NISOURCE INC. - Annual Report: 2011 (Form 10-K)

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2011

OR

OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from              to             

Commission file number 001-16189

NiSource Inc.

(Exact name of registrant as specified in its charter)

(877) 647-5990

(Registrant’s telephone number, including area code)

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

Securities registered pursuant to Section 12(g) of the Act:     None

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

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

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes þ   No ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

Yes þ   No ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.   þ

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definition of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12-b-2 of the Exchange Act.

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

The aggregate market value of Common Stock (based upon the June 30, 2011, closing price of $20.25 on the New York Stock Exchange) held by non-affiliates was approximately $5,661,012,618.

There were 282,180,170 shares of Common Stock, $0.01 Par Value outstanding as of January 31, 2012.

Documents Incorporated by Reference

Part III of this report incorporates by reference specific portions of the Registrant’s Notice of Annual Meeting and Proxy Statement relating to the Annual Meeting of Stockholders to be held on May 15, 2012.

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CONTENTS

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DEFINED TERMS

The following is a list of abbreviations or acronyms that are used in this report:

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DEFINED TERMS

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DEFINED TERMS

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ITEM 1. BUSINESS

NISOURCE INC.

NiSource (the “Company”) is an energy holding company whose subsidiaries provide natural gas, electricity and other products and services to approximately 3.8 million customers located within a corridor that runs from the Gulf Coast through the Midwest to New England. NiSource is the successor to an Indiana corporation organized in 1987 under the name of NIPSCO Industries, Inc., which changed its name to NiSource on April 14, 1999.

NiSource is one of the nation’s largest natural gas distribution companies, as measured by number of customers. NiSource’s principal subsidiaries include Columbia, a vertically-integrated natural gas distribution, transmission and storage holding company whose subsidiaries provide service to customers in the Midwest, the Mid-Atlantic and the Northeast; Northern Indiana, a vertically-integrated gas and electric company providing service to customers in northern Indiana; and Columbia of Massachusetts, a natural gas distribution company serving customers in Massachusetts. NiSource derives substantially all of its revenues and earnings from the operating results of its thirteen direct subsidiaries.

NiSource’s business segments are: Gas Distribution Operations; Gas Transmission and Storage Operations; and Electric Operations. Following is a summary of the business for each reporting segment. Refer to Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” for additional information for each segment.

Gas Distribution Operations

NiSource’s natural gas distribution operations serve more than 3.3 million customers in seven states and operate approximately 58 thousand miles of pipeline. Through its wholly-owned subsidiary, Columbia, NiSource owns five distribution subsidiaries that provide natural gas to approximately 2.2 million residential, commercial and industrial customers in Ohio, Pennsylvania, Virginia, Kentucky, and Maryland. NiSource also distributes natural gas to approximately 795 thousand customers in northern Indiana. Additionally, NiSource’s subsidiary, Columbia Gas of Massachusetts, distributes natural gas to approximately 298 thousand customers in Massachusetts.

Gas Transmission and Storage Operations

NiSource’s Gas Transmission and Storage Operations subsidiaries own and operate approximately 15,000 miles of pipeline and operate one of the nation’s largest underground natural gas storage systems capable of storing approximately 639 Bcf of natural gas. Through its subsidiaries, Columbia Transmission, Columbia Gulf and Crossroads Pipeline, NiSource owns and operates an interstate pipeline network extending from the Gulf of Mexico to New York and the eastern seaboard. Together, these companies serve customers in 16 northeastern, mid-Atlantic, midwestern and southern states and the District of Columbia.

NiSource’s Gas Transmission and Storage Operations continue to develop a range of supply-driven growth initiatives, including mineral leasing and optimization, midstream projects and traditional pipeline expansion opportunities that leverage NiSource’s strategically positioned pipeline and storage assets. A number of Gas Transmission and Storage Operations’ new growth projects are designed to support increasing Marcellus and Utica Shale production, while the segment also has continued to grow and adapt its system to provide critical transportation and storage services to markets across its high-demand service territory. NiSource Midstream Services is an unregulated business that is a provider of midstream services including gathering, treating, conditioning, processing, compression and liquids handling, as well as managing mineral rights positions in the Marcellus and Utica shale areas.

The Gas Transmission and Storage Operations subsidiaries are also involved in two joint ventures, Millennium and Hardy Storage, which effectively expand their facilities and throughput. Millennium Pipeline, which includes 252 miles of 30-inch-diameter pipe across New York’s Southern Tier and lower Hudson Valley, has the capability to transport up to 525,400 Dth per day of natural gas to markets along its route, as well as to the New York City markets through its pipeline interconnections. Millennium is jointly owned by affiliates of NiSource, DTE Energy and National Grid. Hardy Storage, which consists of underground natural gas storage facilities in West Virginia, has a working storage capacity of 12 Bcf and the ability to deliver 176,000 Dth of natural gas per day. Hardy Storage is a joint venture of subsidiaries of Columbia Transmission and Piedmont.

Electric Operations

NiSource generates, transmits and distributes electricity through its subsidiary Northern Indiana to approximately 458 thousand customers in 20 counties in the northern part of Indiana and engages in electric wholesale and transmission transactions. Northern Indiana operates three coal-fired electric generating stations. The three operating

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NISOURCE INC.

facilities have a net capability of 2,574 mw. Northern Indiana also owns and operates Sugar Creek, a CCGT plant with a 535 mw capacity rating, four gas-fired generating units located at Northern Indiana’s coal-fired electric generating stations with a net capability of 203 mw and two hydroelectric generating plants with a net capability of 10 mw. These facilities provide for a total system operating net capability of 3,322 mw. Northern Indiana’s transmission system, with voltages from 69,000 to 345,000 volts, consists of 2,797 circuit miles. Northern Indiana is interconnected with five neighboring electric utilities.

During the year ended December 31, 2011, Northern Indiana generated 83.8% and purchased 16.2% of its electric requirements. Northern Indiana’s Mitchell Station, indefinitely shut down in 2002, is not included in the net capacity of the three coal-fired generation stations.

Northern Indiana participates in the MISO transmission service and wholesale energy market. The 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, the MISO is responsible for managing the energy markets, managing transmission constraints, managing the day-ahead, real-time and FTR markets and managing the ancillary market. Northern Indiana transferred functional control of its electric transmission assets to the MISO and transmission service for Northern Indiana occurs under the MISO Open Access Transmission Tariff.

Corporate and Other Operations

During the first quarter of 2010, NiSource made the decision to wind down its unregulated natural gas marketing activities as a part of the Company’s long-term strategy of focusing on its core regulated business.

Divestiture of Non-Core Assets

In recent years, NiSource sold certain businesses judged to be non-core to NiSource’s strategy. Lake Erie Land, a wholly-owned subsidiary of NiSource, is pursuing the sale of certain real estate assets it owns. NDC Douglas Properties, a subsidiary of NiSource Development Company, is in the process of exiting its low income housing investments.

Business Strategy

NiSource focuses its business strategy on its core, rate-regulated asset-based businesses with most of its operating income generated from the rate-regulated businesses. With one of the nation’s largest natural gas pipelines, one of the largest natural gas distribution networks east of the Rocky Mountains and one of the nation’s largest natural gas storage networks, NiSource operates throughout the energy-intensive corridor that extends from the supply areas in the Gulf Coast through the consumption centers in the Midwest, Mid-Atlantic, New England and Northeast. This corridor includes over 40% of the nation’s population and close to 50% of its natural gas consumption. NiSource continues to position its assets to meet the corridor’s growing energy needs.

