Company: BA
Filing Date: 2025-12-08
Form Type: S-8 POS
Source: 0001193125-25-311250
Chunk: 0

Company: BOEING CO
Filing Date: 2025-12-08
Form: S-8 POS
Chunk 0
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As filed with the Securities and Exchange Commission on December 8, 2025 Registration No. 333-281498 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 POST-EFFECTIVE AMENDMENT NO.1 ON FORM S-8 TO REGISTRATION STATEMENT ON FORM S-4 UNDER THE SECURITIES ACT OF 1933 THE BOEING COMPANY (Exact name of registrant as specified in its charter)

| Delaware                                 |     |         91-0425694 |
| (State or other jurisdiction of          
 incorporation or organization)           |     |   -I.R.S. Employer 
 Identification No. |
| 929 Long Bridge Drive, Arlington, VA     |     |              22202 |
| (Address of Principal Executive Offices) |     |          -Zip Code |

Spirit AeroSystems Holdings, Inc. Amended and Restated 2014 Omnibus Incentive Plan (Full title of the plan) John C. Demers Corporate Secretary, Vice President & Assistant General Counsel The Boeing Company 929 Long Bridge Drive, Arlington, VA 22202 (Name and address for agent for service) (703) 465-3500 (Telephone number, including area code, of agent for service) Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-acceleratedfiler, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2of the Exchange Act.

| Large accelerated filer |     | ☒ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☐ |     | Smaller reporting company |     | ☐ |
|                         |     |   |     | Emerging growth company   |     | ☐ |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act ☐

EXPLANATORY NOTE

The Boeing Company (the “Company” or “Boeing”) hereby amends its Registration Statement on Form
S-4 (File No. 333-281498) filed with the United States Securities and Exchange Commission (the