What changed in this filing

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Item 1. Business

2026-02-24 compared with 2025-02-25 · 211 added, 240 removed, 382 unchanged (54% of the section changed)

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We are a leading midstream service provider of gathering, processing, fractionation, transportation, storage and marine export services.

As one of the largest diversified energy infrastructure companies in North America, we are delivering energy that makes a difference in the lives of people in the U.S.

As one of the largest integrated energy infrastructure companies in North America, we are delivering energy that makes a difference in the lives of people in the U.S.

and around the world.

Through our now approximately 60,000-mile pipeline network, we transport the natural gas, NGLs, Refined Products and crude oil that help meet domestic and international energy demand, contribute to energy security and provide safe, reliable and responsible energy solutions needed today and into the future.

Through our approximately 60,000-mile pipeline network, we transport the natural gas, NGLs, Refined Products and crude oil that help meet domestic and international energy demand, contribute to energy security and provide safe, reliable and responsible energy solutions needed today and into the future.

Midstream Value Chain

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For transportation of crude oil, natural gas, Refined Products and NGLs, pipelines are generally the most reliable, lowest cost, least carbon intensive and safest alternative for intermediate and long-haul movements between markets and end users.

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EXECUTIVE SUMMARY

EnLink Controlling Interest Acquisition - On Aug.

28, 2024, we entered into the EnLink Purchase Agreement with GIP to acquire GIP’s interest in EnLink consisting of approximately 43% of the outstanding EnLink Units for $14.90 in cash per unit and 100% of the outstanding limited liability company interests in the managing member of EnLink for $300 million, for total cash consideration of $3.3 billion.

15, 2024, we completed the EnLink Controlling Interest Acquisition.

We used a portion of the proceeds from our September 2024 underwritten public offering of $7.0 billion senior unsecured notes to fund this acquisition.

This acquisition meaningfully increases our scale and integrated value chain within the growing Permian Basin while expanding and extending our asset bases in the Mid-Continent, North Texas and Louisiana regions.

We expect to achieve significant synergies by combining our complementary asset positions.

The operations of EnLink are reported across all four of our existing segments.

EnLink Acquisition - On Nov.

24, 2024, we entered into the EnLink Merger Agreement to acquire all of the publicly held EnLink Units in an all stock, tax-free transaction.

31, 2025, we completed the EnLink Acquisition.

Pursuant to the EnLink Merger Agreement, each common unit of EnLink was exchanged for a fixed ratio of 0.1412 shares of ONEOK common stock, including EnLink Units that were exchanged for all previously outstanding Series B Preferred Units immediately prior to closing.

EnLink Acquisition - On January 31, 2025, we completed the EnLink Acquisition.

Pursuant to the EnLink Merger Agreement, each publicly held common unit of EnLink was exchanged for a fixed ratio of 0.1412 shares of ONEOK common stock, including EnLink Units that were exchanged for all previously outstanding Series B Preferred Units immediately prior to closing.

We issued 41 million shares of common stock with a fair value of $4.0 billion as of the closing date of the EnLink Acquisition.

EnLink is now a wholly owned subsidiary.

For additional information on the EnLink Acquisitions, see Part II, Item 8, Note B of the Notes to Consolidated Financial Statements in this Annual Report.

In addition, see Part 1, Item 1A “Risk Factors” for further discussion of related risks.

Medallion Acquisition - On Aug.

28, 2024, we entered into the Medallion Purchase and Sale Agreement with GIP to acquire all of the equity interests in Medallion for a purchase price of $2.6 billion, subject to customary adjustments, and inclusive of the purchase of additional interests in a Medallion joint venture owned by a separate third party.

31, 2024, we completed the Medallion Acquisition.

We used a portion of the proceeds from our September 2024 underwritten public offering of $7.0 billion senior unsecured notes to fund this acquisition.

This acquisition expands our midstream services for crude oil and condensate in West Texas, specifically in the Midland Basin.

Medallion’s operations are reported in our Refined Products and Crude segment.

For additional information on the Medallion Acquisition, see Part II, Item 8, Note B, of the Notes to Consolidated Financial Statements in this Annual Report.

See Part 1, Item 1A “Risk Factors” for further discussion of risks related to the Medallion Acquisition.

Joint Ventures - On Feb.

4, 2025, we entered into definitive agreements to form joint ventures with MPLX LP (MPLX) to construct a 400 MBbl/d liquified petroleum gas export terminal in Texas City, Texas, and a new 24-inch pipeline from our Mont Belvieu, Texas, storage facility to the new terminal.

Texas City Logistics LLC, the export terminal joint venture, is owned 50% by us and 50% by MPLX, with MPLX constructing and operating the facility.

MBTC Pipeline LLC, the pipeline joint venture, is owned 80% by us and 20% by MPLX, and we will construct and operate the pipeline.

We expect to invest approximately $1.0 billion in these projects.

Interstate Natural Gas Pipeline Divestiture - On Nov.

19, 2024, we entered into a definitive agreement with DT Midstream, Inc.

to sell three of our wholly owned interstate natural gas pipeline systems for total cash consideration of $1.2 billion.

31, 2024, we completed the sale and recognized a gain of $227 million.

This transaction aligns and enhances our capital allocation priorities within our integrated value chain.

Gulf Coast NGL Pipelines Acquisition - In June 2024, we completed the acquisition of a system of NGL pipelines from Easton Energy, a Houston-based midstream company, for approximately $280 million.

This acquisition in our Natural Gas Liquids segment includes approximately 450 miles of liquids products pipelines located in the strategic Gulf Coast market centers for NGLs, Refined Products and crude oil.

A portion of the Easton assets are connected to our Mont Belvieu assets.

We expect to add connections to our Houston-based assets beginning in mid-2025 through the end of 2025.

Business Update and Market Conditions - Over the past year, we experienced significant growth across our value chain due to our recent acquisitions.

Earnings increased in 2024, compared with 2023, due primarily to a full year of earnings from the new Refined Products and Crude segment, higher NGL and natural gas processing volumes in the Rocky Mountain region and the impact of the interstate pipeline divestiture in the Natural Gas Pipelines segment.

For additional information on the EnLink Acquisition, see Part II, Item 8, Note B of the Notes to Consolidated Financial Statements in this Annual Report.

Business Update and Market Conditions - Over the past year, we experienced earnings growth across our value chain due primarily to a full year of earnings from EnLink and Medallion across our segments and higher NGL and natural gas processing volumes.

Our extensive and integrated assets are located in, and connected with, some of the most productive shale basins, as well as refineries and demand centers, in the United States.

Although the energy industry has experienced many commodity cycles, we have positioned ourselves to reduce

exposure to direct commodity price volatility.

With changes in the commodity price environment, we continue to monitor producers’ drilling and completion plans.

Our counterparties are primarily major and independent crude oil and natural gas producers that are able to produce in a lower commodity price environment and continue to find ways to lower costs or enhance production, resulting in profitable projects across our footprint.

With our large asset base, multi-basin exposure and continued asset integration, most of our growth opportunities are not contingent on improving commodity prices.

Although the energy industry has experienced many commodity cycles, we have positioned ourselves to reduce exposure to direct commodity price volatility.

Each of our four reportable segments are primarily fee-based, and our consolidated earnings were approximately 90% fee-based in 2025.

In addition, our Natural Gas Gathering and Processing and Natural Gas Liquids segments are exposed to volumetric risk as a result of drilling and completion activity, severe weather disruptions, operational outages, global crude oil, NGL and natural gas demand and normal volumetric well declines.

Our Refined Products and Crude segment is exposed to volumetric risk due to demand for Refined Products and crude oil in the markets we serve.

Our Natural Gas Pipelines segment is not exposed to significant volumetric risk due to the majority of our capacity being subscribed under long-term, firm fee-based contracts.

For additional information regarding the potential impact of volumetric risk on our business, see Item 1A “Risk Factors.”

Capital Allocation - We continue to focus on maintaining prudent financial strength and flexibility.

In January 2026, our Board of Directors increased our quarterly dividend to $1.07 per share, an increase of 4% compared with the same quarter in the prior year.

In January 2024, our Board of Directors authorized a share repurchase program to buy up to $2.0 billion of our outstanding common stock.

31, 2024, we repurchased $172 million of our outstanding common shares under the program.

31, 2024, we also had $733 million of cash and cash equivalents on hand and $2.5 billion of available capacity under our $2.5 Billion Credit Agreement.

Sustainability and Social Responsibility - Through our participation in the 2024 S&P Global Corporate Sustainability Assessment, we qualified for inclusion in the S&P Global Sustainability Yearbook for the fifth consecutive year, scoring within the top 15% of the Oil and Gas Storage and Transportation industry.

Additionally, in 2024, we received an MSCI ESG Rating of AAA, and our ESG Risk Rating, as assessed by Morningstar Sustainalytics, was in the top 20% of the refiners and pipelines industry.