Competition and Changes in the Regulatory Environment

The regulatory frameworks applicable to NiSource’s operations, at both the state and federal levels, continue to evolve. These changes have had and will continue to have an impact on NiSource’s operations, structure and profitability. Management continually seeks new ways to be more competitive and profitable in this changing environment, including providing gas customers with increased choices for products and services.

Natural Gas Competition.    Open access to natural gas supplies over interstate pipelines and the deregulation of the commodity price of gas has led to tremendous change in the energy markets. LDC customers and marketers purchase gas directly from producers and marketers as an open, competitive market for gas supplies has emerged. This separation or “unbundling” of the transportation and other services offered by pipelines and LDCs allows customers to purchase the commodity independent of services provided by the pipelines and LDCs. The LDCs continue to purchase gas and recover the associated costs from their customers. NiSource’s Gas Distribution Operations’ subsidiaries are involved in programs that provide customers the opportunity to purchase their natural gas requirements from third parties and use the NiSource Gas Distribution Operations’ subsidiaries for transportation services. The Gas Transmission and Storage Operations compete for transportation customers based on the type of service a customer needs, operating flexibility, available capacity and price under tariff provisions.

Electric Competition.    Northern Indiana currently dispatches all power from its plants into the MISO. Transmission service for Northern Indiana occurs under the MISO Open Access Transmission Tariff.

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Financing Subsidiary

NiSource Finance is a 100% owned, consolidated finance subsidiary of NiSource that engages in financing activities to raise funds for the business operations of NiSource and its subsidiaries. NiSource Finance was incorporated in February 2000 under the laws of the state of Indiana. Prior to 2000, the function of NiSource Finance was performed by Capital Markets. NiSource Finance obligations are fully and unconditionally guaranteed by NiSource.

Other Relevant Business Information

NiSource’s customer base is broadly diversified, with no single customer accounting for a significant portion of revenues.

As of December 31, 2011, NiSource had 7,957 employees of whom 3,295 were subject to collective bargaining agreements.

For a listing of certain subsidiaries of NiSource refer to Exhibit 21.

NiSource files various reports with the SEC. The reports include the annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, proxy statements, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934. NiSource makes all SEC filings available without charge to the public on its web site at http://www.nisource.com.

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ITEM 1A. RISK FACTORS

NISOURCE INC.

There are many factors that could have a material adverse effect on NiSource’s operating results, financial condition and cash flows. New risks may emerge at any time, and NiSource cannot predict those risks or estimate the extent to which they may affect financial performance. Each of the risks described below could adversely impact the value of NiSource’s securities.

NiSource has substantial indebtedness which could adversely affect its financial condition.

NiSource had total consolidated indebtedness of $7,953.8 million outstanding as of December 31, 2011. The substantial indebtedness could have important consequences to investors. For example, it could:

Some of NiSource’s debt obligations contain financial covenants related to debt-to-capital ratios and cross-default provisions. NiSource’s failure to comply with any of these covenants could result in an event of default, which, if not cured or waived, could result in the acceleration of outstanding debt obligations. Additionally, a drop in NiSource’s credit rating could adversely impact the cost for NiSource to issue new debt securities.

A drop in NiSource’s credit rating could adversely impact NiSource’s liquidity.

On December 13, 2011, Fitch affirmed the senior unsecured ratings for NiSource at BBB-, and the existing ratings of all other subsidiaries. Fitch’s outlook for NiSource and all of its subsidiaries is stable. On November 18, 2011, Moody’s Investors Service affirmed the senior unsecured ratings for NiSource at Baa3, and the existing ratings of all other subsidiaries. Moody’s outlook for NiSource and all of its subsidiaries is stable. On February 24, 2011, Standard & Poor’s affirmed the senior unsecured ratings for NiSource and its subsidiaries at BBB-. Standard & Poor’s outlook for NiSource and all of its subsidiaries is stable. Although all ratings continue to be investment grade, a downgrade by Standard & Poor’s, Moody’s or Fitch would result in a rating that is below investment grade.

Certain NiSource affiliates have agreements that contain “ratings triggers” that require increased collateral if the credit ratings of NiSource or certain of its subsidiaries are rated below BBB- by Standard & Poor’s or Baa3 by Moody’s. These agreements are primarily for insurance purposes and for the physical purchase or sale of power. The collateral requirement from a downgrade below the ratings trigger levels would amount to approximately $21.0 million. In addition to agreements with ratings triggers, there are other agreements that contain “adequate assurance” or “material adverse change” provisions that could necessitate additional credit support such as letters of credit and cash collateral to transact business. Under Northern Indiana’s trade receivables sales program, an event of termination occurs if Northern Indiana’s debt rating is withdrawn by either Standard & Poor’s or Moody’s or falls below BB or Ba2 at either Standard & Poor’s or Moody’s, respectively. Likewise, under Columbia of Ohio’s and Columbia of Pennsylvania’s trade receivables sales programs, an event of termination occurs if NiSource’s debt rating is withdrawn by either Standard & Poor’s or Moody’s, or falls below BB- or Ba3 at either Standard & Poor’s or Moody’s, respectively.

Additionally, as a result of NiSource’s participation in certain derivative activities, a credit downgrade could cause NiSource to be required to post substantial collateral in support of past and current transactions. These collateral requirements, combined with other potential negative effects on NiSource’s liquidity in the event of a credit downgrade below an investment grade rating, could have a material adverse effect on earnings potential and cash flows. Lastly, a credit downgrade could adversely affect the availability and cost of capital needed to fund the growth investments which are a central element of the Company’s long-term business strategy.

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NISOURCE INC.

NiSource may not be able to execute its growth strategy as planned.

Because of changes in the business or regulatory environment, NiSource may not be able to execute its four-part business plan as intended. NiSource’s commercial and regulatory initiatives may not achieve planned results; levels of commercial growth and expansion of the gas transmission and storage business may be less than its plan has anticipated; and the actual results of NiSource’s financial management of the balance sheet, and process and expense management could deviate materially from planned outcomes.

Adverse economic and market conditions or increases in interest rates could reduce net revenue growth, increase costs, decrease future net income and cash flows and impact capital resources and liquidity needs.

While the national economy is experiencing some recovery from the recent downturn, NiSource cannot predict how robust the recovery will be or whether or not it will be sustained.

Continued sluggishness in the economy impacting NiSource’s operating jurisdictions could adversely impact NiSource’s ability to grow its customer base and collect revenues from customers, which could reduce net revenue growth and increase operating costs. An increase in the interest rates NiSource pays would adversely affect future net income and cash flows. In addition, NiSource depends on debt to finance its operations, including both working capital and capital expenditures, and would be adversely affected by increases in interest rates. If the current economic recovery remains slow or credit markets again tighten, NiSource’s ability to raise additional capital or refinance debt at a reasonable cost could be negatively impacted. Refer to Note 16, “Long-Term Debt,” in the Notes to Consolidated Financial Statements for information related to outstanding long-term debt and maturities of that debt.

Capital market performance and other factors may decrease the value of benefit plan assets, which then could require significant additional funding and impact earnings.

