Boeing is reporting losses again, and some are less obvious than others.

The aircraft maker posted a pretax loss of $339 million for the first half of 2026, after briefly turning profitable last year thanks to asset sales. That official figure, however, didn't fully capture Boeing's red ink.

Last December, Boeing completed its biggest acquisition in years, when it paid $8.4 billion to buy its longtime-and then visibly struggling-fuselage supplier, Spirit AeroSystems. Since then, Boeing has uncovered hundreds of millions of dollars in additional liabilities at Spirit beyond what it initially recognized after the deal closed.

The higher obligations amount to real losses, economically speaking, because they mean greater costs for Boeing on deeply unfavorable contracts at below-market prices. Thanks to the quirks of the accounting rules, those losses don't appear on Boeing's income statement and instead are relegated to footnotes about the acquisition.

For investors, it is yet another headwind. Boeing shareholders have endured one setback after another since the stock peaked in 2019. It has fallen by more than half since then. A parade of safety lapses has included two fatal airline crashes, as well as a door-plug blowout during an Alaska Airlines flight in 2024.

Boeing acquired Spirit AeroSystems in a push to bring more of its manufacturing capabilities in-house. It had owned Spirit's factories once before, having sold the operations in 2005 as part of a cost-cutting and outsourcing strategy that meant relying more heavily on outside suppliers before final assembly.

Spirit built the fuselage of the Alaska Airlines plane where the door plug blew off midflight. A federal investigation faulted Boeing for the incident. While no one was killed or seriously injured, the episode forced Boeing to bring more of its supply chain under its own roof.

The numbers related to the Spirit acquisition signal something is amiss. While Boeing paid $8.4 billion-including common stock, loan settlements and debt repayments-it initially allocated $10 billion of the purchase price to the intangible asset goodwill as of Dec. 31 last year.

This means that, after scouring Spirit's business for all identifiable assets and liabilities, Boeing's management determined that the assets' fair value was $1.6 billion less than the combined liabilities. The $10 billion of goodwill represented the difference between the purchase price and Spirit's net identifiable assets, which in this case were negative.

The accounting rules give companies one year to adjust their purchase-price allocations. By midyear, the net deficit had grown, and so did the goodwill. As of June 30, Boeing said the identifiable assets' fair value was $1.9 billion less than the combined liabilities, and it boosted the goodwill to $10.3 billion, which exceeded Boeing's total equity.

The main reason for the change was a $455 million increase in the estimated liability for certain customer contracts, which brought their fair value to about $1.5 billion as of June 30. Boeing described these as "off-market customer contracts" where "the terms of the contract deviated from the terms that a market participant could have achieved."

In plain English, the contracts are a money pit, and they are proving to be more costly than management initially believed.

It is rare for companies to allocate more than 100% of an acquisition's purchase price to goodwill, which isn't amortized. It also raises the question: If the target company's liabilities exceeded the identifiable assets, then why did the acquirer buy it?

The numbers suggest Boeing did so because it had to. About 58% of Spirit's revenue came from Boeing in 2024, its last full year as an independent company. Spirit was Boeing's sole-source supplier for nearly all the products Spirit sold to it, and Spirit itself was drowning in losses. When Boeing bought the company it was preserving its own supply chain, and for that Spirit extracted a large premium.

Boeing's accounting for the Spirit purchase amounts to a double whammy, with goodwill increasing by hundreds of millions of dollars after Boeing uncovered the additional liabilities. But because it identified them within a year of completing the deal, the accounting rules let Boeing avoid a hit to its income statement and absorb the deterioration directly onto the balance sheet by increasing goodwill. (Boeing also made some minor adjustments to the values of other assets and liabilities it acquired from Spirit.)

A Boeing spokesman declined to answer questions about the company's accounting for the purchase. In a statement, he said: "Boeing's integration of former Spirit AeroSystems commercial operations is progressing well and remains an important part of strengthening the company's production system, quality performance and capability to meet future rate increases."

The accounting adjustments tell a more complicated story, though. Even if the acquisition is helping improve production quality, Boeing isn't uncovering hidden financial upside. If it were, management would be finding more value in what it bought as time progressed, not less. And after the one-year true-up window closes, any further bad news will hit the income statement directly.

After all the pain Boeing has inflicted on its shareholders and the public, it can't afford another misstep.