NYSE: OGS

•Safe Operations - We are committed, first and foremost, to pursuing a zero-incident and 100-percent compliance safety culture. We deploy a variety of operational and damage prevention procedures and technologies to monitor, protect, and maintain our natural gas distribution system. Our focus on safety also extends to protecting our information systems from cyber intrusions.

•Capital Investments - A significant portion of our capital spending is focused on the safety, integrity, and reliability of our natural gas distribution system in a way that serves our customers’ energy needs responsibly and sustainably. We invest capital to meet growing customer demand, support economic development, and manage our technology needs.

•Serving Customers - We provide safe, reliable, and affordable energy to meet our customers’ evolving energy needs. We manage our resources effectively and leverage technology solutions to enhance operational efficiency.

•Delivering Foundational Energy - Our assets are essential to our customers and the integrated energy system. Natural gas and its applications as a foundational energy source play a crucial role in meeting growing energy needs and complementing renewables and other energy sources.

REGULATORY OVERVIEW

We are subject to the regulation and oversight of the state and local regulatory authorities of the territories in which we operate. Rates and charges for natural gas distribution services are established by the OCC for Oklahoma Natural Gas and by the KCC for Kansas Gas Service. Rates and charges in the incorporated cities of our service areas in Texas are established by those cities, which have primary jurisdiction. Rates and charges in the unincorporated areas of our service territory in Texas are established by the RRC. All appellate matters in Texas are subject to regulatory oversight by the RRC. These regulatory authorities have the responsibility of ensuring that the utilities under their jurisdiction provide safe and reliable service at a reasonable cost, while providing utilities the opportunity to earn a fair and reasonable return on their investments.

Generally, our rates and charges are established in rate case proceedings. Regulatory authorities may also approve mechanisms that allow for adjustments between rate cases for investments made or specific costs incurred. Due to the nature of the regulatory process, there is an inherent lag between the time that we make investments or incur additional costs and the setting of new rates and/or charges to recover those investments or costs. Additionally, we are not allowed recovery of certain costs we incur.

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In each jurisdiction in which we operate, changes in customer usage are considered in the periodic redesign of our rates.

The following provides additional detail on the regulatory mechanisms in the jurisdictions we serve.

Oklahoma - Oklahoma Natural Gas currently operates under a PBRC mechanism, which provides for streamlined annual rate reviews between rate cases to adjust rates for incremental capital investment and changes in revenue and allowed expenses. Under this mechanism, we have an authorized ROE of 9.4 percent, with a 100 basis point dead-band of 8.9 to 9.9 percent. If our achieved ROE is below 8.9 percent, our base rates are increased upon OCC approval to an amount necessary to restore the ROE to 9.4 percent. If our achieved ROE exceeds 9.9 percent, the portion of the earnings that exceeds 9.9 percent is shared with our customers, who receive the benefit of 75 percent of those earnings. We retain the benefit of the remaining 25 percent. Oklahoma Natural Gas is required to make filings pursuant to the PBRC mechanism for the 12 months ended December 31 for each of the years 2021 through 2025. Oklahoma Natural Gas is also required to file a rate case on or before June 30, 2027, based on a test year ending December 31, 2026.

Kansas - Kansas Gas Service files periodic rate cases with the KCC. Between rate cases, Kansas Gas Service adjusts rates through provisions of the GSRS statute. The GSRS statute allows Kansas Gas Service to file for a rate adjustment providing a recovery of and return on qualifying infrastructure investments incurred between rate case filings, including safety-related investments to replace, upgrade or modernize obsolete facilities, as well as projects that enhance the integrity of pipeline system components or extend the useful life of such assets. Eligible investments also include expenditures for relocations and physical and cyber security. Filings cannot occur more often than once every 12 months and the rate adjustment cannot increase the monthly charge by more than $0.80 per residential customer per month compared with the most recent GSRS filing. Rate adjustments reflected in the GSRS surcharge may only be collected for 60 months before Kansas Gas Service is required to file a rate case or cease collection of the surcharge. A full rate case may be filed at shorter intervals if desired by either Kansas Gas Service or the KCC.

Texas - Texas Gas Service files periodic rate cases with cities we serve and the RRC. Between rate cases, Texas Gas Service can adjust rates through annual filings pursuant to the GRIP statute. In February 2026, Texas Gas Service’s customers were aggregated in a single statewide service area. Prior to February 2026, Texas Gas Service’s customers were aggregated in three services areas.

