NYSE: NI

Our goal is to develop strategies that (i) support long-term infrastructure investment and safety programs to better serve our customers, (ii) align our tariff structures with our cost structure, and (iii) drive value and enable growth in an evolving energy ecosystem. These strategies focus on improving safety and reliability, enhancing customer experience, pursuing regulatory and legislative initiatives to increase accessibility for customers currently not on our gas and electric service, ensuring customer affordability and reducing emissions while generating sustainable returns.

We remain committed to the advancement of our SMS for the safety of our customers, communities and employees. Our SMS is the established operating model within NiSource. NiSource continues to maintain its certification to the American Petroleum Institute Recommended Practice 1173, which serves as the guiding practice for our SMS. In 2025, NiSource successfully maintained its ISO 55001 Asset Management certifications through LRQA, a global leader in engineering and technology services. These certifications reaffirm our unwavering commitment to safety for our employees and partners, customers, and systems and highlight our continued dedication to operational excellence and the integrity of our SMS.

NiSource has two reportable segments: Columbia Operations and NIPSCO Operations. The remainder of our operations, which are not significant enough on a stand-alone basis to warrant treatment as an operating segment, consist of our centralized corporate activities and are primarily comprised of interest expense on holding company debt and unallocated corporate costs and activities, as well as new business development costs associated with GenCo. The following is a summary of the business for each reporting segment. Refer to Part II. Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and Note 21, "Business Segment Information," in the Notes to Consolidated Financial Statements for additional information related to each segment.

Columbia Operations

Columbia Operations provides natural gas to approximately 2.4 million residential, commercial and industrial customers in Ohio, Pennsylvania, Virginia, Kentucky, and Maryland. We operate approximately 37,300 miles of distribution main pipeline plus the associated individual customer service lines and 310 miles of transmission main pipeline located in our service areas described above. Throughout our service areas we also have gate stations and other operations support facilities. See below for information on our owned storage facilities. There were no significant disruptions to our system or facilities during 2025.

ITEM 1. BUSINESS

Facility Name Location Type Storage Capacity (MCF)

Eagle Cove Propane
Petersburg, VA
Propane Gas 863

South Wales Propane Jeffersonton, VA Propane Gas 863

Portsmouth Propane-Air Portsmouth, VA Propane-Air Gas 17,300

Total Capacity 19,026

Competition. Due to open access and the deregulation of natural gas supplies, our LDC customers can purchase gas directly from producers and marketers in an open, competitive market. Certain of our subsidiaries are involved in programs that provide our residential and commercial customers the opportunity to purchase their natural gas requirements from third parties and use our subsidiaries for transportation services. As of December 31, 2025, 34.9% of our residential customers and 41.1% of our commercial customers participated in such programs.

We compete with (i) investor-owned, municipal, and cooperative electric utilities throughout our service areas, (ii) other regulated and unregulated natural gas intra and interstate pipelines and (iii) other alternate fuels, such as propane and fuel oil. We continue to be a well-positioned competitor in the energy markets in which we operate due to customer preference for natural gas.

Additionally, we are subject to seasonal fluctuations in sales. Revenues from our gas distribution operations are more significant during the heating season, which is from October through May. Please refer to Part II, Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations - Results and Discussion of Operations - Columbia Operations," for additional information.

NIPSCO Operations

NIPSCO Operations includes the results of NIPSCO Holdings I and its majority-owned subsidiaries, including NIPSCO, which has fully regulated gas and electric operations in northern Indiana.

NIPSCO Gas

NIPSCO Gas distributes natural gas to approximately 0.9 million customers in northern Indiana. We operate approximately 18,100 miles of distribution main pipeline plus the associated individual customer service lines and 720 miles of transmission main pipeline located in our northern Indiana service areas. Throughout northern Indiana, we also have gate stations and other operations support facilities. See below for information on our owned storage facilities. There were no significant disruptions to our system or facilities during 2025.