Natural Gas Gathering and Processing - In our Natural Gas Gathering and Processing segment, earnings increased in 2024, compared with 2023, due to higher volumes in the Rocky Mountain region, as well as the impact of the EnLink Controlling Interest Acquisition from the period of Oct.

15, 2024, to Dec.

In our Natural Gas Gathering and Processing segment, we have a capital project to relocate a 150 MMcf/d processing plant to the Permian Basin from North Texas, which we expect to be in service in the first quarter of 2026.

NGLs - In our Natural Gas Liquids segment, earnings decreased in 2024, compared with 2023, due primarily to the insurance settlement gain in 2023 related to the Medford incident, which was offset partially by higher volumes in the Rocky Mountain region and the impact of the EnLink Controlling Interest Acquisition from the period of Oct.

15, 2024, to Dec.

In December 2024, we announced that we completed construction of our 125 MBbl/d MB-6 NGL fractionator and the looping of the West Texas NGL pipeline.

Additional pump stations, which are expected to be completed in mid-2025, will further increase system capacity to 740 MBbl/d, more than doubling our NGL capacity out of the Permian Basin.

In January 2025, we completed construction of our Elk Creek pipeline expansion project, which is partially in service.

Upon supply of full power, expected in mid-2025, we will have capacity of 435 MBbl/d to transport growing volumes in the Rocky Mountain region, which will bring our total pipeline capacity out of the Rocky Mountain region to 575 MBbl/d.

In August 2024, we announced plans to rebuild our 210 MBbl/d NGL fractionator in Medford, Oklahoma.

Rebuilding at Medford provides strategic benefits that include expansion options that will allow our integrated system to accommodate volume growth from the Permian Basin and the Rocky Mountain and Mid-Continent regions.

The Medford fractionator will also produce butane and natural gasoline for incremental Refined Products and diluent blending opportunities in the Mid-Continent region.

Natural Gas Pipelines - In our Natural Gas Pipelines segment, earnings increased in 2024, compared with 2023, due primarily to the impact of the interstate pipeline divestiture and increased transportation services, as well as the impact of the EnLink Controlling Interest Acquisition from the period of Oct.

15, 2024, to Dec.

We recently reactivated previously idled storage facilities with 3 Bcf of working gas storage capacity in Texas.

In addition, we are in the process of expanding our storage injection capabilities in Oklahoma, which we expect to be complete in the second quarter of 2025.

As a result of the EnLink Acquisitions, we have access to additional natural gas storage assets in Texas and Louisiana.

Refined Products and Crude - This reportable business segment was added in 2023 in conjunction with the Magellan Acquisition.

Our 2023 results include the impact of the Magellan Acquisition from the period of Sept.

25, 2023, to Dec.

Earnings in this segment increased in 2024 due primarily to a full year of operating results following the Magellan Acquisition and due to the recent acquisitions of EnLink and Medallion.

Our 2024 results include the impact of the EnLink Controlling Interest Acquisition from the period of Oct.

15, 2024, to Dec.

31, 2024, and the impact of the Medallion Acquisition from the period of Nov.

1, 2024, to Dec.

In 2024, we benefited from mid-year tariff increases of Refined Products.

Additionally, our optimization and marketing earnings have remained strong due to favorable commodity market conditions.

At the end of the first quarter 2024, we completed the expansion of our Refined Products pipeline to El Paso, Texas.

This expansion provides additional Refined Products supply to growing markets in Texas, New Mexico, Arizona and Mexico.

In July 2024, we announced plans to expand our Refined Products pipeline capacity, connecting Mid-Continent and Gulf Coast supply with the greater Denver area, to meet growing demand and increase connectivity with the Denver International Airport (DIA).

In 2024, our Board of Directors authorized a share repurchase program to buy up to $2.0 billion of our outstanding common stock.

As of December 31, 2025, we repurchased $234 million of our outstanding common shares under the program.

As of December 31, 2025, we also had $78 million of cash and cash equivalents on hand and $3.5 billion of available capacity under our $3.5 Billion Credit Agreement.

Sustainability and Social Responsibility - In 2025, we received an MSCI ESG Rating of AA, and our ESG Risk Rating, as assessed by Morningstar Sustainalytics, was in the top 10% of the refiners and pipelines industry.

Natural Gas Gathering and Processing - In our Natural Gas Gathering and Processing segment, earnings increased in 2025, compared with 2024, due to a full year of earnings from EnLink and higher volumes in the Mid-Continent and Rocky Mountain regions, offset partially by lower realized NGL prices, net of hedging, and the impact from the divestiture of certain nonstrategic assets in 2024.

Our 2024 results include the impact of the EnLink Controlling Interest Acquisition from the period of October 15, 2024, to December 31, 2024.

On May 28, 2025, we completed the Delaware Basin JV Acquisition for $941 million.

Following the completion of the transaction, it is now a wholly owned subsidiary.

In August 2025, we announced plans to construct the Bighorn natural gas processing plant in the Permian Basin, with processing capacity of 300 MMcf/d and the ability to treat natural gas containing high levels of carbon dioxide.

We expect the Bighorn plant, including the carbon dioxide treater, to cost approximately $365 million.

The Bighorn plant is supported by acreage dedications with long-term primarily fee-based contracts and is expected to be completed in mid-2027.

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We are also relocating a 150 MMcf/d processing plant to the Permian Basin from North Texas, which will be completed in the first quarter of 2026, and expanding two existing facilities in the Permian Basin, which will provide an incremental 110 MMcf/d of processing capacity and is expected to be completed in the third quarter of 2026.

Natural Gas Liquids - In our Natural Gas Liquids segment, earnings increased in 2025, compared with 2024, due primarily to a full year of earnings from EnLink, higher exchange services and higher optimization and marketing, offset partially by higher operating costs.

Our 2024 results include the impact of the EnLink Controlling Interest Acquisition from the period of October 15, 2024, to December 31, 2024.

In 2025, we completed construction of our Elk Creek pipeline expansion project, which increased capacity to 435 MBbl/d and brought our total pipeline capacity out of the Rocky Mountain region to 575 MBbl/d.

In February 2025, we announced definitive agreements to form the Texas City Logistics and MBTC Pipeline joint ventures with MPLX LP to construct a 400 MBbl/d liquified petroleum gas export terminal in Texas City, Texas, and a new 24-inch pipeline from our Mont Belvieu, Texas, storage facility to the new terminal.

We expect to invest a total of approximately $1.0 billion into these projects, which are expected to be completed in early 2028.

Natural Gas Pipelines - In our Natural Gas Pipelines segment, earnings decreased in 2025, compared with 2024, due primarily to the impact of the interstate pipeline divestiture in 2024, offset partially by a full year of earnings from EnLink in 2025 and higher optimization and marketing.

Our 2024 results include the impact of the EnLink Controlling Interest Acquisition from the period of October 15, 2024, to December 31, 2024.

In 2025, we, WhiteWater, MPLX LP and Enbridge Inc., through the existing Matterhorn joint venture, announced the new approximately 450-mile, 48-inch Eiger Express Pipeline, designed to transport up to approximately 3.7 Bcf/d of natural gas from the Permian Basin to Katy, Texas.

We expect to invest a total of approximately $350 million into this project, which is expected to be completed in mid-2028.

Refined Products and Crude - In our Refined Products and Crude segment, earnings increased in 2025, compared with 2024, due primarily to a full year of earnings from Medallion and EnLink and lower operating costs, offset partially by lower earnings on BridgeTex associated with the nonrecurring recognition of deferred revenue in 2024.

Our 2024 results include the impact of the EnLink Controlling Interest Acquisition from the period of October 15, 2024, to December 31, 2024, and the impact of the Medallion Acquisition from the period of November 1, 2024, to December 31, 2024.

On July 22, 2025, we completed the BridgeTex Additional Interest Acquisition.

Pursuant to the purchase agreement, we paid approximately $270 million in cash.

Following the completion of the transaction, we now have a 60% ownership interest in BridgeTex.

We have a capital project to expand our Refined Products pipeline capacity, connecting Mid-Continent and Gulf Coast supply with the greater Denver area, to meet growing demand and increase connectivity with the Denver International Airport (DIA).

The project includes construction of a new 230-mile, 16-inch diameter pipeline from Scott City, Kansas, to DIA and the addition or upgrading of certain pump stations along the existing Refined Products pipeline system.

Total system capacity will increase by 35 MBbl/d and will have additional expansion capabilities.

This project is fully subscribed under long-term contracts.

This project is fully subscribed under long-term contracts and is expected to be completed in mid-2026.

See Part II, Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations, in this Annual Report for more information on our capital projects, results of operations, liquidity and capital resources.

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BUSINESS STRATEGY

Our mission is to deliver energy products and services vital to an advancing world.

Our vision is to create exceptional value for our stakeholders by providing solutions for a transforming energy future.

Our vision is to create exceptional value for our stakeholders by providing solutions for an evolving energy future.

Our business strategy is focused on:

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• Maximizing total shareholder return - We plan to grow earnings through high-return capital projects that will allow us to increase our dividend and repurchase shares under our $2.0 billion share repurchase program.