The performance of the capital markets affects the value of the assets that are held in trust to satisfy future obligations under defined benefit pension and other postretirement benefit plans. NiSource has significant obligations in these areas and holds significant assets in these trusts. These assets are subject to market fluctuations and may yield uncertain returns, which fall below NiSource’s projected rates of return. A decline in the market value of assets may increase the funding requirements of the obligations under the defined benefit pension and other postretirement benefit plans. Additionally, changes in interest rates affect the liabilities under these benefit plans; as interest rates decrease, the liabilities increase, which could potentially increase funding requirements. Further, the funding requirements of the obligations related to these benefits plans may increase due to changes in governmental regulations and participant demographics, including increased numbers of retirements or changes in life expectancy assumptions. Ultimately, significant funding requirements and increased pension expense could negatively impact NiSource’s results of operations and financial position.

The majority of NiSource’s net revenues is subject to economic regulation and is exposed to the impact of regulatory rate reviews and proceedings.

Most of NiSource’s net revenues are subject to economic regulation at either the federal or state level. As such, the net revenues generated by those regulated companies are subject to regulatory review by the applicable federal or state authority. These rate reviews determine the energy rates charged to customers and directly impact revenues. NiSource’s financial results are dependent on frequent regulatory proceedings in order to ensure timely recovery of costs. Additionally, the costs of complying with future changes in environmental laws and regulations are expected to be significant, and their recovery through rates will be contingent on regulatory approval.

As a result of efforts to introduce market-based competition in certain of the markets where the regulated businesses conduct operations, NiSource may compete with independent marketers for customers. This competition exposes NiSource to the risk that certain stranded costs may not be recoverable and may affect results of NiSource’s growth strategy and cash flows.

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NISOURCE INC.

NiSource’s costs of compliance with environmental laws are significant. The costs of compliance with future environmental laws and the recognition of environmental liabilities could impact cash flow and profitability.

NiSource’s subsidiaries are subject to extensive federal, state and local environmental requirements that, among other things, regulate air emissions, water usage and discharges, remediation and the management of chemicals, hazardous waste, solid waste, and coal combustion residuals. Compliance with these legal obligations requires NiSource to make expenditures for installation of pollution control equipment, remediation, environmental monitoring, emissions fees and permits at many of NiSource’s facilities. These expenditures are significant, and NiSource expects that they will continue to be significant in the future. Furthermore, if NiSource’s subsidiaries fail to comply with environmental laws and regulations or cause harm to the environment or persons, even if caused by factors beyond NiSource’s control, that failure or harm may result in the assessment of civil or criminal penalties and damages against NiSource and its subsidiaries.

Existing environmental laws and regulations may be revised and new laws and regulations seeking to protect the environment may be adopted or become applicable to NiSource’s subsidiaries. Revised or additional laws and regulations could result in significant additional expense and operating restrictions on NiSource’s facilities or increased compliance costs, which may not be fully recoverable from customers and would, therefore, reduce net income. Moreover, such costs could materially affect the continued economic viability of one or more of NiSource’s facilities.

Because NiSource’s operations deal with natural gas and coal fossil fuels, emissions of GHGs are an expected aspect of the business. While NiSource attempts to reduce GHG emissions through efficiency programs, leak detection, and other programs, GHG emissions cannot be entirely eliminated. The current administration has made it clear that it is focused on reducing GHG emissions, through legislation and/or regulation. Imposing statutory or regulatory restrictions and/or costs on GHG emissions could increase NiSource’s cost of producing energy, which could impact customer demand or NiSource’s profitability. Compliance costs associated with these requirements could also affect NiSource’s cash flow. The cost impact of any new or amended GHG legislation or regulations would depend upon the specific requirements enacted and cannot be determined at this time.

Even in instances where legal and regulatory requirements are already known, the original estimates for cleanup and environmental capital projects can differ materially from the amount ultimately expended. The actual future expenditures depend on many factors, including the nature and extent of contamination, the method of cleanup, the cost of raw materials, contractor costs, and the availability of cost recovery from customers. Changes in costs could affect NiSource’s financial position and cash flows.

A significant portion of the gas and electricity NiSource sells is used by residential and commercial customers for heating and air conditioning. Accordingly, the operating results fluctuate depending on the weather and, to a certain extent, usage of gas or electricity.

Energy sales are sensitive to variations in weather. Forecasts of energy sales are based on normal weather, which represents a long-term historical average. Significant variations from normal weather could have, and have had, a material impact on energy sales. Additionally, residential usage, and to some degree commercial usage, have shown to be sensitive to fluctuations in commodity costs for gas and electricity, whereby usage declines with increased costs, thus affecting NiSource’s financial results. Lastly, residential and commercial customers’ usage has shown to be sensitive to economic conditions and the impact of macro-economic drivers such as unemployment, consumption and consumer confidence, which could also affect NiSource’s financial results.

NiSource’s business operations are subject to economic conditions in certain industries.

Business operations throughout NiSource’s service territories have been and may continue to be adversely affected by economic events at the national and local level where it operates. In particular, sales to large industrial customers may be impacted by economic downturns. The U.S. manufacturing industry continues to adjust to changing market conditions including international competition, increasing costs, and fluctuating demand for its products.

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Fluctuations in the price of energy commodities or their related transportation costs may have a negative impact on NiSource’s financial results.

NiSource’s electric generating fleet is dependent on coal and natural gas for fuel, and its gas distribution operations purchase and resell much of the natural gas they deliver. These energy commodities are vulnerable to price fluctuations and fluctuations in associated transportation costs. Hedging activities have been deployed in order to offset fluctuations in commodity supply prices and NiSource relies on regulatory recovery mechanisms in the various jurisdictions in order to fully recover the costs incurred in operations. However, while NiSource has historically been successful in recovery of costs related to such commodity prices, there can be no assurance that such costs will be fully recovered through rates in a timely manner. Additionally, increased gas and electricity costs could result in reduced demand from customers as a result of increased conservation activities.

NiSource is exposed to risk that customers will not remit payment for delivered energy or services, and that suppliers or counterparties will not perform under various financial or operating agreements.

NiSource’s extension of credit is governed by a Corporate Credit Risk Policy, involves considerable judgment and is based on an evaluation of a customer or counterparty’s financial condition, credit history and other factors. Credit risk exposure is monitored by obtaining credit reports and updated financial information for customers and suppliers, and by evaluating the financial status of its banking partners and other counterparties through the use of market-based metrics such as credit default swap pricing levels, and also through traditional credit ratings provided by the major credit rating agencies. Continued adverse economic conditions could increase credit risk and could result in a material adverse effect on NiSource.

NiSource has significant goodwill and definite-lived intangible assets. An impairment of goodwill or definite-lived intangible assets could result in a significant charge to earnings.

In accordance with GAAP, NiSource tests goodwill for impairment at least annually and reviews its definite-lived intangible assets for impairment when events or changes in circumstances indicate the carrying value may not be recoverable. Goodwill would also be tested for impairment when factors, examples of which include reduced cash flow estimates, a sustained decline in stock price or market capitalization below book value, indicate that the carrying value may not be recoverable. NiSource would be required to record a charge in the financial statements during the period in which any impairment of the goodwill or definite-lived intangible assets is determined, negatively impacting the results of operations. A significant charge could impact the capitalization ratio covenant under certain financing agreements. A covenant in the four-year revolving credit facility requires NiSource to maintain a debt to capitalization ratio that does not exceed 70%. A similar covenant in a 2005 private placement note purchase agreement requires NiSource to maintain a debt to capitalization ratio that does not exceed 75%. As of December 31, 2011, the ratio was 61.4%.

