NISOURCE INC

APPENDIX B TO PROXY STATEMENT

AMENDED AND RESTATED NISOURCE INC.

EMPLOYEE STOCK PURCHASE PLAN

This Amended and Restated NiSource Inc. Employee Stock Purchase Plan (“ESPP” or “Plan”), adopted by the Board of Directors (“Board”) of NiSource Inc. (“NiSource”) as of January 25, 2024, provides eligible employees (referred to herein as “you”) of NiSource and its participating subsidiaries (as described below) with the opportunity to purchase shares of common stock of NiSource, $.01 par value (“Common Stock”), at a discount from market value through payroll deductions. The primary purposes of the Plan are to provide employees of NiSource and its participating subsidiaries an additional means of saving a portion of their earnings and to encourage employee ownership of Common Stock. Further information concerning the Plan, including the number of shares of Common Stock to be offered pursuant to the Plan, is set forth herein. The Plan, as amended and restated herein, will become effective upon stockholder approval of the Plan within 12 months following the date on which it was adopted by the Board.

1. WHAT IS THE PLAN?

The Plan offers a convenient and economical way for eligible employees of NiSource to initiate or increase their ownership of Common Stock. Once you are enrolled in the Plan, your payroll deductions will be used by Fidelity Investments to purchase Common Stock (both full and fractional shares) for you.

2. WHO MAY PARTICIPATE?

Participating companies are:

(1) NiSource; and

(2) those subsidiaries of NiSource whose boards of directors have adopted resolutions requesting participation in the Plan for their employees and whose requests are approved by the NiSource Benefits Committee.

You may participate if:

(1) you are an active employee of NiSource or a participating subsidiary; and

(2) you are either: (a) (i) a full-time employee, or (ii) a part-time employee whose customary employment is more than 20 hours per week and more than five months in any calendar year; or (b) if you are part-time employee whose customary employment is 20 hours or less per week, you are customarily employed by NiSource or a participating subsidiary for at least six months in any calendar year.

However, even if you qualify under these rules, you may not acquire any right to purchase Common Stock under the Plan if:

(1) immediately after participating, you would own at least 5% of the total combined voting power or value of all classes of stock of NiSource or any subsidiary including any stock which the employee may purchase under outstanding rights and options; or

(2) such right would permit you to purchase stock under this Plan or any similar employee stock purchase plan of NiSource with a fair market value of more than $25,000 in a calendar year.

3. HOW DOES THE PLAN OPERATE?

The Plan provides for four Savings Periods during each calendar year. Savings accumulated by you through payroll deductions will be used at the end of each Savings Period to purchase as many full and fractional shares of Common Stock as possible at the purchase price determined for that Savings Period.

4. WHAT ARE THE SAVINGS PERIODS?

Savings Periods are the three-month periods from January 1 to March 31, April 1 to June 30, July 1 to September 30 and October 1 to December 31. Each Savings Period includes all paydays within that period.

5. WHEN CAN I START MY PARTICIPATION IN THE PLAN?

You become eligible to participate in the Plan with respect to the first Savings Period commencing on or after the day on which you first meet the criteria listed in response to question 2. Whether or not you participate in the Plan is your decision.

6. IF I AM ELIGIBLE, HOW DO I ENROLL IN THE PLAN?

You may enroll at netbenefits.fidelity.com or by contacting a Fidelity Stock Plan Services Representative. As part of the enrollment process, you will establish a Fidelity Account® - an individual brokerage account, in order to manage your ESPP. You must also elect an amount that will be deducted from your paycheck to contribute towards the purchase of Common Stock. Fidelity will send your payroll deduction election to the NiSource Payroll Department so that your payroll deduction can be added to your payroll record. Your payroll deduction will begin as quickly as administratively possible. At the time that you enroll, or anytime thereafter, you can designate a beneficiary on your Fidelity Account. If you are a Plan participant at the time of your death, your Fidelity Account will be distributed to the beneficiaries designated by you. You can complete the beneficiary designation online at fidelity.com. Once you have successfully completed your beneficiary designation, you should receive confirmation by postal mail. Any payroll deductions that have not been used to purchase shares of Common Stock at the time of death will be paid to your estate in cash.

7. WHAT IS A PAYROLL ELECTION?

A payroll election directs your employer to deduct money from your pay in a specified amount while you are a participant in the Plan. The payroll election remains effective until you change your payroll election at netbenefits.fidelity.com or by calling a Fidelity Stock Plan Services Representative.

8. WHEN WILL THE PAYROLL DEDUCTIONS START AND IN WHAT AMOUNT MAY THEY BE MADE?

Your payroll deductions will begin as soon as administratively possible. Payroll deductions can be in any full dollar amounts, not less than $10 per regular pay period, and not more than $20,000 per calendar year.

9. WHAT IF I DECIDE TO CHANGE OR STOP MY PAYROLL DEDUCTION?

You may change or stop your payroll deduction at any time. To make this change, you must complete a new payroll election at netbenefits.fidelity.com or by calling a Fidelity Stock Plan Services Representative.

10. WHAT HAPPENS TO THE MONEY DEDUCTED FROM MY PAY?

Your payroll deductions will be credited to your NiSource Inc. Purchase Account (“Purchase Account”) under the Plan. On the last trading day of each Savings Period, the balance in your Purchase Account will be applied to purchase full and fractional shares of Common Stock as described in response to question 13. No interest is paid to any employee on the amounts accumulated in his or her Purchase Account under the Plan.

