In the letter to the SEC - dated October 18 - Boeing said that "significant additional regulatory requirements and/or delays in return to service beyond our current assumption could cause customers to cancel or defer orders, which could also cause us to reduce or temporarily cease 737 Max production". Boeing has taken orders for about 5,000 737 Maxs - worth close to $600bn at list prices. The company told the SEC the "size of the order backlog and management's ability to mitigate potential impacts by shifting planned customer delivery dates" means it "does not expect 737 Max order cancellations due to the grounding to have a material impact to revenues or earnings". Boeing has already racked up costs and charges of $9.2bn since the 737 Max grounding, including compensation to airlines which have been unable to take delivery of aircraft they had ordered. Boeing declined to comment.