Changes in taxation and the ability to quantify such changes could adversely affect NiSource’s financial results.

NiSource is subject to taxation by the various taxing authorities at the federal, state and local levels where it does business. Legislation or regulation which could affect NiSource’s tax burden could be enacted by any of these governmental authorities. NiSource cannot predict the timing or extent of such tax-related developments which could have a negative impact on the financial results. Additionally, NiSource uses its best judgment in attempting to quantify and reserve for these tax obligations. However, a challenge by a taxing authority, NiSource’s ability to utilize tax benefits such as carryforwards or tax credits, or a deviation from other tax-related assumptions may cause actual financial results to deviate from previous estimates.

Changes in accounting principles may adversely affect NiSource’s financial results.

Future changes in accounting rules, such as IFRS, and associated changes in regulatory accounting may negatively impact the way NiSource records revenues, expenses, assets and liabilities. These changes in accounting standards may adversely affect its financial results.

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NISOURCE INC.

Transporting and storing natural gas involves numerous risks that may result in accidents and other operating risks and costs.

NiSource’s gas distribution and gas transmission and storage activities involve a variety of inherent hazards and operating risks, such as leaks, accidents, including third party damages, and mechanical problems, which could cause substantial financial losses. In addition, these risks could result in serious injury to employees and non-employees, loss of human life, significant damage to property, environmental pollution and impairment of its operations, which in turn could lead to substantial losses to NiSource. In accordance with customary industry practice, NiSource maintains insurance against some, but not all, of these risks and losses. The location of pipelines and storage facilities near populated areas, including residential areas, commercial business centers and industrial sites, could increase the level of damages resulting from these risks. The occurrence of any of these events not fully covered by insurance could adversely affect NiSource’s financial position and results of operations.

Aging infrastructure may lead to increased costs and disruptions in operations that could negatively impact NiSource’s financial results.

NiSource has risks associated with aging infrastructure assets. The age of these assets may result in replacement, a higher level of maintenance costs and may be susceptible to unscheduled outages despite diligent efforts by NiSource to properly maintain these assets through inspection, scheduled maintenance and capital investment. The failure to operate these assets as desired could result in NiSource’s inability to meet firm service obligations, adversely impact revenues, and could result in increased capital expenditures and expenses, which may not be fully recoverable from customers.

Climate change, natural disasters, acts of terrorism, cyber-attacks or other catastrophic events may disrupt operations and reduce the ability to service customers.

A disruption or failure of natural gas transmission, storage or distribution systems or within electric generation, transmission or distribution systems in the event of a major hurricane, tornado, terrorist attack or other catastrophic event could cause delays in completing sales, providing services, or performing other critical functions. NiSource has experienced disruptions in the past from hurricanes and tornadoes and other events of this nature. The cost, availability and sufficiency of insurance for these risks could adversely affect NiSource’s results of operations, financial position and cash flows.

There is also a concern that climate change may exacerbate the risks to physical infrastructure associated with heat and extreme weather conditions. Climate change and the costs that may be associated with its impacts have the potential to affect NiSource’s business in many ways, including increasing the cost NiSource incurs in providing its products and services, impacting the demand for and consumption of its products and services (due to change in both costs and weather patterns), and affecting the economic health of the regions in which NiSource operates.

Additionally, a security breach of NiSource’s information systems could (i) impact the reliability of NiSource’s generation, transmission storage and distribution systems and potentially negatively impact NiSource’s compliance with certain mandatory reliability standards (ii) subject NiSource to harm associated with theft or inappropriate release of certain types of information such as system operating information or information, personal or otherwise, relating to NiSource’s customers or employees, or (iii) impact NiSource’s ability to manage NiSource’s businesses.

Growing NiSource’s business by constructing new pipelines and other facilities subjects NiSource to construction risks and natural gas supply risks.

NiSource Gas Transmission & Storage Operations continues to complete and advance customer-driven growth projects across its system, primarily surrounding the Marcellus and Utica Shale production area in the states of Pennsylvania, Ohio and West Virginia. These growth projects may include constructing or purchasing pipelines and treatment and processing facilities, which subjects NiSource to construction risks and risks that gas supplies will not be available. If NiSource undertakes these projects, it may not be able to complete them on schedule or at the anticipated costs. NiSource may construct or purchase these projects to capture anticipated future growth in production in the region, which may not materialize, and the construction may occur over an extended period of time, and NiSource will not receive material increases in revenue and cash flows until after the completion of the project. NiSource competes for these projects with companies of varying size and financial capabilities, including some that may have advantages competing for natural gas and liquid gas supplies, as well as acquisitions and other business opportunities.

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Sustained extreme weather conditions may negatively impact NiSource’s operations.

NiSource conducts its operations across a wide geographic area subject to varied and potentially extreme weather conditions, which may from time to time persist for sustained periods of time. Despite preventative maintenance efforts, persistent weather related stress on NiSource’s infrastructure may reveal weaknesses in its systems not previously known to the Company or otherwise present various operational challenges across all business segments. Although NiSource makes every effort to plan for weather related contingencies, adverse weather may affect its ability to conduct operations in a manner that satisfies customer expectations or contractual obligations. The Company endeavors to minimize such service disruptions, but may not be able to avoid them altogether.

Growing competition in the gas transportation industry could result in the failure by customers to renew existing contracts.

As a consequence of the increase in competition in the industry and the shift in natural gas production areas, end users and LDCs may be reluctant to enter into long-term service contracts. The renewal or replacement of existing contracts with NiSource’s customers at rates sufficient to maintain current or projected revenues and cash flows depends on a number of factors beyond its control, including competition from other pipelines, gatherers, the proximity of supplies to the markets, and the price of, and demand for, natural gas. The inability of NiSource to renew, or replace its current contracts as they expire and respond appropriately to changing market conditions could materially impact its financial results.

NiSource is a holding company and is dependent on cash generated by subsidiaries to meet its debt obligations and pay dividends on its common stock.

NiSource is a holding company and conducts its operations primarily through its subsidiaries. Substantially all of NiSource’s consolidated assets are held by its subsidiaries. Accordingly, NiSource’s ability to meet its debt obligations or pay dividends on its common stock is largely dependent upon cash generated by these subsidiaries. In the event a major subsidiary is not be able to pay dividends or transfer cash flows to NiSource, its ability to service its debt obligations or pay dividends could be negatively affected.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

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ITEM 2. PROPERTIES

NISOURCE INC.

Discussed below are the principal properties held by NiSource and its subsidiaries as of December 31, 2011.

Gas Distribution Operations. NiSource’s Gas Distribution Operations subsidiaries own and operate a total of 57,717 miles of pipelines and certain related facilities. This includes: (i) for the six distribution companies of its Columbia system, 40,417 miles of pipelines, 1,350 reservoir acres of underground storage, eight storage wells, liquid propane facilities with a capacity of 3.3 million gallons, an LNG facility with a total capacity of 22.3 million gallons and one compressor station with 800 hp of installed capacity, (ii) for its Northern Indiana system, 17,300 miles of pipelines, 27,129 reservoir acres of underground storage, 55 storage wells, one compressor station with a total of 4,000 hp of installed capacity and two LNG facilities with a storage capacity of 53.6 million gallons. The physical properties of the NiSource gas utilities are located throughout Ohio, Indiana, Pennsylvania, Virginia, Kentucky, Maryland, and Massachusetts.