We seek consistent and strong returns on invested capital will allow us to reward our shareholders and provide the means and opportunity to serve our additional stakeholders, including employees and the communities in which we operate.

We seek consistent and strong returns on invested capital that will allow us to reward our shareholders and provide the means and opportunity to serve our additional stakeholders, including employees and the communities in which we operate.

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NARRATIVE DESCRIPTION OF BUSINESS

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• Refined Products and Crude.

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Natural Gas Gathering and Processing

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The Powder River Basin is primarily located in Eastern Wyoming, which includes the NGL-rich Niobrara, Frontier, Turner and Mowry formations.

Mid-Continent region - The Mid-Continent region includes the natural gas and oil-producing Anadarko Basin, which includes the NGL-rich SCOOP and STACK areas, Cana-Woodford Shale, Woodford Shale, Springer Shale, Meramec, Granite Wash, Cherokee and Mississippian Lime formations of Oklahoma.

We have more than 600,000 dedicated acres in the Anadarko Basin, excluding EnLink.

As a result of the EnLink Acquisitions, we have more than doubled our presence in the Mid-Continent region by expanding our existing presence in the Cana-Woodford Shale, Woodford Shale and STACK area, while also beginning to operate in the Arkoma-Woodford Shale.

Permian Basin region - The Permian Basin is a large, natural gas-rich sedimentary basin composed of the Midland Basin, located in West Texas, and the Delaware Basin, located in West Texas and Southeastern New Mexico.

As a result of the EnLink Acquisitions, we have a meaningful presence in the Permian Basin, providing gathering and processing services in the Midland and Delaware Basins.

North Texas region - The North Texas region is located in the Barnett Shale, one of the largest onshore natural gas fields in the United States.

As a result of the EnLink Acquisitions, we now provide gathering and processing services in the Barnett Shale.

Property - Our Natural Gas Gathering and Processing segment includes the following assets, which are wholly owned, except where noted, and exclude EnLink, which is shown separately below:

We have more than 300 thousand dedicated acres in the Powder River Basin.

Mid-Continent region - The Mid-Continent region includes the natural gas and oil-producing Anadarko Basin, which includes the NGL-rich SCOOP and STACK areas, Cana-Woodford Shale, Woodford Shale, Arkoma-Woodford Shale, Springer Shale, Meramec, Granite Wash, Cherokee and Mississippian Lime formations of Oklahoma.

We also have a significant presence in the Barnett Shale of North Texas, one of the largest onshore natural gas fields in the United States, where we provide gathering and processing services.

We have more than 1 million dedicated acres in the Mid-Continent region.

Permian Basin - The Permian Basin is a large, natural gas and oil-rich sedimentary basin composed of the Midland Basin, located in West Texas, and the Delaware Basin, located in West Texas and Southeastern New Mexico.

We have more than 400 thousand dedicated acres in the Permian Basin, providing gathering and processing services in the Midland and Delaware Basins.

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Property - Our Natural Gas Gathering and Processing segment includes the following wholly owned assets:

• 22,600 miles of natural gas gathering pipelines;

• Natural gas processing plants with 1.9 Bcf/d of processing capacity in the Rocky Mountain region and 1.0 Bcf/d in the Mid-Continent region, which were 84% and 77% utilized in 2024 and 2023, respectively.

In addition, we have up to 150 MMcf/d of processing capacity in the Mid-Continent region through a long-term processing services agreement with an unaffiliated third party.

• Natural gas processing plants with 1.9 Bcf/d of processing capacity in the Rocky Mountain region, 3.5 Bcf/d in the Mid-Continent region and 1.8 Bcf/d of processing capacity in the Permian Basin, which were 78% and 84% utilized in 2025 and 2024, respectively.

We calculate utilization rates using a weighted-average approach, adjusting for the dates that assets were placed in or removed from service.

The following are the Natural Gas Gathering and Processing segment assets added as a result of the EnLink Acquisitions:

• 9,000 miles of natural gas gathering pipelines (includes gross mileage of a consolidated, partially owned subsidiary);

• Natural gas processing plants with 1.4 Bcf/d of processing capacity in the Mid-Continent region, 1.7 Bcf/d of processing capacity in the Permian Basin region (includes gross operating capacity of a consolidated, partially owned subsidiary), 0.8 Bcf/d of processing capacity in the North Texas region.

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We are in the process of relocating a 150 MMcf/d natural gas processing plant to the Permian Basin from North Texas and expanding two existing facilities in the Permian Basin, which will provide an incremental 110 MMcf/d of processing capacity.

We also recently announced plans to construct our Bighorn natural gas processing plant, with capacity of 300 MMcf/d, in the Permian Basin.

The additional capacity from these projects is excluded from the assets listed above.

See “Recent Developments” in Part II, Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations, in this Annual Report for more information on our capital projects.

Sources of Earnings - Earnings for this segment are derived primarily from the following types of service contracts:

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After performing these services, we sell the commodities and remit a portion of the commodity sales proceeds to the producers less our contractual fees.

This type of contract represented 76% and 72% of supply volumes in this segment, excluding EnLink, for 2024 and 2023, respectively.

• Fee with POP contracts with producer take-in-kind rights - We purchase a portion of the raw natural gas stream, charge fees for providing the midstream services listed above, return certain commodities to the producer, sell the remaining commodities and remit a portion of the commodity sales proceeds to the producer less our contractual fees.

This type of contract represented 19% of supply volumes in this segment, excluding EnLink, for both 2024 and 2023.

EnLink’s service contracts are primarily fee with POP contracts with producer take-in-kind rights to certain commodities.

• Fee-only - Under this type of contract, we charge a fee for the midstream services we provide based on volumes gathered, processed, treated and/or compressed.

Our fee-only contracts represented 5% and 9% of supply volumes in this segment, excluding EnLink, for 2024 and 2023, respectively.

For commodity sales, we contract to deliver residue natural gas, condensate and/or unfractionated NGLs to downstream customers at a specified delivery point.

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Unconsolidated Affiliates - Our unconsolidated affiliates in this segment are not material.

See Note O of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of our unconsolidated affiliates.

See Note N of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of our unconsolidated affiliates.

Government Regulation - The FERC traditionally has maintained that a natural gas processing plant is not a facility for the transportation or sale of natural gas in interstate commerce and, therefore, is not subject to jurisdiction under the Natural Gas Act.

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See further discussion in the “Regulatory, Environmental and Safety Matters” section.

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Natural Gas Liquids

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Purity NGLs are stored or distributed to our customers, such as petrochemical companies, propane distributors, diluent users, ethanol producers, refineries and exporters.

We provide midstream services to producers of NGLs in the Rocky Mountain region, Mid-Continent region, Permian Basin and Gulf Coast region (including Louisiana) and deliver those products to the market.

We provide midstream services to producers of NGLs in the Rocky Mountain region, Mid-Continent region, Permian Basin and Gulf Coast region and deliver those products to the market.

Our primary markets include the Mid-Continent in Conway, Kansas, the Gulf Coast in Mont Belvieu, Texas, Louisiana and the upper Midwest.

The majority of the pipeline-connected natural gas processing plants in the Williston Basin, Oklahoma, Kansas and the Texas Panhandle as well as a large number in the Permian Basin, Barnett Shale, East Texas and Louisiana regions are connected to our NGL gathering

Through our NGL gathering and distribution pipelines, and fractionation, terminal and storage facilities, we provide needed midstream services while connecting key supply and demand areas.

Property - Our Natural Gas Liquids segment includes the following assets, which are wholly owned, except where noted, and exclude EnLink, which is shown separately below:

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Property - Our Natural Gas Liquids segment includes the following assets, which are wholly owned, except where noted:

• 10,100 miles of gathering pipelines;

• 4,800 miles of distribution pipelines;

• NGL fractionators with combined operating capacity of 960 MBbl/d (includes interests in our proportional share of operating capacity), including 310 MBbl/d in the Mid-Continent region and 650 MBbl/d in the Mont Belvieu, Texas area, which were 92% and 98% utilized in 2024 and 2023, respectively;

• 4,800 miles of distribution pipelines (includes gross mileage of a consolidated, partially owned subsidiary);

• NGL fractionators with combined operating capacity of 1.2 MMBbl/d (includes interests in our proportional share of operating capacity), including 310 MBbl/d in the Mid-Continent region and 890 MBbl/d in the Gulf Coast region, which were 94% and 92% utilized in 2025 and 2024, respectively;

• one isomerization unit with operating capacity of 10 MBbl/d;

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• eight Purity NGLs terminals.

We completed the construction of our 125 MBbl/d MB-6 fractionator, which is included in the assets listed above.

We are in the process of reconstructing our 210 MBbl/d fractionator in Medford, Oklahoma, which is excluded from the assets listed above.

In addition, we have access to 6 MMBbl of combined NGL storage capacity at facilities in Kansas and Texas and 60 MBbl/d of

NGL fractionation capacity in the Gulf Coast through service agreements.

