UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (date of earliest event reported): August 6 12, 2025

LOGO

ONEOK, Inc.

(Exact name of registrant as specified in its charter)

Oklahoma	001-13643	73-1520922
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)
(State or other jurisdictionof incorporation)	(Commission File Number)	(I.R.S. EmployerIdentification No.)

100 West Fifth Street; Tulsa, OK

(Address of principal executive offices)

74103

(Zip Code)

(918) 588-7000

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each class		Trading symbol(s)		Name of each ~~exchange~~exchangeon on which registered
Common stock, par value of $0.01		OKE		New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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 13(a) of the Exchange Act. ☐

Item 1.01

Entry into a Material Definitive Agreement.

~~Underwriting~~Issuance ~~Agreement~~of Notes

On August 612, 2025, ONEOK, Inc. (“ONEOK”), ~~ONEOK~~completed ~~Partners,~~its ~~L.P.~~previously ~~(“ONEOK~~announced ~~Partners”),~~underwritten ~~ONEOK~~public ~~Partners~~offering ~~Intermediate Limited Partnership~~ (“ONEOK Partners Intermediate”), Magellan Midstream Partners, L.P. (“Magellan”), Elk Merger Sub II, L.L.C. (“Elk Merger Sub II”) and EnLink Midstream Partners, LP (“EnLink” and, together with ONEOK Partners, ONEOK Partners Intermediate, Magellan and Elk Merger Sub II, the “Guarantors”) entered into an underwriting agreement (the “Underwriting Agreement”) with Mizuho Securities USA LLC, Deutsche Bank Securities Inc., PNC Capital Markets LLC, TD Securities (USA) LLC, and Truist Securities, Inc., as representatives of the underwriters named therein (the “Underwriters”), with respect to the issuance and sale (the “Offering”) ~~by ONEOK~~ of $750 million aggregate principal amount of its 4.950% notes due 2032 (the “2032 Notes”), $1.0 billion aggregate principal amount of its 5.400% notes due 2035 (the “2035 Notes”), and $1.25 billion aggregate principal amount of its 6.250% notes due 2055 (the “2055 Notes” and, together with the 2032 Notes and the 2035 Notes, the “Notes”). ~~and~~The ~~such~~ Notes are guaranteed by ONEOK Partners, L.P. (“ONEOK Partners”), ONEOK Partners Intermediate Limited Partnership (“ONEOK Partners Intermediate”), Magellan Midstream Partners, L.P. (“Magellan”), Elk Merger Sub II, L.L.C., a Delaware limited liability company (“Elk Merger Sub II”) and EnLink Midstream Partners, LP, a Delaware limited partnership (together with ONEOK Partners, ONEOK Partners Intermediate, Magellan and Elk Merger Sub II, the “Guarantors”).

~~The~~ONEOK ~~Offering~~intends ~~is expected~~ to ~~close~~use onthe ~~August 12,~~net ~~2025,~~proceeds ~~subject~~from ~~to customary closing conditions. As described in~~ the ~~prospectus~~Offering ~~supplement,~~of ~~dated~~approximately ~~August~~$2.959 6billion, ~~2025,~~after ~~ONEOK~~deducting ~~intends~~underwriting todiscounts ~~use~~and ~~the~~estimated ~~net~~offering ~~proceeds~~expenses, ~~from the Offering~~ to repay all of its outstanding commercial paper, and repay in full at maturity its senior notes due September 15, 2025, together with any accrued and unpaid interest to the date of repayment. ONEOK intends to use any remaining net proceeds from the Offering for general corporate purposes, which may include the repayment of outstanding indebtedness, including the repurchase or redemption of existing notes.

~~The~~Supplemental ~~Underwriting~~Indentures ~~Agreement contains customary representations, warranties~~ and agreements by ONEOK and the Guarantors, and customary conditions to closing, indemnification obligations of each of ONEOK and the Guarantors, on the one hand, and the Underwriters, on the other hand, including for liabilities under the Securities Act of 1933, as amended (the “Securities Act”), obligations of the parties and termination provisions. Notes

~~The~~ONEOK ~~foregoing~~registered ~~description~~the sale of the ~~Underwriting~~Notes ~~Agreement~~with isthe ~~qualified~~Securities inand ~~its~~Exchange ~~entirety~~Commission bypursuant ~~reference~~ to ~~such~~a ~~Underwriting~~Registration ~~Agreement,~~Statement aon ~~copy~~Form ofS-3 ~~which~~(Registration isNo. 333-272782) filed ~~herewith~~on June 20, 2023, as ~~Exhibit~~amended 1by Post-Effective Amendment No. 1 ~~and~~to isForm ~~incorporated~~S-3, ~~herein~~filed byon ~~reference~~September 10, 2024, and Post-Effective Amendment No. 2 to Form S-3, filed on August 6, 2025.

The terms of the Notes and the guarantees related thereto are governed by the Indenture, dated as of January 26, 2012, between ONEOK and U.S. Bank Trust Company, National Association (successor in interest to U.S. Bank National Association), as trustee (the “Trustee”), as supplemented by (i) the Thirty-Third Supplemental Indenture in the case of the 2032 Notes, (ii) the Thirty-Fourth Supplemental Indenture in the case of the 2035 Notes and (iii) the Thirty-Fifth Supplemental Indenture in the case of the 2055 Notes, and in each case dated as of August 12, 2025, by and among ONEOK, the Guarantors and the Trustee (collectively, the “Supplemental Indentures”).

