An American Airlines Boeing 737 MAX 8 flight from Los Angeles lands at Reagan National Airport shortly after an announcement was made by the FAA that the planes were being grounded by the United States in Washington, March 13, 2019.

Analysts at Berenberg are calling Boeing a "tough sell" because they see the 737 Max model that had two deadly crashes as "too big to fail" for the company and the industry.

"The 737 MAX is Boeing's most important programme, generating 33% of group revenue, contributing over 50% of profit, and with a backlog of over 4,600 aircraft," Berenberg's Andrew Gollan said in a note Wednesday. "There is no meaningful alternative to support mass switching. It will be unrealistic for the market to reject the platform outright."

Berenberg kept its buy rating on Boeing, betting that the primary factor in the two deadly crashes is the flight control system, which the Federal Aviation Administration is expected to sign off on the software fix next week. The analyst expect the impact to be temporary and the grounded fleet to be back in service in the third quarter.

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