The following are the Natural Gas Liquids segment assets added as a result of the EnLink Acquisitions:

• 800 miles of gathering pipelines (includes gross mileage of a consolidated, partially owned subsidiary);

• NGL fractionators with combined operating capacity of 235 MBbl/d;

• NGL storage facility with operating storage capacity of approximately 10 MMBbl.

In 2025, we completed the expansion of our Elk Creek pipeline, which is included in the assets listed above.

We are in the process of reconstructing our 210 MBbl/d fractionator in Medford, Oklahoma.

We are also in the process of constructing the 24-inch MBTC Pipeline, which is consolidated through a partially owned subsidiary.

These assets are excluded from the assets listed above.

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Unconsolidated Affiliates - We have a 50% ownership interest in Overland Pass, which operates an interstate NGL pipeline system extending 760 miles, originating in Wyoming and Colorado and terminating in Kansas.

We also have a 38.75% ownership interest in Gulf Coast Fractionators, which owns an NGL fractionator in Mont Belvieu, Texas, with 145 MBbl/d of operating capacity that is excluded from the combined operating capacity listed above.

The fractionator resumed operations in 2025.

In 2025, we announced a joint venture with MPLX LP to construct a 400 MBbl/d liquified petroleum gas export terminal in Texas City, Texas.

Texas City Logistics, the export terminal joint venture, is owned 50% by us and 50% by MPLX LP, with MPLX LP constructing and operating the facility.

The export terminal is expected to be completed in early 2028.

Our other unconsolidated affiliates in this segment are not material.

See Note O of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

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See Note N of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

Government Regulation - The operations and revenues of our NGL pipelines are regulated by various state and federal government agencies.

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Residue natural gas is transported or stored for end users, such as large industrial customers, natural gas and electric utilities serving commercial and residential consumers and can ultimately reach international markets through liquified natural gas exports and cross border pipelines.

Our assets are connected to key supply areas and demand centers, including export markets in Mexico via Roadrunner and supply areas in Canada and the United States via our interstate and intrastate natural gas pipelines and Northern Border, which enables us to provide essential natural gas transportation and storage services.

Growing demand from data centers and continued demand from local distribution companies, electric-generation facilities and large industrial companies support low-cost expansions that position us well to provide additional services to our customers when needed.

Intrastate Pipelines and Storage - Our intrastate natural gas pipeline and storage assets are located in Oklahoma, Texas and Kansas.

Our assets are connected to key supply areas and demand centers, including export markets in Mexico via Roadrunner and supply areas in Canada and the United States via our interstate and intrastate natural gas pipelines, Northern Border and Matterhorn, which enables us to provide essential natural gas transportation and storage services.

Growing demand from data centers and continued demand from local distribution companies, electric-generation facilities and large industrial companies position us well for capital projects and low-cost expansions to provide additional services to our customers when needed.

Intrastate Pipelines and Storage - Our intrastate natural gas pipeline and storage assets are located in Oklahoma, Texas, Louisiana and Kansas.

Our Oklahoma intrastate pipeline and storage assets have access to major natural gas production areas in the Mid-Continent region.

Our Texas intrastate pipeline and storage assets have access to major natural gas producing formations in the Texas Panhandle.

Our Texas intrastate pipeline and storage assets have access to major natural gas producing formations in the Texas Panhandle and North Texas.

Our Louisiana intrastate pipeline and storage assets have access to major natural gas production areas in the Haynesville region and access to export markets in the Gulf Coast.

These assets provide shippers access to western markets, several markets to the southeast along the Gulf Coast, including the Houston Ship Channel, the Mid-Continent market to the north and exports to Mexico.

Our storage facilities provide 74 Bcf of working gas storage capacity.

Additionally, as a result of the EnLink Acquisitions, we also have intrastate pipeline and storage assets in Louisiana and North Texas.

Our intrastate pipeline and storage companies primarily include:

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ONEOK Gas Transportation is connected to our ONEOK Gas Storage facilities in Oklahoma, which provide 50 Bcf of working gas storage capacity;

• ONEOK WesTex Transmission, which transports natural gas throughout the western portion of the state of Texas, including the Waha Hub area where other pipelines may be accessed for transportation to western markets, exports to Mexico, several markets to the southeast along the Gulf Coast, including the Houston Ship Channel and the Mid-Continent market to the north.

• ONEOK WesTex Transmission, which transports natural gas throughout the western portion of the state of Texas, including the Waha Hub area where other pipelines may be accessed for transportation to western markets, exports to Mexico, several markets along the Gulf Coast, including the Houston Ship Channel and the Mid-Continent market to the north.

It has access to major natural gas producing formations in the Texas Panhandle, including the Granite Wash formation and Delaware and Midland Basins in the Permian Basin.

ONEOK WesTex Transmission is connected to our ONEOK Texas Gas Storage facilities, which provide 8 Bcf of working gas storage capacity;

• Bridgeline Pipeline, acquired with the EnLink Acquisitions, which provides transportation and storage services to a variety of customers including South Louisiana industrial companies, power companies, utilities and Gulf Coast LNG facilities;

• Louisiana Intrastate Gas (LIG) Pipeline, acquired with the EnLink Acquisitions, which is a natural gas pipeline system providing a fully integrated wellhead to burner tip value chain that includes local gathering, processing, transmissions and treating services to Louisiana producers.

The LIG Pipeline has access to the Haynesville shale producing area and connects to several other natural gas pipelines, providing additional system supply, and to the Jefferson Island storage facility;

• Acacia Pipeline, acquired with the EnLink Acquisitions, which provides transportation services to connect production from the Barnett Shale to markets in North Texas.

Interstate Natural Gas Pipeline Divestiture - On Nov.

19, 2024, we entered into a definitive agreement with DT Midstream, Inc.

to sell three of our wholly owned interstate natural gas pipeline systems, including Guardian and Viking, located in the Upper Midwest, and Midwestern Gas Transmission Company, located between Tennessee and the Chicago Hub near Joliet, Illinois.

31, 2024, we completed the sale of these assets.

Interstate Pipelines - Sabine Pipeline was acquired with the EnLink Acquisitions and is an interstate natural gas pipeline that transports natural gas between Port Arthur, Texas, and the Henry Hub located in Erath, Louisiana.

• Bridgeline Pipeline, which provides transportation and storage services to a variety of customers including South Louisiana industrial companies, power companies, utilities and Gulf Coast LNG facilities.

Bridgeline Pipeline is connected to our Napoleonville and Sorrento storage facilities, which provide 8 Bcf and 3 Bcf of working gas storage capacity, respectively;

• Louisiana Intrastate Gas Pipeline, which is a natural gas pipeline system that has access to the Haynesville Shale and connects to several other natural gas pipelines, including Bridgeline Pipeline, providing additional system supply, and to our Jefferson Island Storage Hub facility, which provides 2 Bcf of working gas storage capacity;

• Acacia Pipeline, which provides transportation services to connect production from the Barnett Shale to markets in North Texas.

Interstate Pipelines - Sabine Pipeline is an interstate natural gas pipeline that transports natural gas between Port Arthur, Texas, and the Henry Hub located in Erath, Louisiana.

The Sabine Pipeline also owns and operates the Henry Hub, the official delivery mechanism and pricing point for Chicago Mercantile Exchange’s NYMEX natural gas futures.

Property - Our Natural Gas Pipelines segment includes the following wholly owned assets and exclude EnLink, which is shown separately below:

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Property - Our Natural Gas Pipelines segment includes the following wholly owned assets:

• 8,300 miles of natural gas pipelines, which were 91% and 97% subscribed in 2025 and 2024, respectively;

• seven underground natural gas storage facilities with 61 Bcf of total active working natural gas storage capacity which were 75% and 76% subscribed in 2024 and 2023, respectively.

Our storage includes two underground natural gas storage facilities in Oklahoma, two underground natural gas storage facilities in Kansas and three underground natural gas storage facilities in Texas.

The following are the Natural Gas Pipeline segment assets added as a result of the EnLink Acquisitions:

• 3,200 miles of natural gas pipelines;

• four underground natural gas storage facilities with approximately 13 Bcf of total active working natural gas storage capacity.

• eleven underground natural gas storage facilities with 74 Bcf of total active working natural gas storage capacity which were 83% and 75% subscribed in 2025 and 2024, respectively.

Our storage includes two underground natural gas storage facilities in Oklahoma, two underground natural gas storage facilities in Kansas, four underground natural gas storage facilities in Texas and three underground natural gas storage facilities in Louisiana.

We are expanding our Jefferson Island Storage Hub facility in Louisiana to increase the working gas storage capacity from 2 Bcf to 11 Bcf, which is excluded from the working natural gas storage capacity listed above.

This project is expected to be completed in two phases, with the first phase expected to be completed in the second half of 2028 and the second phase to be completed in early 2029.

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Sources of Earnings - Earnings for our Natural Gas Pipelines segment are derived primarily from fee-based services and our business activities are categorized as follows:

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◦ Firm service - Customers reserve a fixed quantity of pipeline capacity for a specified period of time, which obligates the customer to pay regardless of usage.

