% decline.

The tragedy brings Boeing back into the public eye. CEO Dave Calhoun has been making an effort to reassure investors that Boeing is recovering from a series of setbacks, which include two disasters that resulted in 346 fatalities, chaos in the supply chain caused by the pandemic, and several quality issues.

The FAA announced on Saturday that its emergency airworthiness directive, which is applicable to American airlines as well as carriers operating within American territory, will impact about 171 aircraft. Cirium reports that the two biggest users of the 737 Max 9 model—of which more than 200 are in service globally—are United Airlines and Alaska Airlines.

United Airlines has 79 and Alaska has 65 of the 171 planes that have been grounded as a result of the instruction; the remaining 74 are distributed among six other airlines.

Early on Monday, shares of United were up almost 1%.