Boeing’s shares fell on Thursday after the US-based firm confirmed it could face delays in its 737 Max deliveries due to a manufacturing issue on its bestselling aircraft.

Boeing said its maintenance personnel found extra holes drilled in the rear pressurization bulkhead of some 737 Max, and that some of the holes were filled with fasteners. The fuselages have been supplied by Spirit AeroSystems.

“This issue will impact near-term 737 deliveries as we conduct inspections to determine the number of airplanes affected, and complete required rework on those airplanes,” Boeing said in a statement.

The announcement sent the plane maker’s shares falling by over 2% in early morning trade on Thursday.

The 737 Max is Boeing’s fastest-selling plane. The company had earlier planned to deliver around 400 to 450 Max planes in 2023.

UAE’s aircraft leasing firm, Dubai Aerospace Enterprise (DAE), had signed through an affiliate this month a deal to acquire dozens of the bestselling aircraft.

The agreement involves the transfer of China Aircraft Leasing Group Holding’s delivery pipeline comprising 64 Boeing 737 Max aircraft.

Last April, Boeing paused deliveries of some 737 Max planes due to a supplier quality issue.

(Writing by Cleofe Maceda; editing by Seban Scaria) seban.scaria@lseg.com