Facility Name

Location

Type

Storage Capacity (MCF)

Royal Center Underground Storage

Royal Center, IN

Natural Gas
7,240,000

Rolling Prairie LNG

Rolling Prairie, IN

Liquified Natural Gas
4,000,000

Total Capacities
11,240,000

Competition. Similar to the Columbia Operations segment, NIPSCO Gas operates in an open and competitive market which allows retail customers to purchase gas directly from producers and marketers. As of December 31, 2025, 6.8% of our residential customers and 18.5% of our commercial customers participated in such programs.

We compete with (i) investor-owned, municipal, and cooperative electric utilities throughout our northern Indiana service area, (ii) other regulated and unregulated natural gas intra and interstate pipelines and (iii) other alternate fuels, such as propane and fuel oil. We continue to be a well-positioned competitor in the northern Indiana market due to customer preference for natural gas.

Additionally, we are subject to seasonal fluctuations in sales. Revenues from our gas distribution operations are more significant during the heating season, which is from October through May. Please refer to Part II, Item 7, "Management's

ITEM 1. BUSINESS

Discussion and Analysis of Financial Condition and Results of Operations - Results and Discussion of Operations - NIPSCO Operations," for additional information.

NIPSCO Electric

We generate, transmit and distribute electricity to approximately 0.5 million customers in 20 counties in the northern part of Indiana. We also engage in wholesale electric and transmission transactions, and enter into customized agreements to provide electric service to data center customers. Our transmission system, has voltages from 69,000 to 765,000 volts, and consists of approximately 3,000 circuit miles. We are interconnected with eight neighboring electric utilities. We operate 65 transmission and 240 distribution substations, and own approximately 312,500 poles. We own and operate generation assets as well as source power through PPAs. We currently have eight renewable generation facilities in service, three of which were placed into service in 2025. As of December 31, 2025, we also have multiple PPAs that provide approximately 1,200 MW of capacity, with contracts expiring between 2038 and 2045. We also operate two hydroelectric generation facilities, a CCGT, and two coal generation facilities.

In December 2025, before the planned retirement of the R.M. Schahfer coal facility, the U.S. Secretary of Energy issued an emergency order under section 202(c) of the Federal Power Act requiring R.M. Schahfer to continue operating for 90 days, through March 23, 2026. The order stated that continued operation of R.M. Schahfer was required to meet an energy emergency across MISO’s North and Central regions and authorizes NIPSCO to obtain cost recovery pursuant to 16 U.S.C. § 824a(c). For additional information, see Part II, Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations - "Results and Discussion of Operations - NIPSCO Operations," and Part I, Item 1A. "Risk Factors." The Michigan City coal facility is scheduled to be retired by the end of 2028.

We had forced outages during 2025, none of which had material impacts to our operations. See below for information on our owned generating facilities:

Facility Name Location Fuel Type
Generating Capacity (MW)(1)

R.M. Schahfer Wheatfield, IN Steam - Coal 722

Michigan City Michigan City, IN Steam - Coal 455

Sugar Creek
West Terre Haute, IN CCGT 665

R.M. Schahfer Wheatfield, IN Natural Gas 155

Oakdale Carroll County, IN Hydro 9

Norway White County, IN Hydro 7

Rosewater(2)
White County, IN Wind 102

Indiana Crossroads Wind(2)
White County, IN Wind 302

Dunns Bridge I(2)

Jasper County, IN

Solar
265

Indiana Crossroads Solar(2)
White County, IN
Solar
200

Cavalry Solar and Storage(3)

White County, IN

Solar and Storage
200

Dunns Bridge II(3)

Jasper County, IN

Solar and Storage
435

Fairbanks Solar

Sullivan County, IN

Solar
250

Gibson Solar

Gibson County, IN

Solar
200

Total MW Capacity 3,967

(1)Represents current net generating capability of each fossil fuel and hydro generating facility. Nameplate capacity is listed for wind and solar generating facilities.

(2)NIPSCO is the managing partner of these JVs. Refer to Note 4, "Noncontrolling Interests," in the Notes to Consolidated Financial Statements for more information.

(3)Cavalry Solar and Storage has installed battery storage capacity of 45MW over a four-hour duration. Dunns Bridge II has installed battery storage capacity of 56MW over a four-hour duration.