Gas Transmission and Storage Operations. NiSource Gas Transmission and Storage subsidiaries own and operate 15,060 miles of natural gas transmission pipeline. Columbia Transmission owns and leases approximately 775 thousand acres of underground storage, 3,491 storage wells, 11,453 miles of pipeline and 91 compressor stations with 624,179 hp of installed capacity. Columbia Transmission’s operations are located in Delaware, Kentucky, Maryland, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Virginia, and West Virginia. Columbia Gulf has 3,405 miles of transmission pipeline and 11 compressor stations with 470,238 hp of installed capacity. Columbia Gulf’s operations are located in Kentucky, Louisiana, Mississippi, Tennessee, Texas and Wyoming. Crossroads Pipeline has 202 miles of transmission pipeline and one compressor station with 3,000 hp of installed capacity. Crossroads Pipeline’s operations are located in Indiana and Ohio. NiSource Gas Transmission and Storage Operations’ offices are headquartered in Houston, Texas.

Electric Operations. NiSource generates, transmits and distributes electricity through its subsidiary Northern Indiana to approximately 458 thousand customers in 20 counties in the northern part of Indiana and engages in wholesale and transmission transactions. Northern Indiana operates three coal-fired electric generating stations. The three operating facilities have a net capability of 2,574 mw. Northern Indiana also owns and operates Sugar Creek, a CCGT plant with a 535 mw capacity rating, four gas-fired generating units located at Northern Indiana’s coal-fired electric generating stations with a net capability of 203 mw and two hydroelectric generating plants with a net capability of 10 mw. These facilities provide for a total system operating net capability of 3,322 mw. Northern Indiana’s transmission system, with voltages from 69,000 to 345,000 volts, consists of 2,797 circuit miles. Northern Indiana is interconnected with five neighboring electric utilities.

During the year ended December 31, 2011, Northern Indiana generated 83.8% and purchased 16.2 % of its electric requirements. Northern Indiana’s Mitchell Station, indefinitely shut down in 2002, is not included in the net capacity of the three coal-fired generation stations.

Corporate and Other Operations. NiSource owns the Southlake Complex, its 325,000 square foot headquarters building located in Merrillville, Indiana, and other residential and development property.

Character of Ownership. The principal offices and properties of NiSource and its subsidiaries are owned free from encumbrances, subject to minor exceptions, none of which are of such a nature as to impair substantially the usefulness of such properties. Many of the offices in various communities served are occupied by subsidiaries of NiSource under leases. All properties are subject to routine liens for taxes, assessments and undetermined charges (if any) incidental to construction. It is NiSource’s practice regularly to pay such amounts, as and when due, unless contested in good faith. In general, the electric lines, gas pipelines and related facilities are located on land not owned by NiSource and its subsidiaries, but are covered by necessary consents of various governmental authorities or by appropriate rights obtained from owners of private property. NiSource does not, however, generally have specific easements from the owners of the property adjacent to public highways over, upon or under which its electric lines and gas distribution pipelines are located. At the time each of the principal properties was purchased a title search was made. In general, no examination of titles as to rights-of-way for electric lines, gas pipelines or related facilities was made, other than examination, in certain cases, to verify the grantors’ ownership and the lien status thereof.

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ITEM 3. LEGAL PROCEEDINGS

NISOURCE INC.

Majorsville Operations Center – PADEP Notice of Violation

In 1995, Columbia Transmission entered into an AOC with the EPA that requires Columbia Transmission to characterize and remediate environmental contamination at thousands of locations along Columbia Transmission’s pipeline system. One of the facilities subject to the AOC is the Majorsville Operations Center, which was remediated under an EPA approved Remedial Action Work Plan in summer 2008. Pursuant to the Remedial Action Work Plan, Columbia Transmission completed a project that stabilized residual oil contained in soils at the site and in sediments in an adjacent stream.

On April 23, 2009, however, the PADEP issued Columbia Transmission an NOV, alleging that the remediation was not effective. The NOV asserts violations of the Pennsylvania Clean Streams Law and the Pennsylvania Solid Waste Management Act and contains a settlement demand in the amount of $1 million. Columbia Transmission is unable to estimate the likelihood or cost of potential penalties or additional remediation at this time.

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ITEM 4. Mine Safety Disclosures

NISOURCE INC.

Not applicable.

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SUPPLEMENTAL ITEM. EXECUTIVE OFFICERS OF THE REGISTRANT

NISOURCE INC.

The following is a list of the Executive Officers of the Registrant, including their names, ages and offices held, as of February 1, 2012.

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PART II

ITEM 5. MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

NISOURCE INC.

NiSource’s common stock is listed and traded on the New York Stock Exchange under the symbol “NI.” The table below indicates the high and low sales prices of NiSource’s common stock, on the composite tape, during the periods indicated.

As of December 31, 2011, NiSource had 30,663 common stockholders of record and 281,853,571 shares outstanding.

Holders of shares of NiSource’s common stock are entitled to receive dividends when, as and if declared by NiSource’s Board out of funds legally available. The policy of the Board has been to declare cash dividends on a quarterly basis payable on or about the 20th day of February, May, August and November. NiSource paid quarterly common dividends totaling $0.92 per share for the years ended December 31, 2011, 2010, and 2009. At its January 27, 2012 meeting, the Board declared a quarterly common dividend of $0.23 per share, payable on February 20, 2012 to holders of record on February 6, 2012.

Although the Board currently intends to continue the payment of regular quarterly cash dividends on common shares, the timing and amount of future dividends will depend on the earnings of NiSource’s subsidiaries, their financial condition, cash requirements, regulatory restrictions, any restrictions in financing agreements and other factors deemed relevant by the Board.

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ITEM 6. SELECTED FINANCIAL DATA

NISOURCE INC.

The selected data presented below as of and for the years ended December 31, 2011, 2010, 2009, 2008 and 2007 are derived from the Consolidated Financial Statements of NiSource. The data should be read in connection with the Consolidated Financial Statements including the related notes included in Item 8 of this Form 10-K. Certain correcting adjustments have been made to the prior period amounts as discussed in Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations and as discussed in Item 8, Note 1 to the Consolidated Financial Statements.

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ITEM 6. SELECTED FINANCIAL DATA

NISOURCE INC.

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ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

NISOURCE INC.

Note regarding forward-looking statements

The Management’s Discussion and Analysis, including statements regarding market risk sensitive instruments, contains “forward-looking statements,” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Investors and prospective investors should understand that many factors govern whether any forward-looking statement contained herein will be or can be realized. Any one of those factors could cause actual results to differ materially from those projected. These forward-looking statements include, but are not limited to, statements concerning NiSource’s plans, objectives, expected performance, expenditures and recovery of expenditures through rates, stated on either a consolidated or segment basis, and any and all underlying assumptions and other statements that are other than statements of historical fact. From time to time, NiSource may publish or otherwise make available forward-looking statements of this nature. All such subsequent forward-looking statements, whether written or oral and whether made by or on behalf of NiSource, are also expressly qualified by these cautionary statements. All forward-looking statements are based on assumptions that management believes to be reasonable; however, there can be no assurance that actual results will not differ materially.