Under this type of contract, the customer pays a monthly fixed fee and incremental fees, known as commodity charges, which are based on the actual volumes of

natural gas they transport or store.

Under this type of contract, the customer pays a monthly fixed fee and incremental fees, known as commodity charges, which are based on the actual volumes of natural gas they transport or store.

Under the firm service contract, the customer generally is guaranteed access to the capacity they reserve.

Our firm service contracts typically have terms longer than one year.

◦ Interruptible service - Under interruptible service transportation agreements, the customer may utilize available capacity after firm service requests are satisfied.

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Customers reserve the right to park or loan natural gas based on a specified quantity, including injection and withdrawal rights when capacity is available.

• Optimization and marketing - As a result of the EnLink Acquisitions, we also derive earnings from providing natural gas marketing and optimization for our customers.

• Optimization and marketing - We utilize our assets, contract portfolio and market knowledge to capture location and price differentials through the purchase and sale of natural gas.

Unconsolidated Affiliates - Our Natural Gas Pipelines segment includes the following unconsolidated affiliates:

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We are the operator of Roadrunner.

• As a result of the EnLink Acquisitions, 15% ownership interest in Matterhorn, a bidirectional pipeline, which has capacity to transport 2.5 Bcf/d of natural gas from the Waha Hub to Katy, Texas.

See Note O of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

• 15% ownership interest in Matterhorn, a bidirectional pipeline, which has capacity to transport 2.5 Bcf/d of natural gas from the Waha Hub to Katy, Texas.

WhiteWater will construct and operate the pipeline, which is expected to be completed in mid-2028.

Our total ownership interest in the pipeline will be 25.5%, which includes a 15% interest held directly in the Eiger joint venture with the remainder held through Matterhorn.

See Note N of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

Government Regulation - Interstate - Our interstate natural gas pipelines are regulated under the Natural Gas Act, which gives the FERC jurisdiction to regulate virtually all aspects of this business, such as transportation of natural gas, rates and charges for services, construction of new facilities, depreciation and amortization policies, acquisition and disposition of facilities and the initiation and discontinuation of services.

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While we have flexibility in establishing natural gas transportation rates with customers, there is a maximum rate that we can charge our customers in Oklahoma and Kansas and for the services regulated by the FERC.

In Texas and Kansas, natural gas storage may be regulated by the state and by the FERC for certain types of services.

In Texas and Kansas, natural gas storage may be regulated by the state and by the FERC for certain

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types of services.

In Oklahoma, natural gas storage operations are not subject to rate regulation by the state, and we have market-based rate authority from the FERC for certain types of intrastate services.

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Overview of Operations - Our Refined Products and Crude segment is principally engaged in the transportation, storage and distribution of Refined Products and crude oil.

As a result of the EnLink Acquisitions and the Medallion Acquisition, we are also engaged in the gathering of crude oil .

Crude oil pipelines gather and transport crude oil to refineries, export facilities and demand centers.

Throughout our distribution system, terminals play a key role in facilitating product movements and marketing by providing storage, distribution, blending and other ancillary services.

We are also engaged in the gathering of crude oil .

Products transported on our Refined Products pipeline system include gasoline, distillates, aviation fuel and certain NGLs.

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Our Refined Products pipeline system is one of the longest common carrier pipeline systems for Refined Products in the United States, extending from the Texas Gulf Coast and covering a 15-state area across the central and western United States.

Our crude oil assets are strategically located to transport and store crude oil and are connected to multiple trading and demand centers.

We have existing crude oil pipelines in Kansas and Oklahoma, and from the Permian Basin in West Texas to our East Houston terminal.

Our crude oil assets are strategically located to gather, transport and store crude oil and are connected to refineries, export facilities and multiple trading and demand centers.

We have crude oil gathering pipelines in the Permian Basin and Mid-Continent region.

Our crude oil transportation pipelines are located in Kansas and Oklahoma, and from the Permian Basin in West Texas to our East Houston terminal.

Throughout our Refined Products and crude oil distribution systems, terminals play a key role in facilitating product movements and marketing by providing storage, distribution, blending and other ancillary services.

Our Houston distribution system connects our East Houston terminal through several interchanges to various points, including multiple refineries throughout the Houston area and crude oil import and export facilities.

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Our Corpus Christi terminal provides terminalling services and includes our splitter.

As a result of the EnLink Acquisitions and the Medallion Acquisition, we acquired crude oil gathering pipelines and crude oil storage facilities in the Permian Basin and the Mid-Continent region.

Property - Our Refined Products and Crude segment includes the following wholly owned assets, which exclude EnLink and Medallion, which are shown separately below:

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Property - Our Refined Products and Crude segment includes the following wholly owned assets:

• 9,800 miles of Refined Products pipelines;

• 1,100 miles of crude oil pipelines;

• 1,100 miles of crude oil transportation pipelines;

• 2,100 miles of crude oil gathering pipelines;

• 53 Refined Products terminals;

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• 100 MMBbl of operating storage capacity.

The following are the Refined Products and Crude segment assets added as a result of the EnLink Acquisitions and the Medallion Acquisition:

• 2,100 miles of crude oil gathering pipelines;

• 2 MMBbl of operating storage capacity.

We are in the process of constructing our greater Denver area pipeline expansion project.

The project includes construction of a new 230-mile, 16-inch diameter pipeline from Scott City, Kansas, to Denver International Airport and the addition or upgrading of certain pump stations and will increase total system capacity by 35 MBbl/d and have additional expansion capabilities.

We are in the process of constructing our greater Denver area Refined Products pipeline expansion project.

The project includes construction of a new 230-mile, 16-inch diameter pipeline from Scott City, Kansas, to DIA and the addition or upgrading of certain pump stations and will increase total system capacity by 35 MBbl/d and have additional expansion capabilities.

This project is excluded from the assets listed above.

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Sources of Earnings - Earnings in this segment are derived primarily from transportation, storage and terminal services and product sales:

• Transportation services - We generate revenue from tariffs on volumes gathered and transported on our Refined Products and crude oil pipeline systems.

These transportation tariffs vary depending upon where the product originates and where ultimate delivery occurs.

• Transportation services - We utilize our Refined Products and crude oil pipeline systems to gather and transport products.

The fees we charge vary depending upon where the product originates and where ultimate delivery occurs.

Transportation fees are in published tariffs filed with the FERC or the appropriate state agency or established by negotiated rates.

• Storage and terminal services - We generate additional revenue from providing pipeline capacity and tank storage services, as well as providing services such as terminalling, ethanol and biodiesel unloading and loading, and additive injection, which are performed under short-term and long-term agreements.

• Optimization and marketing - At times, we obtain Refined Products and crude oil and utilize our assets, contract portfolio and market knowledge to capture location, product and seasonal price differentials through liquids blending and purchases and sales of product, including transmix, which is a mixture that forms when different Refined Products are transported in pipelines.

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• Optimization and marketing - We utilize our assets, contract portfolio and market knowledge to capture location, product and seasonal price differentials through liquids blending and purchase and sale of Refined Products and crude oil, including transmix, which is a mixture that forms when different Refined Products are transported in pipelines.

In some crude oil transportation contracts, we purchase the product at the wellhead and deduct contractual fees related to the gathering and transportation services we perform to move the product to market.

Unconsolidated Affiliates - Our Refined Products and Crude segment includes the following unconsolidated affiliates:

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• a 40% ownership interest in Saddlehorn, which owns an undivided joint interest in an approximately 600-mile pipeline, with transport capacity of up to 290 MBbl/d of crude oil from the Denver-Julesburg Basin and Rocky Mountain region to storage facilities in Cushing, including our Cushing terminal;

• a 25% ownership in MVP, which owns a Refined Products marine storage terminal along the Houston Ship Channel in Pasadena, Texas, including more than 5 MMBbl of storage, two ship docks and truck loading facilities.

• a 25% ownership in MVP, which owns a Refined Products marine terminal along the Houston Ship Channel in Pasadena, Texas, including more than 5 MMBbl of storage, two ship docks and truck loading facilities.

Our other unconsolidated affiliates in this segment are not material.

See Note O of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

See Note N of the Notes to Consolidated Financial Statements in this Annual Report for additional discussion of unconsolidated affiliates.

Government Regulation - Our interstate common carrier pipelines are subject to rate regulation by the FERC under the Interstate Commerce Act, the Energy Policy Act of 1992 and related rules and orders.

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Supply and Demand - Supply for each of our segments depends on crude oil and natural gas drilling and production activities, which are driven by the strength of the economy and impacts of geopolitical events;

crude oil, natural gas, NGL and Refined

Products prices;

crude oil, natural gas, NGL and Refined Products prices;

the demand for each of these products from end users;

changes in gas-to-oil ratios and the decline rate of existing production;

changes in gas-to-oil ratios;

refinery maintenance cycles;

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Demand for natural gas, NGLs, Refined Products and crude oil is also impacted by global macroeconomic factors.