ITEM 1. BUSINESS

NIPSCO's 2024 Integrated Resource Plan ("2024 Plan") was submitted to the IURC in December 2024. The 2024 Plan informs future generation investments required to ensure reliability for NIPSCO's customers and incorporated factors such as anticipated load growth from data centers and other economic development opportunities, new EPA emissions rules, and evolving MISO resource accreditation rules. The 2024 Plan maintains the retirement decisions and capacity additions identified in the 2018 and 2021 Integrated Resource Plans and calls for additional generation resources through 2029 to support capacity requirements, along with new gas-fired resources and other capacity resources to support new data center load. In this regard, we executed the ADS Contract in September 2025. As we continue to evaluate additional agreements with data center customers, future integrated resource plans will take this into consideration. Refer to Part II, Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations” for further discussion of these plans.

NIPSCO participates in the MISO transmission service and wholesale energy market. MISO is a nonprofit organization created in compliance with FERC regulations to improve the flow of electricity in the regional marketplace and to enhance electric reliability. Additionally, MISO is responsible for managing energy markets, transmission constraints and the day-ahead, real-time, Financial Transmission Rights and ancillary markets. NIPSCO has transferred functional control of its electric transmission assets to MISO, and transmission service for NIPSCO occurs under the MISO Open Access Transmission Tariff. NIPSCO generating units are dispatched by MISO which takes into account economics, reliability of the MISO system and unit availability. During the year ended December 31, 2025, NIPSCO generating units, inclusive of its owned renewable generation facilities, were dispatched to meet 55.4% of its overall system load, and the remainder of the overall system load was procured through PPAs and the MISO market.

Competition. Our NIPSCO Electric utility generally has exclusive service areas under Indiana regulations and retail electric customers in Indiana do not have the ability to choose their electric supplier. NIPSCO faces non-utility competition from other energy sources, such as self-generation by large industrial customers and other distributed energy sources. With respect to data center customers, we face competition from utilities and other energy sources across the United States and abroad. Data center customers consider numerous factors in selecting sites for their operations, including, but not limited to, local weather conditions and patterns, cost of land, local political environment, anticipated ease of zoning and permitting, applicable taxes, and the ability of utilities or power providers to deliver electricity quickly and at scale.

Our NIPSCO Operations are subject to seasonal fluctuations in sales. Revenues from electric operations are more significant during the cooling season, which is primarily from June through September. Please refer to Part II, Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations - Results and Discussion of Operations - NIPSCO Operations," for additional information.

Regulatory

The regulatory landscape, at both the state and federal levels, continues to evolve, impacting the operations and financial results of our operating companies. Management continually seeks new ways to be more competitive and efficient in this environment, while keeping service and affordability for customers at the forefront. We believe we are, in all material respects, in compliance with applicable laws and regulations at both the state and federal level and do not expect future compliance requirements to have a material impact on our capital expenditures, earnings, or competitive position. While we continue to monitor existing and pending laws and regulations, the impact of regulatory changes cannot be predicted with certainty.

ITEM 1. BUSINESS

Rate Case Actions. The following table describes current rate case actions as applicable in each of our jurisdictions. See "Cost Recovery and Trackers" below for further detail on trackers.

(in millions)

Company Approved ROE Requested Incremental Revenue Approved Incremental Revenue
Filing Date
Rates

Effective

Approved Rates Cases

Columbia of Pennsylvania
10.00 % $ 110.4 $ 55.6 March 20, 2025 January 2026

Columbia of Maryland
9.80 % $ 10.7 $ 7.8 September 24, 2024 April 2025

Columbia of Kentucky
9.75 % $ 23.8 $ 14.3 May 16, 2024 January 2025

Columbia of Virginia(1)
9.75 % $ 37.2 $ 28.2 April 29, 2024 October 2024

Columbia of Ohio 9.60 % $ 221.4 $ 68.3 June 30, 2021 March 2023

NIPSCO - Gas(2)
9.75 % $ 161.9 $ 120.9 October 25, 2023 August 2024

NIPSCO - Electric(3)
9.75 % $ 368.7 $ 257.0 September 12, 2024 July 2025

(1)The approved rate case resulted in a black box settlement, representing a settlement to a specific revenue increase but not a specified ROE. The settlement provides use of a 9.75% ROE for future SAVE filings.

