Southwest Airlines 10-K/A 2025-12-31

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

(Mark One)

For the fiscal year ended December 31, 2025

Commission File No. 1-7259

SOUTHWEST AIRLINES CO.

(Exact name of registrant as specified in its charter)

Registrant's telephone number, including area code: (214) 792-4000

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes x No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No o

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.

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 13(a) of the Exchange Act. ¨

Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. x

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. Yes ☐ No x

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). Yes ☐ No x

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes ☐ No x

The aggregate market value of the common stock held by non-affiliates of the registrant was approximately $16,890,396,912 computed by reference to the closing sale price of the common stock on the New York Stock Exchange on June 30, 2025, the last trading day of the registrant’s most recently completed second fiscal quarter.

Number of shares of common stock outstanding as of the close of business on February 3, 2026: 491,317,990 shares

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Definitive Proxy Statement for the Company’s Annual Meeting of Shareholders to be held May 07, 2026, are incorporated into Part III of this Annual Report on Form 10-K.

Explanatory Note

Southwest Airlines Co. (the “Company”) is filing this Amendment No. 1 on Form 10-K/A (this “Amendment”) to its Annual Report on Form 10-K for the fiscal year ended December 31, 2025 (the “Original Form 10-K”) to correct the hyperlink for Exhibit 3.2, the Fifth Amended and Restated Bylaws of the Company, effective May 16, 2025. Unless expressly stated, this Amendment does not reflect events occurring after the filing of the Original Form 10-K and does not modify or update in any way the disclosures contained in the Original Form 10-K, which speak as of the date of the Original Form 10-K. Accordingly, this Amendment should be read in conjunction with the Original Form 10-K and the Company’s other filings with the Securities and Exchange Commission subsequent to the filing of the Original Form 10-K.

Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended, this Amendment contains new certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, which are attached hereto.

PART IV

(a) 1. Financial Statements:

The financial statements included in Item 8. Financial Statements and Supplementary Data above are filed as part of this annual report.

2. Financial Statement Schedules:

There are no financial statement schedules filed as part of this annual report, since the required information is included in the Consolidated Financial Statements, including the notes thereto, or the circumstances requiring inclusion of such schedules are not present.

3. Exhibits:

(1)Certain confidential information contained in this agreement has been omitted because it is both not material and is of the type that the registrant treats as private or confidential.

(2)Management contract or compensatory plan or arrangement.

(3)This exhibit is being furnished rather than filed and shall not be deemed incorporated by reference into any filing, in accordance with Item 601 of Regulation S-K.

A copy of each exhibit may be obtained at a price of 15 cents per page, $10.00 minimum order, by writing to: Investor Relations, Southwest Airlines Co., P.O. Box 36611, Dallas, Texas 75235-1611.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.