What Is Driving The Move In Boeing Stock?

A $10,000 holding in Boeing (BA) at Friday’s close was worth about $9,310 after trading on Monday, September 28, 2026—a drop of roughly 6.9%. The S&P 500 slipped 0.8% that day, so the news was Boeing’s, even if the fallout is limited to Commercial Airplanes. So what sent Boeing stock down on Monday?

A 737 MAX Glitch Delayed The MAX 10

Boeing stock fell over a software glitch in the 737 MAX. The glitch led Boeing’s regulator, the FAA, to hold up approval of the MAX 10. The MAX 10 is the largest version of the 737 MAX. Shares of peers RTX and Northrop Grumman each fell 0.9% that day, about in line with the S&P 500. So the heavy selling was in Boeing.

On Saturday, September 26, 2026, the Wall Street Journal reported a software glitch in the 737 MAX. Boeing said it flagged the glitch on some 737 MAX aircraft. With the glitch, an automated navigation feature could fail during landing. Boeing says there is no safety issue and is working on a software fix.

On Monday, the FAA said it will not certify the MAX 10 until it is satisfied there is no issue. Boeing needs that approval before it can start delivering the MAX 10.

When Can Boeing Start Delivering The MAX 10?

There is no firm date for approval now, because the FAA gave none on Monday. In July, on its fiscal Q2 2026 call, Boeing indicated it expected approval of the smaller 737-7 very soon—a milestone the FAA cleared in August. The MAX 10 was slated to follow, with both versions starting deliveries in 2027. The 2027 start for the MAX 10 now depends on when the FAA is satisfied.

The MAX 10 is part of Commercial Airplanes, Boeing’s largest business. Commercial Airplanes had revenue of $41.5 billion in fiscal 2025.

No sales figure for the MAX 10 alone is available. Its deliveries were not due to start until 2027. So the certification delay itself is about sales from 2027 on, not today’s sales.

Boeing’s Operating Losses Predate The Glitch

Boeing’s operating losses predate the glitch. Over the last twelve months, Boeing’s operating margin was minus 5.4%, against 18.6% for the S&P 500. Operating margin is the share of sales left after running costs. A negative figure means Boeing’s costs were larger than its sales.

The loss has narrowed. A year earlier, the operating margin was minus 12.4%. Commercial Airplanes was still in the red in the second quarter of fiscal 2026. Its operating margin was minus 2.7%.

Boeing’s cash plan dates from July, before the glitch came to light. Management said it remained on track for its 2026 outlook of $1 billion to $3 billion of free cash flow. Free cash flow is the cash left after running and investing in the business. Management also expected third-quarter free cash flow to be positive, in the low hundreds of millions of dollars.

Monday’s fall came from a glitch in the 737 MAX and the risk of a delayed rollout for its newest jet. Boeing’s operating losses and its cash outlook are where they were on Friday. The first sign of harm to today’s business would not be third-quarter cash flow, but rather any downward revision to Boeing’s full-year outlook when it reports.

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