(2)New rates were implemented in 2 steps, with implementation of Step 1 rates effective in August 2024 and Step 2 rates effective in February 2025.

(3)New rates were implemented in multiple steps, with implementation of Step 1 rates in July 2025 and Step 2 rates effective by March 2026.

FERC. Our service company and operating companies are subject to varying degrees of regulation by the FERC. NiSource Corporate Services files a FERC Form 60 annual report with its financial information as a FERC jurisdictional centralized service company. NiSource also files an annual FERC Form 61 which contains a narrative description of the service company's functions during the prior calendar year.

As natural gas LDCs, Columbia of Maryland, Columbia of Ohio, Columbia of Pennsylvania, Columbia of Virginia, Columbia of Kentucky and NIPSCO Gas have limited jurisdictional certificates to transport gas in their respective service territories and into interstate commerce.

As an electric company, NIPSCO Electric has Market Based Rate authority and is a Transmission Owner subject to FERC jurisdiction. NIPSCO files the following reports annually:

•FERC Form 1, which is a comprehensive financial and operating report,

•FERC Form 566, which is a list of its 20 largest purchases of electricity over the past three years,

•FERC Form 715, which is its Annual Transmission Planning and Evaluation Report and the base case power flow data from the Eastern Interconnection Reliability Assessment Group Multiregional Modeling Working Group, which is used by NIPSCO for transmission planning and,

•FERC Form 730, which is NIPSCO’s Report of Transmission Investment Activity.

As a Transmission Owner subject to the MISO Transmission Owners Agreement and Tariff, NIPSCO has various FERC jurisdictional obligations such as maintaining its Attachment O formula rates and corresponding protocols. NIPSCO also has FERC approvals to make affiliate transactions between itself and various JVs. NIPSCO’s officers, on the electric side, are also subject to FERC’s interlocking directorate rules and reporting requirements.

Regulatory Framework. The gas distribution activities of our Columbia and NIPSCO Operations have pursued non-traditional revenue sources within the evolving natural gas marketplace. These efforts include (i) gas supply cost incentive mechanisms for service to their core markets, and (ii) the sale of on-system services in the companies’ service territories. The on-system services are offered by us to customers and include products such as the transportation and balancing of gas on the gas distribution operations utility's system. The incentive mechanisms give the gas distribution operations utilities an opportunity to share in the savings created from such situations as gas purchases made below an agreed upon benchmark price and the remarketing of unused pipeline capacity to reduce overall pipeline costs.

ITEM 1. BUSINESS

We recognize that energy efficiency reduces emissions, conserves natural resources and saves our customers money. Our gas distribution companies offer programs such as energy efficiency upgrades, home checkups and weatherization services. The increased efficiency of natural gas appliances and improvements in home building codes and standards contribute to a long-term trend of declining average use per customer. While we are looking to expand offerings so the energy efficiency programs can benefit as many customers as possible, our gas distribution operations utilities have pursued changes in rate design to more effectively match recoveries with costs incurred. Columbia of Ohio has adopted a straight fixed variable rate design for residential and small commercial customers that closely links the recovery of fixed costs with fixed charges. Columbia of Maryland and Columbia of Virginia have regulatory approval for weather and revenue normalization adjustments for certain customer classes, which adjust monthly revenues that exceed or fall short of approved levels. Columbia of Pennsylvania continues to operate its pilot residential weather normalization adjustment and also has a fixed customer charge. This weather normalization adjustment only adjusts revenues when actual weather compared to normal varies by more than 5%. Columbia of Kentucky incorporates a weather normalization adjustment for certain customer classes and also has a fixed customer charge. NIPSCO Gas has also received approval and implemented a weather normalization adjustment for certain of its customer classes. NIPSCO Gas and Electric include a fixed customer charge for residential and small commercial and industrial customer classes.