Annual filings under the GRIP statute allow Texas Gas Service to recover depreciation, taxes, and a return on the annual net increase in investment. After the fifth anniversary of the effective date of the rate schedules from the first GRIP filing, Texas Gas Service is required to file a full rate case. A full rate case may be filed at shorter intervals if desired by either Texas Gas Service or the applicable regulator. In 2025, Texas Gas Service made annual GRIP filings in all of its previously designated service areas.

Weather normalization - All of our service areas utilize weather normalization mechanisms. These mechanisms are designed to reduce the delivery charge component of customers’ bills for the additional volumes used when actual HDDs exceed normalized HDDs and to increase the delivery charge component of customers’ bills for the reduction in volumes used when actual HDDs are less than normal HDDs. Normal HDDs are established through rate proceedings in each of our jurisdictions.

The following tables provide additional detail on our rate structures and the regulatory mechanisms in each of our jurisdictions:

DivisionJurisdiction
Effective Date of Last Action(1)
Rate Base (millions)Pre-Tax Rate of ReturnEquity RatioROE

Oklahoma Natural Gas (2)
OklahomaJune 2025$2,4538.94%59%9.40%

Kansas Gas Service (3)
KansasAugust 2025$1,4688.97%
N/A
9.60%

Texas Gas Service (4)
TexasJanuary 2026$1,8879.22%60%9.80%

DivisionJurisdictionInterim Rate Adjustment MechanismInterim Capital RecoveryWNAWNA Effective DatesEnergy Efficiency / Conservation Program

Oklahoma Natural GasOklahomaPBRCYesYesNovember - AprilYes

Kansas Gas ServiceKansasGSRSYesYesJanuary - DecemberNo

Texas Gas ServiceTexasGRIPYesYesSeptember - MayNo

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DivisionJurisdiction
Purchased Gas Adjustment(5)

Bad Debt Recovery(6)

Expense Trackers(7)

Oklahoma Natural GasOklahomaYesYesN/A

Kansas Gas Service (3)
KansasYesYesYes

Texas Gas ServiceTexasYesYesYes

(1)Effective date of last approved rate case or interim filing.

(2)The rate base, authorized ROE, authorized debt/equity ratio, and authorized return on equity presented in this table are those from the most recent approved regulatory filing for Oklahoma Natural Gas.

(3)Kansas Gas Service’s most recent rate case, approved in November 2024, settled without a determination of rate base, ROE, authorized debt/equity ratio, and authorized return on equity. This reflects Kansas Gas Service’s estimate of rate base from that rate case adjusted for approved GSRS filings and of the ROE embedded in the pre-tax carrying charge utilized in its GSRS filing.

(4)The authorized ROE, debt/equity ratio, and return on equity presented in this table are those from the most recently approved rate case for Texas Gas Service, which settled without a determination of rate base. The rate base presented reflects Texas Gas Service’s estimate of rate base from that rate case.

(5)Our purchased gas adjustment mechanisms allow recovery of expenses the Company incurs to purchase, transport, and store natural gas for our customers. These costs are passed on to customers without markup.

(6)We recover the gas cost portion of bad debts through our various purchased gas adjustment mechanisms.

(7)Expense trackers include pension and other postemployment benefits costs for Kansas Gas Service and Texas Gas Service, ad-valorem taxes in Kansas, and pipeline integrity testing expenses in Texas.

Our natural gas sales include fixed and variable charges related to the delivery of natural gas and gas costs that are passed through to our customers in accordance with our cost of natural gas regulatory mechanisms. Fixed charges reflect the portion of our natural gas sales attributable to the monthly fixed customer charge component of our rates, which does not fluctuate based on customer usage in each period. Variable charges reflect the portion of our natural gas sales that fluctuate with the volumes delivered and billed and the effects of weather normalization.

For the year ended December 31, 2025, approximately 91 percent, 52 percent, and 66 percent of our revenues from sales customers, excluding the cost of natural gas, were recovered from fixed charges for Oklahoma Natural Gas, Kansas Gas Service, and Texas Gas Service, respectively.