Commodity Prices - Our earnings are primarily fee-based in all of our segments;

See additional discussion regarding the impacts of the recent market conditions on supply and demand under "Business Update and Market Conditions" in our Executive Summary at the beginning of this Item 1.

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Commodity Prices - Although the energy industry has experienced many commodity cycles, we have positioned ourselves to reduce exposure to direct commodity price volatility.

Our earnings are primarily fee-based in all of our segments;

however, we are exposed to some commodity price risk.

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and the relative price differential between natural gas, NGLs and individual Purity NGLs, which affect our NGL purchases and sales, our exchange services, transportation and storage services, and optimization and marketing financial results.

NGL storage revenue may be affected by price volatility and forward pricing of NGL physical contracts versus the current price of NGLs on the spot market.

We are also exposed to changes in the price of power, which can impact our fractionation and transportation costs.

In our Natural Gas Pipelines segment, we are exposed to minimal commodity price risk associated with (i) changes in the price of natural gas, which impact our fuel costs and retained fuel in-kind received for our compression services;

and (ii) the differential between forward pricing of natural gas physical contracts and the price of natural gas on the spot market, which may affect customer demand for our natural gas storage services.

In our Natural Gas Pipelines segment, we are exposed to some commodity price risk associated with changes in the price of natural gas and location differentials primarily from our optimization and marketing activities.

In our Refined Products and Crude segment, we are exposed to some commodity price risk, including product price and location differentials primarily from our optimization and marketing activities, as well as product retained during the operations of our pipelines and terminals.

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• cost of and access to capital.

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We have remained competitive by executing strategic acquisitions;

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and improving operating efficiency.

Our and our competitors’ infrastructure projects may affect commodity prices and could displace supply volumes from the Mid-Continent and Rocky Mountain regions and the Permian Basin where our assets are located.

Our infrastructure projects, along with those of our competitors, may affect commodity prices and could displace supply volumes from the Mid-Continent and Rocky Mountain regions and the Permian Basin where our assets are located.

We believe our assets are located strategically, connecting diverse supply areas to market and demand centers.

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See discussion regarding our customer credit risk under “Counterparty Credit Risk” in Part II, Item 7A, Quantitative and Qualitative Disclosures about Market Risk, in this Annual Report.

For additional information regarding the potential impact of market conditions and seasonality on our business, see Item 1A “Risk Factors.”

Through ONEOK Leasing Company, L.L.C.

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Failure to comply with these laws, regulations, licenses and permits may expose us to fines, penalties, reputational harm, claims or lawsuits from third parties, and/or interruptions in our operations that could be material to our results of operations or financial condition.

also incur material costs for cleanup of spills or releases of hazardous substances.

We may also incur material costs for cleanup of spills or releases of hazardous substances.

In addition, emissions controls and/or other regulatory or permitting mandates under the Federal Clean Air Act, as amended (Clean Air Act), and other similar federal and state laws could require unexpected capital expenditures at our facilities.

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GHG Emissions - In 2024, GHG emissions were approximately 3.9 million metric tons of carbon dioxide equivalents of Scope 1 emissions and 3.6 million metric tons of carbon dioxide equivalents of Scope 2 emissions.

Scope 1 emissions originate from the combustion of fuel in our equipment, such as compressor engines and heaters, as well as fugitive methane emissions.

Scope 1 emissions originate from

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the combustion of fuel in our equipment, such as compressor engines and heaters, as well as fugitive methane emissions.

Scope 2 emissions are generated from purchased power sources.

In 2021, we announced a companywide absolute GHG emissions reduction target of 2.2 million metric tons of carbon dioxide equivalents from our combined Scope 1 and Scope 2 GHG emissions by 2030 for our legacy ONEOK assets.

The target represents a 30% reduction in combined operational Scope 1 and location-based Scope 2 GHG emissions attributable to ONEOK assets as of Dec.

31, 2024, we have achieved reductions totaling approximately 1.7 million met ric tons of the targeted 2.2 million metric tons of carbon dioxide equivale nts, primarily as a result of methane emissions mitigation, system utilization and optimizations, electrification of certain natural gas compression equipment and lower carbon-based electricity in states in which we operate.

The target represents a 30% reduction in combined operational Scope 1 and location-based Scope 2 GHG emissions attributable to ONEOK assets as of December 31, 2019.

As of December 31, 2025, we have achieved reductions totaling approximately 1.8 million metric tons of th e targeted 2.2 million metric tons of carbon dioxide equivale nts, primarily as a result of methane emissions mitigation, system utilization and optimizations, electrification of certain natural gas compression equipment and lower carbon-based electricity in states in which we operate.

GHG emission reductions as reported may be modified, updated, changed or supplemented based on available information.

For the years ended Dec.

31, 2024, 2023 and 2022, we did not have any material dedicated capital expenditures specifically for climate-related projects, nor did we purchase or sell carbon credits or offsets.

For the years ended December 31, 2025, 2024 and 2023, we did not have any material dedicated capital expenditures specifically for climate-related projects, nor did we purchase or sell carbon credits or offsets.

Progress to date on our goal has been accomplished through routine capital projects and asset optimizations that were primarily performed for operational improvements that inherently improved our emissions profile.

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We are a participant in the American Petroleum Institute’s The Environmental Partnership and are enrolled in environmental performance programs that are designed to further reduce emissions using proven, cost-effective controls.

United States Department of Transportation Pipeline and Hazardous Materials Safety Administration ( PHMSA) - On Jan.

17, 2025, the PHMSA issued a final rule, which has been submitted to the Federal Register underscoring to pipeline and pipeline facility operator’s requirements to minimize methane emissions in the Protecting our Infrastructure of Pipelines and Enhancing Safety (PIPES) Act of 2020.

United States Department of Transportation Pipeline and Hazardous Materials Safety Administration ( PHMSA) - On January 17, 2025, the PHMSA issued a final rule, which has been submitted to the Federal Register underscoring to pipeline and pipeline facility operator’s requirements to minimize methane emissions in the Protecting our Infrastructure of Pipelines and Enhancing Safety (PIPES) Act of 2020.

The PIPES Act directs pipeline operators to update their inspection and maintenance plans to address the elimination of hazardous leaks and to minimize natural gas releases from pipeline facilities.

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The additional cost to gather and report this emission data did not have, and we do not expect it to have, a material impact on our results of operations, financial position or cash flows.

In 2024, the EPA finalized its rule targeting oil and gas section emissions of greenhouse gases (primarily methane) and volatile organic compounds (VOCs).

The rule includes (i) new source performance standards codified in 40 C.F.R.

Part 60 Subpart OOOOb for new sources (i.e., facilities that commence construction, reconstruction, or modification after Dec.

6, 2022), (ii) emission guidelines codified in 40 C.F.R.

Part 60 Subpart OOOOc that states must use to develop performance standards for existing sources (i.e., facilities that existed on or before Dec.

This final rule was challenged in court by states and industry stakeholders, which litigation is ongoing.

In September 2025, the EPA proposed to permanently remove program obligations for 46 source categories of the Greenhouse Gas Reporting Program (GHGRP).

Under the proposal, facilities, suppliers and underground injection sites under these 46 source categories would no longer report to the EPA after reporting year 2024.

In accordance with the new administration’s Executive Order (E.O.) 14192, “Unleashing Prosperity Through Deregulation,” the EPA has reviewed the GHGRP and determined that there is no statutory requirement to collect GHG emissions information for sectors other than the petroleum and natural gas source category (subpart W) segments subject to the Waste Emissions Charge (WEC) rule.

For subpart W, the EPA’s proposed amendments consist of two parts.

First, the EPA is proposing to permanently remove program obligations for facilities in the natural gas distribution segment.

Under the proposal, facilities in the natural gas distribution segment of subpart W would no longer report to the EPA after reporting year 2024.

Second, for the remaining nine segments of subpart W, the EPA is proposing to suspend program reporting requirements until reporting year 2034 in accordance with the One Big Beautiful Bill Act.

We do not anticipate the proposal to materially change our internal reporting requirements or external disclosures of our GHG emissions.

In 2024, the EPA finalized its rule targeting oil and gas sector emissions of greenhouse gases (primarily methane) and volatile organic compounds (VOCs).

The rule includes (i) new source performance standards (NSPS) codified in 40 C.F.R.

Part 60 Subpart OOOOb for new sources (i.e., facilities that commence construction, reconstruction, or modification after December 6, 2022), (ii) emission guidelines codified in 40 C.F.R.

Part 60 Subpart OOOOc that states must use to develop performance standards for existing sources (i.e., facilities that existed on or before December 6, 2022).

This final rule was challenged in

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court by states and industry stakeholders and that litigation is ongoing.

In addition, in January 2025, the new administration issued an executive order directing the heads of all federal agencies to identify and begin the processes to suspend, revise or rescind all agency actions that are unduly burdensome on the identification, development or use of domestic energy resources.

Consequently, future implementation and enforcement of the final rule remain uncertain.