While increased efficiency of electric appliances and improvements in home building codes and standards have similarly impacted the average use per electric customer in recent years, NIPSCO expects future growth in per customer usage as a result of increasing electric applications, such as electric vehicles. These ongoing changes in use of electricity will likely lead to development of innovative rate designs, and NIPSCO will continue efforts to design rates that increase the certainty of recovery of fixed costs.

Cost Recovery and Trackers. Comparability of our operating results is impacted by regulatory trackers that allow for the recovery in rates of certain costs. Certain approved regulatory tracker mechanisms allow for abbreviated regulatory proceedings in order for the operating companies to quickly implement revised rates and recover associated costs.

A portion of the NIPSCO Operations' and Columbia Operations' gas distribution revenue is related to the recovery of gas costs through GCA's, the review of which occurs through standard regulatory proceedings. All states in our operating area require periodic review of actual gas procurement activity to determine prudence and confirm the recovery of prudently incurred energy commodity costs supplied to customers.

A portion of the NIPSCO Operations' revenue is related to the recovery of fuel costs to generate power and the fuel costs related to purchased power. These costs are recovered through a FAC, which is updated quarterly to reflect actual costs incurred to supply electricity to customers.

Political Action

The NiSource Political Action Committee ("NiPAC") provides our employees a voice in the political process. NiPAC is a voluntary, employee driven, and employee funded political action committee and makes bipartisan political contributions to local, state and federal candidates, where permitted and in accordance with established guidelines. Consistent with our commitments and our approach to engagement, the NiPAC leadership committee members evaluate candidates for support on issues important to our business.

Environmental and Safety Matters

PHMSA Legislation and Regulations

To fulfill our vision of being a trusted energy provider, we follow safety practices required by regulations as we implement our SMS. Our SMS serves as the framework to identify and reduce risks and ensure consistent safety processes, procedures and operations across the organization.

As directed by law in the Protecting Our Infrastructure of Pipelines and Enhancing Safety Act of 2020, PHMSA has proposed and revised various pipeline safety regulations focused on public safety, environmental hazard mitigation, leak detection, methane emissions reduction, and enhanced safeguards for low-pressure distribution systems. Proposed revisions included requirements to detect and repair more leaks, increase survey frequency, and incorporate additional protections to prevent over-pressurization. A final leak detection and repair rule was withdrawn from publication in the Federal Register in January 2025 and the Safety of Gas Distribution Pipelines rulemaking did not progress in 2025.

ITEM 1. BUSINESS

We continue to evaluate and monitor PHMSA-related legislation and regulations but cannot predict the impact of changing pipeline safety laws and regulations on our business at this time.

Environmental and Climate Change Issues

In March 2025, the EPA announced it will undertake 31 deregulatory actions to advance the administration’s policy priorities as directed by various executive orders. These actions will address multiple existing water, waste, air and climate regulations including, but not limited to, GHG and CCR rules. In July 2025, the EPA proposed rescinding the 2009 Endangerment Finding, the scientific and legal foundation for federal GHG regulations under the Clean Air Act. Additionally, in November 2025, the EPA proposed a rule to extend the compliance deadline for owners and operators to complete closure of their unlined CCR surface impoundments larger than 40 acres from October 2028 to October 2031. On February 6, 2026, the EPA issued a final rule extending compliance deadlines for several provisions of the Legacy CCR Rule. NiSource will continue to monitor these matters and assess the impacts to our business as regulations are proposed and finalized, or as otherwise required by law.

Physical Climate Risks. Increased frequency of severe and extreme weather events associated with climate change could materially impact our facilities, energy sales, and results of operations. We are unable to predict these events. However, we perform assessments of physical risk, including physical climate risk, to our business. More extreme and volatile temperatures, increased storm intensity and flooding, and more volatile precipitation leading to changes in lake and river levels are among the weather events that are most likely to impact our business. Efforts to mitigate these physical risks continue to be implemented.

Transition Climate Risks and Opportunities. We actively engage with and monitor the impact that proposed legislative and regulatory programs related to GHG emissions, at both the federal and state levels, would have on our business. Refer to