The foregoing description of the Supplemental Indentures is qualified in its entirety by reference to the Supplemental Indentures, copies of which are filed herewith as Exhibits 4.2, 4.3 and 4.4 and are incorporated herein by reference, and to the forms of the Notes, copies of which are filed herewith as Exhibits 4.5, 4.6 and 4.7 and are incorporated herein by reference.

Affiliations

The Underwriters and their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, principal investment, hedging, financing and brokerage activities. The Underwriters and their respective affiliates have provided in the past and may provide from time to time in the future certain commercial banking, financial advisory, investment banking and other services for ONEOK or its subsidiaries for which they will receive customary fees. ~~Certain~~Affiliates of certain of the Underwriters, ~~or their respective affiliates,~~ are also agents and/or lenders under ONEOK’s credit facilities, and dealers under ONEOK’s commercial paper program ~~and holders of ONEOK’s senior notes~~.

~~U.S.~~The ~~Bank Trust Company, National Association, as trustee of the Notes (the “~~Trustee~~”),~~ and certain of its affiliates have from time to time performed, and may in the future perform, various financial advisory, commercial and investment banking services for ONEOK or the Guarantors for which they received or will receive customary fees and expenses. The Trustee is a lender under ONEOK’s credit facility and an affiliate of the Trustee is an Underwriter.

Item 72.0103 ~~Regulation~~Creation FDof ~~Disclosure~~a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

~~ONEOK~~The ~~issued~~information aincluded ~~news~~under ~~release~~“Supplemental onIndentures ~~August 6,~~and ~~2025,~~Notes” ~~announcing~~in ~~the~~Item ~~pricing of the Notes~~1.01 Aabove ~~copy of the press release~~ is ~~attached hereto as Exhibit 99.1 and~~ incorporated herein by reference.

~~The information disclosed in this~~ Item 79.01~~, including Exhibit 99~~.1 ~~hereto,~~Financial isStatements ~~being furnished~~ and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities under that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act or the Exchange Act except as expressly set forth by specific reference in such filing. Exhibits

Item 9.01 Financial Statements and Exhibits.


Exhibit Number		Description

4.1		Indenture, dated January 26, 2012, among ONEOK, Inc. and U.S. Bank National Association, as trustee (incorporated by reference to Exhibit 4.1 to ONEOK, Inc.’s Current Report on Form 8-K filed January 26, 2012 (File No. 1-13643)).

4.2		Thirty-Third Supplemental Indenture, dated as of August 12, 2025, among ONEOK, Inc., ONEOK Partners, L.P., ONEOK Partners Intermediate Limited Partnership, Magellan Midstream Partners, L.P., Elk Merger Sub II, L.L.C., EnLink Midstream Partners, LP and U.S. Bank National Association, as trustee, with respect to 4.950% Notes due 2032.

4.3		Thirty-Fourth Supplemental Indenture, dated as of August 12, 2025, among ONEOK, Inc., ONEOK Partners, L.P., ONEOK Partners Intermediate Limited Partnership, Magellan Midstream Partners, L.P., Elk Merger Sub II, L.L.C., EnLink Midstream Partners, LP and U.S. Bank National Association, as trustee, with respect to 5.400% Notes due 2035.

4.4		Thirty-Fifth Supplemental Indenture, dated as of August 12, 2025, among ONEOK, Inc., ONEOK Partners, L.P., ONEOK Partners Intermediate Limited Partnership, Magellan Midstream Partners, L.P., Elk Merger Sub II, L.L.C., EnLink Midstream Partners, LP and U.S. Bank National Association, as trustee, with respect to 6.250% Notes due 2055.

4.5		Form of Note due 2032 (included in Exhibit 4.1 hereto).

4.6		Form of Note due 2035 (included in Exhibit 4.2 hereto).

4.7		Form of Note due 2055 (included in Exhibit 4.3 hereto).

5.1		Opinion of Latham & Watkins LLP.

5.2		Opinion of GableGotwals.

23.1		Consent of Latham & Watkins LLP (included in Exhibit 5.1 hereto).

23.2		Consent of GableGotwals (included in Exhibit 5.2 hereto).

104		Cover Page Interactive Data File - the cover page XBRL tags are embedded within the Inline XBRL document (contained in Exhibit 101).

(d) Exhibits

Exhibit Number		Description
1.1		Underwriting Agreement, dated August 6, 2025, among ONEOK, Inc., ONEOK Partners, L.P., ONEOK Partners Intermediate Limited Partnership, Magellan Midstream Partners, L.P., Elk Merger Sub II, L.L.C., EnLink Midstream Partners, LP and Mizuho Securities USA LLC, Deutsche Bank Securities Inc., PNC Capital Markets LLC, TD Securities (USA) LLC, and Truist Securities, Inc., as representatives of the underwriters named therein.
99.1		News release issued by ONEOK, Inc. dated August 6, 2025.
104		Cover page interactive data file (embedded within the Inline XBRL document and contained in Exhibit 101).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	ONEOK, INC.
Date: August 8, 2025	By:	/s/ Walter S. Hulse III
Date: August 13, 2025	By:	/s/ Walter S. Hulse III
	Name:	Walter S. Hulse III
	Title:	Chief Financial Officer, Treasurer and Executive Vice President, Investor Relations and Corporate Development

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