MARKET CONDITIONS AND SEASONALITY

Supply - We purchased 165 Bcf and 149 Bcf of natural gas supply in 2025 and 2024, respectively. Our natural gas supply portfolio consists of contracts with varying terms from a diverse group of suppliers. We award these contracts through competitive-bidding processes to ensure reliable and competitively priced natural gas supply. We acquire our natural gas supply from natural gas processors, marketers, and producers.

An objective of our supply-sourcing strategy is to provide value to our customers through reliable, competitively priced, and flexible natural gas supply and transportation from multiple production areas and suppliers. This strategy is designed to mitigate the impact on our supply from physical interruptions, financial difficulties of a single supplier, natural disasters, and other unforeseen force majeure events, as well as to ensure that adequate supply is available to meet the variations of customer demand.

We do not anticipate problems with securing natural gas supply to satisfy customer demand; however, if supply shortages were to occur, we have curtailment provisions in our tariffs that allow us to reduce or discontinue natural gas service to large industrial users and to request that residential and commercial customers reduce their natural gas requirements to an amount essential for public health and safety. In addition, during times of critical supply disruptions, curtailments of deliveries to customers with firm contracts may be made in accordance with guidelines established by appropriate federal, state, and local regulatory agencies.

Natural gas supply requirements for our sales customers are impacted by weather and economic conditions. Our customers’ usage may also change in response to a variety of factors, including:

•the occurrence of a significant disruption in natural gas supplies, either by itself, or accompanied by higher or lower natural gas prices;

•the availability of more energy-efficient construction methods or home improvements such as installation or replacement of insulated doors and windows, additional or energy efficient insulation, and installation or replacement of existing appliances with more efficient appliances; and

•fuel switching from natural gas to other energy alternatives.

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In managing our natural gas supply portfolios, we partially mitigate price volatility for our customers using a combination of natural gas in storage, fixed-price natural gas contracts, and financial derivatives. We have natural gas financial hedging programs that have been authorized by the OCC, KCC, and in the incorporated municipalities in Texas. We do not utilize financial derivatives for speculative purposes, nor do we have trading operations associated with our business.

As of December 31, 2025, we had 60.8 Bcf of natural gas storage capacity under contract with remaining terms ranging from one to ten years and maximum allowable daily withdrawal capacity of approximately 1.8 Bcf. This storage capacity allows us to purchase natural gas during the off-peak season and store it for use in the winter periods. This storage is also needed to support the reliability of gas deliveries during peak demands for natural gas. Approximately 35 percent of our winter natural gas supply needs for our sales customers is expected to be supplied from storage.

Demand - See discussions below under Seasonality and Competition for factors affecting demand for our services.

Seasonality - Natural gas sales to residential and commercial customers are seasonal, as a substantial portion of their natural gas requirements are for heating. Accordingly, the volume of natural gas sales is normally higher during the months of November through March than in other months of the year. The impact on our natural gas sales resulting from weather temperatures that are above or below normal is offset partially through our WNA mechanisms. See the tables above under Regulatory Overview for additional information.

Competition - We encounter competition based on customers’ preference for natural gas, compared with other energy alternatives and their comparative prices. We compete primarily to supply energy for space and water heating, cooking, and clothes drying. Significant energy usage competition occurs between natural gas and electricity in the residential and small commercial markets. Customers and builders typically make the decision on the type of equipment, and therefore the energy source, at initial installation, generally locking in the chosen energy source for the life of the equipment. Changes in the competitive position of natural gas relative to electricity and other energy alternatives have the potential to cause a decline in consumption of natural gas or in the number of natural gas customers. In Texas, we are also subject to competition from other local distribution companies.

We are subject to competition from other pipelines for our large industrial and commercial customers. Under our transportation tariffs, qualifying industrial and commercial customers are able to purchase their natural gas supply from the provider of their choice and contract with us to transport it for a fee. A portion of the transportation services that we provide are at negotiated rates that are below the maximum approved transportation tariff rates. Reduced-rate transportation service may be negotiated when a competitive pipeline is in close proximity or another viable energy option is available to the customer.

ENVIRONMENTAL AND SAFETY MATTERS

See Note 15 of the Notes to Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations in this Annual Report for information regarding environmental and safety matters.

HUMAN CAPITAL

We intentionally cultivate an inclusive culture that values diverse perspectives. This approach fosters an engaged, high-performing workforce and creates an environment that attracts top talent.