Realization of NiSource’s objectives and expected performance is subject to a wide range of risks and can be adversely affected by, among other things, weather, fluctuations in supply and demand for energy commodities, growth opportunities for NiSource’s businesses, increased competition in deregulated energy markets, the success of regulatory and commercial initiatives, dealings with third parties over whom NiSource has no control, actual operating experience of NiSource’s assets, the regulatory process, regulatory and legislative changes, the impact of potential new environmental laws or regulations, the results of material litigation, changes in pension funding requirements, changes in general economic, capital and commodity market conditions, and counter-party credit risk, and the matters set forth in Item 1A, “Risk Factors” of this report, many of which risks are beyond the control of NiSource. In addition, the relative contributions to profitability by each segment, and the assumptions underlying the forward-looking statements relating thereto, may change over time.

CONSOLIDATED REVIEW

Executive Summary

NiSource is an energy holding company whose subsidiaries are engaged in the transmission, storage and distribution of natural gas in the high-demand energy corridor stretching from the Gulf Coast through the Midwest to New England and the generation, transmission and distribution of electricity in Indiana. NiSource generates most of its operating income through these rate-regulated businesses. A significant portion of NiSource’s operations is subject to seasonal fluctuations in sales. During the heating season, which is primarily from November through March, net revenues from gas sales are more significant, and during the cooling season, which is primarily from June through September, net revenues from electric sales and transportation services are more significant than in other months.

For the twelve months ended December 31, 2011, NiSource reported income from continuing operations of $303.8 million, or $1.08 per basic share, compared to $285.2 million, or $1.03 per basic share for the same period in 2010.

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ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

NISOURCE INC.

Increases in income from continuing operations were due primarily to the following items:

Increases in income from continuing operations were partially offset due to the following items:

These factors and other impacts to the financial results are discussed in more detail within the following discussions of “Results of Operations” and “Results and Discussion of Segment Operations.”

Four-Point Platform for Growth

NiSource’s four key initiatives to build a platform for long-term, sustainable growth continue to comprise commercial and regulatory initiatives; commercial growth and expansion of the gas transmission and storage business; financial management of the balance sheet; and process and expense management.

Commercial and Regulatory Initiatives

Rate Development and Other Regulatory Matters. NiSource is moving forward with regulatory initiatives across several gas distribution company markets, at Northern Indiana, and at Columbia Gulf. Whether through full rate case filings or other approaches, NiSource’s goal is to develop strategies that benefit all stakeholders as it addresses changing customer conservation patterns, develops more contemporary pricing structures, and embarks on long-term investment programs to enhance its infrastructure.

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ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

NISOURCE INC.

On December 28, 2011, the IURC issued an Order approving Northern Indiana’s proposed gas energy efficiency programs and budgets, including a conservation program and recovery of all start-up and deferred costs. A three year budget of $42.4 million for these programs was approved. In its Order the IURC recognized that Northern Indiana was one of two utilities in the state in a position to integrate its gas and electric energy efficiency programs throughout its service territory footprint. Northern Indiana is presently working through implementation plans.

On June 1, 2011, Columbia of Virginia filed an application for approval of an infrastructure tracking mechanism pursuant to the Steps to Advance Virginia’s Energy (“SAVE”) Plan Act. Columbia of Virginia’s SAVE Plan provides for recovery of costs associated with the accelerated replacement of certain facilities designed to improve system safety or reliability through a rate rider. The proposed replacement program would result in investments of $20 million per year from 2012 through 2016, as well as covering $2.9 million in investment occurring in 2011. The Staff of the VSCC filed responsive testimony on August 22, 2011 and a public hearing was held on September 7, 2011. The Hearing Examiner issued a Report on October 6, 2011 recommending approval of the SAVE Plan. The VSCC issued an Order on November 28, 2011 approving the SAVE Plan and the associated rider effective December 30, 2011.

On January 14, 2011, Columbia of Pennsylvania filed a base rate case with the Pennsylvania PUC, seeking a revenue increase of approximately $37.8 million annually. The parties to the case jointly filed a petition for approval of a partial settlement on July 1, 2011. The partial settlement resolved all issues except residential rate design and a challenge to the structure of one of Columbia of Pennsylvania’s customer programs. The settlement provides for an annual revenue increase of $17 million. The Pennsylvania PUC issued an order on October 14, 2011 approving the annual revenue increase of $17 million. New rates went into effect on October 18, 2011. The Pennsylvania PUC’s ruling increased the minimum residential customer charge from $12.25 to $18.73, which includes an allowance for 20 Ccf of distribution charges. However, the customer pays for gas commodity on all usage.

On November 30, 2010, Columbia of Ohio filed a notice of intent to file an application to adjust rates associated with Rider IRP and Rider DSM. On February 28, 2011, Columbia of Ohio filed its application to adjust rates associated with the IRP and DSM Riders. The DSM Rider tracks and recovers costs associated with Columbia of Ohio’s energy efficiency and conservation programs. The application sought to increase the annual revenue from the riders by approximately $24 million. On April 7, 2011, the parties filed a stipulation that settled this case, which was approved as filed by the PUCO on April 27, 2011. The Order allowed Columbia of Ohio to increase its annual revenues by approximately $24 million effective May 1, 2011.

On September 9, 2011, Columbia of Ohio filed an application with PUCO to continue and expand its DSM program. In its application, Columbia of Ohio proposed to spend $20 million annually (adjusted for inflation) on weatherization programs for residential and commercial customers for calendar years 2012 through 2016. Columbia of Ohio will continue to recover program expenses through Rider DSM and has proposed a shared savings incentive not to exceed $3.9 million over the five-year program. By Order dated December 14, 2011, the PUCO approved a stipulation filed in the case.

On October 28, 2010, Columbia Gulf filed a rate case with the FERC, proposing a rate increase and tariff changes. Among other things, the filing proposed a revenue increase of approximately $50 million to cover increases in the cost of services, which included adjustments for operation and maintenance expenses, capital investments, adjustments to depreciation rates and expense, rate of return, and increased federal, state and local taxes. On November 30, 2010, the FERC issued an Order allowing new rates to become effective by May 2011, subject to refund. Columbia Gulf placed new rates into effect, subject to refund, on May 1, 2011. Columbia Gulf and the active parties to the case negotiated a settlement, which was filed with the FERC on September 9, 2011. On September 30, 2011, the Chief Judge severed the issues relating to a contesting party for separate hearing and decision. On October 4, 2011, the Presiding Administrative Law Judge certified the settlement agreement as uncontested to the FERC with severance of the contesting party from the settlement. On November 1, 2011, Columbia Gulf began billing interim rates to customers. On December 1, 2011, the FERC issued an Order approving the settlement without change. The key elements of the settlement, which was a “black box agreement”, include: (1) increased base rate to $0.1520 per Dth and (2) establishing a postage stamp rate design. No protests to the Order were filed and therefore, pursuant to the Settlement, the order became final on January 1, 2012 which made the settlement effective on February 1, 2012. On February 2, 2012, the Presiding Administrative Law Judge issued an initial decision granting a joint motion terminating the remaining litigation with the contesting party and allowing it to become a settling party. Refunds of approximately $16 million, accrued as of December 31, 2011, are to be issued before the end of March 2012.

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NISOURCE INC.

