Company: SPR
Filing Date: 2025-12-08
Form Type: POSASR
Source: 0001104659-25-119097
Chunk: 1

Company: Spirit AeroSystems Holdings, Inc.
Filing Date: 2025-12-08
Form: POSASR
Chunk 1
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 Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.x

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.¨

Indicate by check mark whether the registrant is a large accelerated
filer, an accelerated filer, a non-accelerated filer, 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-2 of the Exchange Act.

| Large accelerated filer x | 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.¨

<div align='center'>EXPLANATORY NOTE

DEREGISTRATION OF SECURITIES</div>

This post-effective amendment
relates to the registration statement on Form S-3 (File No. 333-275362) (the “Registration Statement”) of Spirit AeroSystems Holdings, Inc., a Delaware corporation
(the “Company”), which was filed with the Securities and Exchange Commission on November 7, 2023, registering the offering
and sale from time to time of an indeterminate amount of Class A common stock, preferred stock and depositary shares.

On December 8, 2025,
pursuant to the Agreement and Plan of Merger, dated June 30, 2024, among the Company, The Boeing Company, a Delaware corporation
(“Parent”), and Sphere Acquisition Corp., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Sub”),
Merger Sub merged with and into the Company, with the Company surviving as a wholly owned subsidiary of Parent (the “Merger”).
In connection with the Merger, the Company has terminated the offering of the Company’s securities pursuant to the Registration
Statement.

In accordance with