Employment - We employed approximately 4,000 people on February 1, 2026, including approximately 700 people at Kansas Gas Service who are subject to collective bargaining agreements. The following table sets forth our contracts with collective bargaining units at February 1, 2026:

UnionApproximate EmployeesContract Expires

The United Steelworkers400May 31, 2028

International Brotherhood of Electrical Workers 300June 30, 2027

We recognize that employees are a key stakeholder group for the success of our business. Therefore, we perform an annual survey to monitor and assess employee engagement.

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Workplace Health and Safety - Safety is our number one core value. We are committed to pursuing a zero-incident safety culture, which can reduce risk, enhance productivity, and build a strong reputation in the communities in which we operate. Our success is reliant on training and development, performance management, and shared responsibility that focuses on engagement and ensures our employees know what is expected to keep themselves, their co-workers, our customers, and communities safe. We have implemented and track operational safety measures focused on the importance of personal injury prevention, reducing the severity of injuries, safe driving, and public safety. The following table sets forth our performance for the periods indicated:

Year Ended December 31,

Operational measures focused on safety202520242023

TRIR1.271.331.09

DART0.180.150.16

PVIR1.601.561.82

ERT66.3%65.6%64.8%

TRIR, DART, and PVIR are personal safety metrics tracked by the American Gas Association. We regularly rank in the top quartile for similar-sized local distribution companies for these metrics.

We are committed to a supportive culture of physical, financial, emotional, and social wellness for employees. We provide health and wellness programs to support and inspire our employees to make healthy personal and professional lifestyle choices.

Inclusion and Diversity - Our core values include inclusion and diversity, and we believe in creating equal opportunities to recognize the value and voice of every employee.

We have an Inclusion and Diversity Council, which is chaired by our Chief Executive Officer, that includes both permanent members and rotating members from various functional areas, backgrounds, and experiences. The Inclusion and Diversity Council provides governance and guidance for sharing our vision of an inclusive and diverse workforce. In addition, we have employee-led resource groups, which are open to all employees, to provide community and support to our employees.

The Company is committed to providing equal opportunity to all employees and applicants and proactively reviews its policies and programs for compliance with all applicable laws, regulations, and executive orders. None of the Company’s Inclusion and Diversity efforts include quotas or preferences based upon an individual’s membership in a particular constituency, and participation in all Inclusion and Diversity activities is voluntary and open to all employees.

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INFORMATION ABOUT OUR EXECUTIVE OFFICERS

All executive officers are elected annually by our Board of Directors and each serves until such person resigns, is removed, or is otherwise disqualified to serve or until such officer’s successor is duly elected. Our executive officers listed below include the officers who have been designated by our Board of Directors as our Section 16 officers.

Name Age*Business Experience in Past Five Years

Robert S. McAnnally622021 to presentPresident, Chief Executive Officer and Director

2020 to 2021Senior Vice President and Chief Operating Officer

Christopher P. Sighinolfi422024 to presentSenior Vice President and Chief Financial Officer

2022 to 2024Vice President, Corporate Development and Investor Relations

2021 to 2022Vice President, Corporate Development

Curtis L. Dinan582021 to presentSenior Vice President and Chief Operating Officer

2020 to 2021Senior Vice President and Chief Commercial Officer

Regina L. Gregory552025 to presentSenior Vice President, General Counsel and Assistant Secretary

2020 to 2024Executive Vice President, General Counsel and Corporate Secretary, Targa Resources Corp.

2018 to 2020Vice President and Assistant General Counsel, Targa Resources Corp.

Mark A. Bender612015 to presentSenior Vice President, Administration and Chief Information Officer

Angela E. Kouplen512023 to presentSenior Vice President and Chief Human Resources Officer

2022 to 2023Vice President of Administration and Chief Information Officer, the University of Tulsa

2021 to 2022Vice President and Chief Information Officer, the University of Tulsa

2016 to 2021Senior Vice President of Administration and Chief Information Officer, WPX Energy

W. Kent Shortridge592022 to presentSenior Vice President, Operations and Customer Service

2018 to 2022Managing Vice President, Operations

Brian F. Brumfield582022 to presentVice President, Chief Accounting Officer and Controller

2017 to 2022Controller, Tucson Electric Power/UNS Energy

* As of January 1, 2026

No family relationship exists 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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