On July 18, 2011, Northern Indiana filed with the IURC a settlement in its 2010 Electric Rate Case with the OUCC, Northern Indiana Industrial Group, NLMK Indiana and Indiana Municipal Utilities Group. The settlement agreement limited the proposed base rate impact to the residential customer class to a 4.5% increase. The parties have also agreed to a rate of return of 6.98% based upon a 10.2% return on equity. The settlement also resolves all pending issues related to compliance with the August 25, 2010 Order in the 2008 Electric Rate Case. On December 21, 2011, the IURC issued an Order approving the Settlement Agreement as filed, and new electric base rates became effective on December 27, 2011. On January 20, 2012, the City of Hammond filed an appeal of the IURC’s December 21, 2011 Order. That appeal is pending.

On March 22, 2011, Northern Indiana filed a petition with the IURC for a certificate of public convenience and necessity and associated relief for the construction of additional environmental projects required to comply with the NOV consent decree lodged in the United States District Court for the Northern District of Indiana on January 13, 2011. Refer to Note 20-D, “Environmental Matters,” for additional information. This petition has since been trifurcated into three separate phases. In terms of Phase I, the evidentiary hearing was held at the IURC on August 31, 2011 addressing the relief regarding (i) the construction of a FGD unit at R.M. Schahfer Generating Station Unit 15 and (ii) a cost estimate increase for the projects approved by the December 29, 2010 Order, which included estimates for a FGD unit at R.M. Schahfer Generating Station Unit 14 and associated common facilities for Units 14 and 15. On December 28, 2011, the IURC issued an order for the Phase I projects estimated to cost $500 million and granting the requested ratemaking and accounting relief associated with these Phase I projects. On November 9, 2011, Northern Indiana filed with the IURC a stipulation and settlement agreement with the OUCC and the Industrial Group resolving all issues regarding the Phase II projects, which includes all remaining projects with the exception of those projects related to Michigan City Generating Station Unit 12. The motion also requested the establishment of and a procedural schedule for a new Phase III for the Unit 12 projects. The evidentiary hearing was held for the Phase II projects at the IURC on December 14, 2011. On February 15, 2012, the IURC approved the stipulation and settlement agreement. The establishment of a Phase III in this proceeding occurred in response to the fact that on October 20, 2011 and October 21, 2011, the OUCC and the Industrial Group, respectively, filed testimony in opposition of the proposed construction of a FGD unit on Michigan City Generating Station Unit 12. On February 14, 2012, the IURC set a procedural schedule for the Phase III projects.

As part of a multi-state effort to strengthen the electric transmission system serving the Midwest, Northern Indiana anticipates making an investment in a new, 100-mile, 345-kilovolt transmission project in northern Indiana. The project, a major new transmission system improvement reviewed and authorized by the MISO, is scheduled to be in service during the latter part of the decade. Northern Indiana has also been identified by the MISO as one of two Transmission Owners to invest in another project. On February 8, 2012, Pioneer Transmission, LLC filed a complaint with the FERC, seeking to obtain 100% of the investment rights in this second project.

Refer to Note 8, “Regulatory Matters,” in the Notes to Consolidated Financial Statements for a complete discussion of regulatory matters.

Commercial Growth and Expansion of the Gas Transmission and Storage Business

During 2011, Gas Transmission and Storage Operations placed into service strategic growth projects, primarily serving the Marcellus Shale production area. Below is a discussion of these projects as well as projects that are currently on-going.

Majorsville, PA Project. The Gas Transmission and Storage Operations segment executed three separate projects totaling approximately $80 million in the Majorsville, PA vicinity to aggregate Marcellus Shale gas production for downstream transmission. Fully contracted, the pipeline and compression assets allow Gas Transmission and Storage Operations segment to gather and deliver more than 325,000 Dth per day of Marcellus production gas to the Majorsville MarkWest Liberty processing plants developed by MarkWest Liberty Midstream & Resources L.L.C.

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NISOURCE INC.

In 2010, Columbia Transmission received approval from the FERC to refunctionalize certain transmission assets to gathering and transferred these pipeline facilities to a newly formed affiliate, NiSource Midstream Services, LLC. These facilities are included in providing non-FERC jurisdiction gathering services to producers in the Majorsville, PA vicinity. Two of the three projects were completed and placed into service on August 1, 2010, creating an integrated gathering and processing system serving Marcellus production in southwestern Pennsylvania and northern West Virginia. Precedent agreements were executed by anchor shippers in the fourth quarter of 2009, which were superseded by the execution of long-term service agreements in August and September 2010. In the fourth quarter, construction began on the third project on a pipeline to deliver residue gas from the Majorsville MarkWest Liberty processing plant to the Texas Eastern Wind Ridge compressor station in southwestern Pennsylvania to provide significant additional capacity to eastern markets. This project was placed into service in April 2011.

Clendenin Project. Construction began on this approximately $18 million capital project in 2010 to modify existing facilities in the Clendenin, West Virginia area to move Marcellus production to liquid market centers. The Clendenin project provides the Gas Transmission and Storage Operations segment the ability to meet incremental transportation demand of up to 150,000 Dth per day. Long-term firm transportation contracts for 133,100 Dth have been executed, some of which began in the third quarter 2010 and others that began in June 2011.

Line WB Expansion Project. The Gas Transmission and Storage Operations segment expanded its WB system through investment in additional facilities, which provide transportation service on a firm basis from Loudoun, Virginia to Leach, Kentucky. The expansion totaled approximately $14 million, allowing producers to meet incremental transportation demand in the Marcellus/Appalachian Basin. Binding precedent agreements for approximately 175,000 Dth per day of firm transportation capacity were executed, some which began in January 2011. Final construction on all facilities will be completed and placed into service in the first quarter of 2012.

East Lateral Project. In 2010, the Gas Transmission and Storage Operations segment initiated a $5 million project to modify existing facilities on the Columbia Gulf East Lateral to provide firm transportation service for up to 300,000 Dth per day. Firm transportation contracts for 250,000 Dth per day were executed for five-year terms. This FERC-approved project was completed and put into service in May 2011.

Southern Appalachian Project. The Gas Transmission and Storage Operations segment invested nearly $4 million to expand Line SM-116 to transport approximately 38,500 Dth per day on a firm basis as a continuation of its strategy to provide transportation services to producers of Marcellus and Appalachian gas. This additional capacity is supported by executed, binding precedent agreements. These additional facilities were placed in service in April 2011.

Power Plant Generation Project. The Gas Transmission and Storage Operations segment is planning to spend nearly $35 million on an expansion project, which includes new pipeline and modifications to existing compression assets, with Virginia Power Services Energy Corporation, Inc., the energy manager for Virginia Electric Power Company. This project will expand the Columbia Transmission system in order to provide up to nearly 250,000 Dth per day of transportation capacity under a long-term, firm contract. The project is expected to be ready for commercial operations by mid-2014.

Smithfield Project. The Gas Transmission and Storage Operations segment made approximately $14 million of capital investments for modifications to existing pipeline and compressor facilities to accommodate receipt of up to 150,000 Dth per day of additional Marcellus gas from connections near Smithfield, West Virginia and Waynesburg, Pennsylvania. Three anchor shippers agreed to long-term, firm transportation contracts, one contract that began in April 2011 and others that began in August 2011. The project is expected to be fully in service in the first quarter of 2012.

Rimersburg Expansion Project. The Gas Transmission and Storage Operations segment has approved an investment of approximately $6 million for this project that will add capacity to north central Pennsylvania to meet the growing demands of producers in the area. The project will consist of the expansion of Line 134 from the Brinker compressor station to the Iowa regulator, adding approximately 19,000 Dth per day of additional capacity, all of which has been sold through precedent agreements. The project is expected to go into service in the first quarter of 2012.