In July 2025, the EPA issued an interim final rule (IFR) to extend multiple compliance deadlines under NSPS OOOOb/c.

On December 3, 2025, the EPA issued a final rule that largely affirms the extended compliance deadlines announced in the IFR.

At this time, we do not anticipate a material impact to our planned capital, operations and maintenance costs resulting from compliance with the current or pending regulations and proposed EPA actions.

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The ability to incorporate increasing volumes of renewable fuel components into fuel products and the availability of RINs may be limited, which could increase our RFS compliance costs or limit our ability to blend.

In 2024, the EPA finalized changes to the federal gasoline distribution reg ulations.

We do not anticipate a material im pact to our planned capital, operations and maintenance costs resulting from compliance with the current regulations.

We are subject to the EPA federal gasoline distribution reg ulations.

We do not anticipate a material impact to our planned capital, operations and maintenance costs resulting from compliance with the current regulations.

Additionally, we are subject to the EPA’s fuels compliance regulations.

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Circuit, and the new administration issued an executive order directing the heads of all federal agencies to identify and begin the processes to suspend, revise or rescind all agency actions that are unduly burdensome on the identification, development or use of domestic energy resources.

In May 2025, aligning with the Congressional resolution to disapprove the WEC rule, the EPA removed the fee implementation regulations from the Code of Federal Regulations.

However, the IRA still requires the EPA to collect methane fees, but the implementation has been postponed until reporting year 2034 in accordance with the One Big Beautiful Bill Act.

Consequently, future implementation and enforcement of these rules remain uncertain at this time.

Based on text in the IRA and a related rule that the EPA finalized in November 2024 that will require payment of Methane Fees to the EPA beginning in 2025 (for 2024 reported emissions), the 2024 Methane Fees, if implemented, will not have a material impact on our results of operations, financial position or cash flows.

We believe it is likely that continued future governmental legislation and/or regulation may require us to limit GHG emissions associated with our operations, pay additional fees associated with our GHG emissions or purchase allowances for such emissions.

However, we cannot predict precisely what form these future regulations will take, the stringency of the regulations, when they will become effective or the impact on our capital expenditures, competitive position and results of operations.

In addition to activities on the federal level, state and regional initiatives could also lead to the regulation of GHG emissions sooner than or independent of federal regulation, these regulations could be more stringent than requirements in any future federal legislation and/or regulation.

On February 12, 2026, the EPA issued a final rule eliminating the 2009 GHG endangerment finding, which underpins U.S.

federal regulation of GHG emissions under the Clean Air Act.

The final rule is expected to be subject to extensive litigation, and the impact is difficult to predict at this time.

In addition to activities on the federal level, state and regional initiatives could also lead to the regulation of GHG emissions sooner than or independent of federal regulation, and these regulations could be more stringent than requirements in any future federal legislation and/or regulation.

We monitor all relevant legislation and regulatory initiatives to assess the potential impact on our operations and otherwise take steps to limit GHG emissions from our facilities, including methane.

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We are not currently required to comply with a substantial portion of the RCRA requirements as our operations routinely generate only small quantities of hazardous waste, and we are not a hazardous waste treatment, storage or disposal facility operator that is required to obtain a RCRA

While the RCRA currently exempts a number of types of waste from being subject to hazardous waste requirements, including many oil and gas exploration and production wastes, the EPA could consider the adoption of stricter disposal standards for non-hazardous waste.

Moreover, it is possible that additional waste, which could include non-hazardous waste currently generated during operations, may be designated as hazardous waste.

Hazardous waste is subject to more rigorous and costly storage and disposal requirements than non-hazardous waste.

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Moreover, it is possible that additional waste, which could include nonhazardous waste currently generated during operations, may be designated as hazardous waste.

Hazardous waste is subject to more rigorous and costly storage and disposal requirements than nonhazardous waste.

Changes in the regulations could materially increase our operating expenses.

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The Pipeline Safety, Regulatory Certainty and Job Creation Act of 2011 (the 2011 Pipeline Safety Act) increased maximum penalties for violating federal pipeline safety regulations, directs the United States Department of Transportation (DOT) and Secretary of Transportation to conduct further review or studies on issues that may or may not be material to us and may result in the imposition of more stringent regulations.

Penalty amounts have since been regularly adjusted for inflation with the most recent adjustment taking effect on Dec.

In 2015 through 2022, PHMSA issued notices of proposed rulemaking for hazardous liquid pipeline safety regulations, natural gas transmission and gathering lines and underground natural gas storage facilities.

For natural gas and natural gas gathering pipelines, the new proposed regulations became known as “the Mega Rule.” The Mega Rule increased requirements for operating and maintenance, integrity management, public awareness and civil/criminal penalties with full compliance deadlines extending into 2035;

Penalty amounts have since been regularly adjusted for inflation with the most recent adjustment taking effect on December 30, 2025.

For the years 2020 through 2023, PHMSA’s Mega Rule increased requirements for operating and maintenance, integrity management, public awareness and civil/criminal penalties with full compliance deadlines extending into 2035;

however, we do not anticipate a material impact to our planned capital or operations and maintenance costs resulting from compliance with these requirements.

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Results of periodic mechanical integrity tests must also be reported to the RRC.

In addition, our underground natural gas storage caverns in Louisiana are subject to the jurisdiction of the Louisiana Department of Natural Resources (LDNR).

In recent years, LDNR has put in place more comprehensive regulations governing underground hydrocarbon storage in salt caverns, and we believe we are in substantial compliance with these newer regulations.

PHMSA regulates safety issues related to downhole facilities located at both intrastate and interstate underground natural gas storage facilities.

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State entities that exercise jurisdiction over our underground natural gas storage facilities include the RRC (for our underground natural gas storage facilities in Texas) and LDNR (for our underground natural gas storage facilities in Louisiana).

We do not believe continued compliance with safety standards and other requirements applicable to our underground natural gas storage facilities will have a material impact on results of operations, financial position or cash flows.

In July 2022, a fire occurred at our 210 MBbl/d Medford, Oklahoma, NGL fractionation facility.

All personnel were safe and accounted for with temporary evacuations of local residents taken as a precautionary measure.

As a result of the incident, the United States Chemical Safety and Hazard Investigation Board (CSB) requested information including the incident investigation report and causal factors of the incident, which we submitted to the CSB.

This inquiry is still active with the CSB.

Pipeline Security - In April 2021, the United States Department of Homeland Security’s Transportation Security Administration (TSA) released revised pipeline security guidelines that included broader definitions for the determination of pipeline “critical facilities.” In September 2024, we completed our annual review of our pipeline facilities according to the guidelines.

We do not believe continued compliance with

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safety standards and other requirements applicable to our underground natural gas storage facilities will have a material impact on results of operations, financial position or cash flows.

Pipeline Security - In April 2021, the United States Department of Homeland Security’s Transportation Security Administration (TSA) released revised pipeline security guidelines that included broader definitions for the determination of pipeline “critical facilities.” In January 2026, we completed our 2025 annual review of our pipeline facilities according to the guidelines.

The cost of compliance did not have a material impact on our operations, financial position or cash flows.

In July 2021, the TSA began issuing pipeline security directives to owners and/or operators of critical pipeline systems or facilities.

Pursuant to those directives, our Cybersecurity Implementation Plan was last approved in August 2024, and our Cybersecurity Assessment Plan was last approved in September 2024.

Pursuant to those directives, our Cybersecurity Implementation Plan was last approved in November 2025, and our Cybersecurity Assessment Plan was last approved in September 2025.

While compliance with the security directives requires significant internal and external resources, we do not expect it to have a material impact on our results of operations, financial position or cash flows.

HUMAN CAPITAL

The long-term sustainability of our business is dependent on our continued ability to maintain a highly engaged workforce.

To accomplish this, our business strategy includes attracting, selecting and retaining talent, advancing an inclusive, diverse and engaged culture and developing individuals and leaders.

We conduct employee engagement surveys, typically on an annual basis.

In 2024, the annual employee engagement participation rate increased to 93% compared with 90% in 2022, the last year a survey was conducted.

We did not complete a survey in 2023 as we focused on stabilizing and integrating our employee base following the Magellan Acquisition.

The overall engagement mean increased to the 80th percentile and the ratio of engaged employees to actively disengaged also increased.

All leaders have been asked to discuss the 2024 survey results with their teams and create an engagement plan for 2025.

Training and support resources are available through our learning management system, the Gallup engagement portal and dedicated individuals, engagement champions, within the business.

31, 2024, we had 5,177 employees, which excludes EnLink employees.

Our business strategy includes attracting, selecting and retaining talent, advancing an inclusive, diverse and engaged culture and developing individuals and leaders.

As of December 31, 2025, we had 6,326 employees.

Listed below is a summary of our human capital resources, measures and objectives that are collectively important to our success as an organization.

Values - Our success relies on the skills, experience and dedication of our employees.

We are committed to cultivating an inclusive and dynamic work environment where people can find opportunities to succeed, grow and contribute to the success of the company.

