Boeing Co. (BA) - Get Report  shares jumped the most in more than two months after it posted weaker-than-expected third quarter earnings Wednesday, but said it still expects the troubled 737 MAX aircraft to receive approval from at least one major regulator before the end of the year.

Boeing said earnings for the three months ending in September came in at $2.05 per share, down 42% from the same period last year and four cents shy of the Street consensus forecast. Group revenues, Boeing said, fell 20.55% to $19.98 billion, a figure that modestly topped analysts' estimates of a $19.67 billion tally.

Boeing said it would increases costs related to the grounded 737 MAX by around $900 million, taking the total to around $3.6 billion, but not only expects a return to service in the fourth quarter, but also sees production rising from 42 planes per months to 57 planes per month by the end of 2020.

"Our top priority remains the safe return to service of the 737 MAX, and we're making steady progress," said CEO Dennis Muilenburg. "We've also taken action to further sharpen our company's focus on product and services safety, and we continue to deliver on customer commitments and capture new opportunities with our values of safety, quality and integrity always at the forefront."  

Boeing shares were marked 3.7% higher in early Wednesday trading following the earnings release, the biggest single-session rise since August 22, to change hands at $349.90 each. 

Boeing said overall aircraft orders fell by more than two-thirds, to just 62 units for the third quarter, and trimmed its forecast for 787 Dreamliner production to 12 planes from 14, beginning in late 2020, thanks in part to ongoing U.S.-China trade tensions.

The world's biggest planemaker still has an order backlog of $470 billion, however, thanks to net orders of $16 billion in the third quarter. However, the continued difficulties in sorting out safety issues with the grounded 737 tipped free cash flows into negative territory, with Boeing pegging the figure at -2.42 billion, down from +$4.56 billion for the same period last year.

The difficulties in Boeing's commercial airplanes division lead to the ouster of group executive Kevin McAllister earlier this week, with the company replacing him with the head of global services --and multi-decade Boeing veteran -- Stan Deal.