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NISOURCE INC.

Pennsylvania Marcellus Pipeline Project. The Gas Transmission and Storage Operations segment has approved an investment of approximately $150 million which will include right-of-way acquisitions and constructing new pipeline with an initial combined capacity of 300,000 Dth per day. Natural gas will initially be sourced from a new third-party processing plant and delivered to Columbia Transmission and two other third-party pipelines in Pennsylvania. The project is expected to be placed in service in late 2012.

Financial Management of the Balance Sheet

NiSource remains committed to maintaining its liquidity position through management of capital spending, working capital and operational requirements, and its financing needs. NiSource has executed on its plan by taking the following actions:

Credit Ratings. On December 13, 2011, Fitch affirmed the senior unsecured ratings for NiSource at BBB-, and the existing ratings of all other subsidiaries. Fitch’s outlook for NiSource and all of its subsidiaries is stable. On November 18, 2011, Moody’s Investors Service affirmed the senior unsecured ratings for NiSource at Baa3, and the existing ratings of all other subsidiaries. Moody’s outlook for NiSource and all of its subsidiaries is stable. On February 24, 2011, Standard & Poor’s affirmed the senior unsecured ratings for NiSource and its subsidiaries at BBB-. Standard & Poor’s outlook for NiSource and all of its subsidiaries is stable. Although all ratings continue to be investment grade, a downgrade by Standard & Poor’s, Moody’s or Fitch would result in a rating that is below investment grade.

Process and Expense Management

Refer to Note 3, “Impairments, Restructuring and Other Charges,” in the Notes to Consolidated Financial Statements for information on process and expense management.

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NISOURCE INC.

Ethics and Controls

NiSource has had a long term commitment to providing accurate and complete financial reporting as well as high standards for ethical behavior by its employees. NiSource’s senior management takes an active role in the development of this Form 10-K and the monitoring of the Company’s internal control structure and performance. In addition, NiSource will continue its mandatory ethics training program in which employees at every level throughout the organization participate.

Refer to “Management’s Report on Internal Control over Financial Reporting” included in Item 9A.

Results of Operations

The following information should be read taking into account the critical accounting policies applied by NiSource as discussed in “Other Information” of this Item 7.

Income from Continuing Operations and Net Income

For the twelve months ended December 31, 2011, NiSource reported income from continuing operations of $303.8 million, or $1.08 per basic share, compared to $285.2 million, or $1.03 per basic share in 2010. Income from continuing operations for the twelve months ended December 31, 2009 was $229.8 million, or $0.84 per basic share.

Including results from discontinued operations, NiSource reported 2011 net income of $299.1 million, or $1.06 per basic share, 2010 net income of $282.6 million, or $1.02 per basic share, and 2009 net income of $217.0 million, or $0.79 per basic share.

Comparability of line item operating results was impacted by regulatory and tax trackers that allow for the recovery in rates of certain costs such as bad debt expenses. Therefore, increases in these tracked operating expenses were offset by increases in net revenues and had essentially no impact on income from continuing operations. A decrease in operating expenses of $40.4 million for the 2011 year was offset by a corresponding decrease to net revenues reflecting these tracked costs. In the 2010 period, a decrease in operating expenses of $7.6 million for trackers was offset by a corresponding decrease to net revenues reflecting recovery of these costs. These changes from 2010 to 2011 were largely attributable to fluctuations in recoveries associated with low income assistance programs.

Immaterial Restatement

As discussed further below, NiSource is making certain correcting adjustments to its historical financial statements for the quarters of 2011 and 2010 and for the years of 2010 and 2009, as well as to other selected financial data for the years 2008 and 2007. NiSource does not believe these corrections are material individually or in the aggregate to its financial condition or its financial results for any reported period. Refer to the tables below for the effects of these corrections on prior periods.

Deferred revenue- In the fourth quarter of 2011, NiSource identified a deferred revenue regulatory asset of $25.2 million that was not recoverable. The impact of the correction in 2010 and 2009 resulted in a decrease in electric revenue of $7.4 million and an increase of $1.0 million, respectively, with an offset to deferred revenue regulatory assets. The remaining decrease in electric revenue of $18.2 million was corrected prior to 2009. The correction reduced electric revenue by a total of $0.6 million for previously reported interim periods in 2011. There was no impact to customers as a result of this correction.

Environmental asset recovery- NiSource recorded an out of period charge of $3.4 million in operation and maintenance expense and $4.6 million in depreciation and amortization expense in the first quarter of 2011 to impair a regulatory environmental asset that was not recoverable, which impairment charge should have been recorded in a prior year. The impact of the correction in 2010 and 2009 resulted in an increase to expense of $1.4 million and $1.0 million, respectively, with an offset to regulatory assets. The remaining increase to expense of $5.6 million was corrected prior to 2009.

OPEB over-reimbursement- In the fourth quarter of 2011, NiSource identified an over-reimbursement of $8.0 million received by NiSource from an insurer related to other post-employment benefits. The impact of the correction in 2010 and 2009 resulted in an increase in operation and maintenance expense of $1.0 million and $1.1 million, respectively, with an offset to other accruals. The remaining increase in expense of $5.4 million was corrected prior to 2009. The correction increased expense by a total of $0.5 million for previously reported interim periods in 2011.

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NISOURCE INC.

Environmental accrual- In the third quarter of 2010, NiSource recorded an out of period reduction to expense of $6.0 million to reduce an environmental liability that was incorrectly recorded in a prior year. To reverse the liability in the proper periods, NiSource recorded an increase in operation and maintenance expense of $6.0 million in 2010 and a decrease of $0.2 million in 2009 with an offset to legal and environmental accruals. The remaining decrease to expense of $5.8 million was corrected prior to 2009.

OPEB regulatory asset- NiSource recorded an out of period charge of $2.4 million in operation and maintenance expense in the second quarter of 2011 to impair a regulatory asset related to OPEB that was not probable of recovery, which impairment charge should have been recorded in a prior year. The impact of the correction in 2010 and 2009 resulted in a decrease to operation and maintenance expense of $0.2 million and an increase of $0.1 million, respectively, with an offset to regulatory assets. The remaining increase to expense of $2.3 million was corrected prior to 2009.

Healthcare claims- In 2008, NiSource recorded an out of period credit of $13.3 million to correct the allocation of healthcare claims expense to active employees and retired participants in its other post-employment benefits. As this error arose in 2007, NiSource is correcting the selected financial data for 2008 and 2007 for the impact of this error.

Unbilled revenue- In 2007, NiSource recorded an out of period charge of $25.5 million to correct an error that arose in prior years in its unbilled electric and gas revenue calculation. NiSource is correcting the selected financial data for 2007 for the impact of this error.

The following tables set forth the effects of the correcting adjustments to Net Income, for the years ended December 31, 2010, 2009, 2008 and 2007 and for the quarterly periods in 2011 and 2010:

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NISOURCE INC.

The following tables set forth the effects of the correcting adjustments on affected line items within NiSource’s previously reported Statements of Consolidated Income for the years ended December 31, 2010 and 2009, Consolidated Balance Sheets as of December 31, 2010 and the Statements of Consolidated Cash Flows for the years ended December 31, 2010 and 2009:

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NISOURCE INC.

Statements of Consolidated Cash Flows