We are committed to cultivating an inclusive and dynamic work environment where people can find opportunities to succeed, grow and contribute to our success.

Our employees work each day to provide safe and reliable services to a wide range of customers in the states where we operate.

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• Excellence:

we hold ourselves and others accountable to a standard of excellence through continuous improvement and teamwork.

we hold ourselves and others accountable to a standard of excellence through collaboration and continuous improvement.

we invest our time, effort and resources to serve each other, our customers and communities.

• Innovation:

we seek to develop creative solutions by leveraging collaboration through ingenuity and technology.

Inclusion and Diversity - Our inclusion and diversity (I&D) strategy is a cross-functional effort that draws upon contributions from employees at all levels of the organization and is focused on enhancing the workplace to attract and retain talent.

we create value by leveraging collaboration, ingenuity and technology.

Employee Engagement, Inclusion and Diversity - Our employee engagement, inclusion and diversity strategy is a cross-functional effort that draws upon contributions from employees at all levels of the organization and is focused on enhancing the workplace to attract and retain talent.

The strategy is guided by a council composed of a diverse group of employees who represent different demographics, work locations, points of view, roles and levels of seniority.

We also have a team within our human resources department that is wholly dedicated to supporting our I&D efforts.

We also have a team within our human resources department that is wholly dedicated to supporting our employee engagement, inclusion and diversity efforts.

We provide support for four employee-led business resource groups (BRGs) that include a Racial/Ethnic Inclusion Resource Group, Veterans Resource Group, Women’s Resource Group and LGBTQ+ Resource Group.

The purpose of these groups is to promote the attraction, development, engagement and retention of members of traditionally underrepresented groups in our industry and workplace in an effort to drive positive business outcomes.

The purpose of these groups is to promote the attraction, development, engagement and retention of talented members of traditionally underrepresented groups in our industry and workplace in an effort to drive positive business outcomes.

A key factor in the success of our BRGs is the active participation by officer-level executive sponsors and allies from outside the BRG’s underrepresented populations.

All employees are invited to become supporters of our BRGs.

We embed I&D concepts into our core leadership development curriculum and sponsor a number of internal programs intended to promote I&D.

We embed employee engagement, inclusion and diversity concepts into our core leadership development curriculum and sponsor a number of internal programs intended to promote employee engagement, inclusion and diversity.

In addition, we seek to give back to the communities where we operate by partnering on initiatives to support underrepresented community members and local charitable organizations.

We conduct employee engagement surveys, typically on an annual basis.

In 2025, the annual employee engagement participation rate increased to 95% compared with 93% in 2024.

The overall engagement mean increased to the 81st percentile and the ratio of engaged employees to actively disengaged also increased.

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Employee Safety - The safety of our employees is critical to our operations and success.

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Eligible employees also have access, at no charge, to an employee assistance program, a medical second opinion service and a health care concierge service to assist with finding in-network providers and billing resolution.

We offer full pay for maternity, paternity or adoption leave of up to 240 hours per qualifying event.

We offer full pay for maternity, paternity or adoption leave of up to six weeks per qualifying event.

We also provide up to $10,000 for reasonable and necessary expenses of a qualifying adoption and/or surrogacy.

Additional benefits available for the welfare of our employees include, among others, life insurance and long-term disability plans, health and dependent care flexible spending accounts, fertility benefits, disease prevention and management programs and full pay while on bereavement, military or personal and family care leave.

We expect that beginning on May 1, 2025, legacy EnLink employees will have access to these ONEOK health and welfare benefits.

On May 1, 2025, legacy EnLink employees received access to these ONEOK health and welfare benefits.

We also provide the opportunity for our employees to help fellow employees through the ONE Trust Fund by contributing donated vacation hours or monetary donations.

The ONE Trust Fund is a nonprofit, charitable organization run entirely by employee volunteers, that serves our employees in times of personal crises due to natural disasters, medical emergencies or other hardships.

The ONE Trust Fund is an independent nonprofit, charitable organization run entirely by employee volunteers, that serves our employees in times of personal crises due to natural disasters, medical emergencies or other hardships.

Further, we provide volunteer opportunities and volunteer grants, as well as $10,000 of charitable giving matching, annually, through the ONEOK Foundation.

Subsequent to the EnLink Acquisition completed on Jan.

31, 2025, we expect legacy EnLink employees to have access to the ONE Trust Fund benefits and can begin making contributions to the fund beginning on May 1, 2025.

Personal and Professional Development - We provide various options to assist with career growth and development.

For employees just entering the workforce who desire to advance their career and continue to learn or for the employees who are interested in developing their skills, we provide education and training in a variety of areas, including leadership, functional and industry-specific topics, professional development and skill-building opportunities.

Our organizational development and I&D teams provide live in-person and virtual classroom training, computer-based self-study and one-on-one coaching that is available to all employees.

For employees just entering the workforce who desire to advance their career and continue to learn or for the employees who are interested in developing their skills, we make available to all employees education and training in a variety of areas, including leadership, functional and industry-specific topics, professional development and skill-building opportunities.

We value education and assist eligible employees with the expense of furthering their education in job-related fields, including up to $5,250 per year in qualifying tuition expenses.

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We use targeted recruitment events, maintain strong relationships with area technical schools, colleges and universities, and we offer compensation benefits and career opportunities that are designed to position us as an employer of choice.

I&D continues to be a priority in recruiting, and we deploy sourcing strategies designed to access talent from groups that are historically underrepresented in our industry and workplace.

Retirement - We maintain a 401(k) Plan for our employees and match 100% of employee contributions up to 6% of eligible compensation each payroll period, subject to applicable tax limits.

We have a legacy defined benefit pension plan covering certain employees and former employees, which closed to new participants in 2005.

In addition, as a result of the Magellan Acquisition, we assumed the pension and postretirement benefit obligations for Magellan employees and former employees.

These obligations are composed of two defined benefit pension plans, including one for non-union employees and one for union employees, as well as a postretirement welfare benefit plan for certain employees.

The pension plan for non-union employees closed to new participants upon the closing of the Magellan Acquisition.

The pension plan for union employees closed to new participants in January 2024.

Employees who do not participate in our defined benefit pension plan are eligible to receive quarterly and annual profit-sharing contributions under our 401(k) Plan.

Effective Jan.

1, 2025, the profit-sharing quarterly contributions increased to 6% from 1% of quarterly eligible compensation.

We will continue to make annual discretionary contributions of up to 2% of eligible compensation.

31, 2024, 96% of eligible employees were contributing to our 401(k) Plan.

For additional information about our retirement benefits, see Note M of the Notes to Consolidated Financial Statements in this Annual Report.

Employee engagement, inclusion and diversity continues to be a priority in recruiting, and we deploy strategies designed to access talent from many sources, skill sets and backgrounds.

Retirement - We maintain the ONEOK 401(k) Plan for our employees and match 100% of employee 401(k) Plan contributions up to 6% of each participant’s eligible compensation, subject to certain conditions and limits.

We maintain three defined benefit pension plans, including the ONEOK Retirement Plan, covering certain legacy ONEOK employees, and the Magellan Pension Plan and the Magellan Pension Plan for USW Employees, each covering certain legacy Magellan employees.

We also make profit-sharing contributions under our 401(k) Plan for employees who do not participate in our defined benefit pension plans.

Effective January 1, 2025, quarterly profit-sharing contributions increased to 6% from 1% of each profit-sharing participant’s eligible compensation during the quarter.

We may also make annual discretionary profit-sharing contributions of up to 2% of eligible compensation.

As of December 31, 2025, 96% of eligible employees were contributing to our 401(k) Plan.

For additional information about our retirement benefits, see Note L of the Notes to Consolidated Financial Statements in this Annual Report.

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INFORMATION ABOUT OUR EXECUTIVE OFFICERS

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Name and Position Age Business Experience in Past Five Years

Edwards 66 2022 to present Board Chair, ONEOK

Board Chair 2007 to 2022 Board Director, ONEOK

Norton II 66 2021 to present President and Chief Executive Officer, ONEOK

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Executive Vice President and Chief Operating Officer 2010 to 2024 President and Chief Executive Officer, Medallion Midstream, LLC

66 2022 to present Senior Vice President, Natural Gas Pipelines, ONEOK

Senior Vice President, Natural Gas Pipelines 2018 to 2022 Senior Vice President, Natural Gas, ONEOK

Spears 46 2022 to present Senior Vice President and Chief Accounting Officer, Finance and Tax, ONEOK

Senior Vice President and Chief Accounting Officer, Finance and Tax 2019 to 2021 Vice President and Chief Accounting Officer, ONEOK

(a) - Charles M.

Kelley has announced his retirement, effective March 2025.

No family relationships exist between any of the executive officers, nor is there any arrangement or understanding between any executive officer and any other person pursuant to which the officer was selected.

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Information contained on our website, or posted on our social media accounts, including any corresponding applications, are not incorporated by reference into this report.

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Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 1. Business