11. WHAT WILL BE THE PRICE OF SHARES PURCHASED UNDER THE PLAN?

The purchase price per share assigned to the Common Stock for any Savings Period will be 90% of the fair market value on the purchase date. For purposes of the Plan, fair market value is the closing price of the Common Stock on the New York Stock Exchange (“NYSE”) on the last trading day of the Savings Period.

Shares of Common Stock purchased under the Plan will come from treasury shares, authorized but unissued shares or open market purchases of Common Stock. You will pay no brokerage commissions, fees or service charges in connection with purchases of Common Stock under the Plan.

12. HOW MANY SHARES MAY BE PURCHASED BY PARTICIPANTS UNDER THE PLAN?

Under this Amended and Restated ESPP, the maximum number of shares of Common Stock that may be purchased in the future under the Plan is 1,491,241 as of January 25, 2024, pending approval of 1,300,000 of these shares by stockholders. This number may increase again in the future with stockholder approval. This number may also increase

B-2 | 2024 Proxy Statement or decrease proportionately, as appropriate, in the event of a future stock dividend, stock split or combination of Common Stock, spin-off, reorganization or recapitalization. If the number of shares remaining available for purchase under the Plan is not sufficient to satisfy all then outstanding purchase rights, the available shares will be apportioned among all participants on an equitable basis.

13. HOW MANY SHARES CAN I BUY IN EACH SAVINGS PERIOD?

The number of shares of Common Stock purchased by you during each Savings Period will be determined by dividing your Purchase Account balance by the purchase price per share for that Savings Period (the last trading day of the Savings Period). Shares will be allocated to four decimal places. The number of shares you can purchase will depend on the size of your payroll deductions and the fair market value of the Common Stock as of each purchase date. For example, if you have authorized deductions of $200.00 for the Savings Period and the fair market value of a share of Common Stock on the purchase date is $20.00, then your purchase price would be 90% of $20.00 or $18.00, and you would purchase 11.1111 shares of Common Stock ($200/$18.00). The number of shares purchased is also subject to an annual limit as indicated in question 14. You can estimate the number of shares that will be purchased with your contributions at netbenefits.fidelity.com. See answer to question 27.

14. IS THERE AN ANNUAL CONTRIBUTION LIMIT ON THE NUMBER OF SHARES PURCHASED?

The Internal Revenue Service limits purchases under an Employee Stock Purchase Plan to $25,000 worth of stock in any one calendar year, valued as of the first day of the Savings Period. Therefore, the Plan will multiply the value of the Common Stock on the first trading date of the Savings Period by the number of shares purchased at the end of the Savings Period and limit the total value of shares purchased for all Savings Periods in the calendar year to $25,000. Any payroll deduction amounts not used to purchase shares as a result of the contribution limit will be refunded.

15. CAN COMMON STOCK BE PURCHASED UNDER THE PLAN FOR CASH?

No. Common Stock can be purchased only through payroll deductions.

16. WHAT HAPPENS TO THE SHARES I PURCHASE?

The shares you purchase will be considered credited to you as of the close of business on the last day of each Savings Period. Your shares will be deposited into your Fidelity Account as soon as administratively possible following the purchase date.

17. HOW WILL SHARES PURCHASED UNDER THE PLAN BE REGISTERED?

The shares will be registered in “street name” at Fidelity. This means that your shares will be registered in the name of Fidelity and you will be designated as the beneficial owner.

18. HOW DO I SELL SHARES THAT I HAVE PURCHASED THROUGH THE PLAN?

Any shares held in your Fidelity Account can be sold by Fidelity at your direction. You will have the ability to place “real time” orders to sell your Common Stock (or any other brokerage order) during regular market hours. The proceeds from the sale of your shares will be deposited into your Fidelity Account. Any sale of shares in your Fidelity Account will be subject to commissions and fees governing that account, as outlined in the Brokerage Commission Schedule contained within the Customer Agreement that you will complete when you enroll. Please refer to the answer to question 20 or the Brokerage Commission Schedule contained within your Customer Agreement on Fidelity.com for further details. Commissions and fees are subject to change.

Fidelity also provides you the ability to place an order to sell your Common Stock, when and how you prefer. You can trade 24 hours a day online or using Fidelity's Automated Service Telephone (FAST®). You can also place your trade with a Fidelity Stock Plan Services Representative, excluding holidays of the New York Stock Exchange.

Certain restrictions are imposed by the Federal securities laws and NiSource policy on sales of Common Stock by officers and certain other employees. All other employees may sell Common Stock purchased under the Plan without any restrictions.

19. ARE THERE ANY RESTRICTIONS ON THE TRANSFER OF SHARES PURCHASED UNDER THE PLAN?

Any shares purchased under the Plan are restricted from transfer to another financial institution for a two-year period. However, in light of certain Federal tax requirements, each employee on entering the Plan agrees to notify NiSource if he or she disposes of any shares of Common Stock purchased under the Plan within two years after the purchase date. You are still eligible to sell shares during this two year holding period, however, under current law you will be subject to additional federal income tax. See answer to question 35.

20. WHAT IS THE COST TO PARTICIPATE IN THE PLAN?

There are no brokerage commissions, fees or service charges connected with Common Stock purchases. These costs are paid by NiSource. However, you will pay all costs incurred in the sale of shares in your Fidelity Account. All sales will be subject to commissions and fees governing your Fidelity Account, as outlined in the Brokerage Commission Schedule contained within the Customer Agreement. Please refer to your Customer Agreement on Fidelity.com for further details. Commissions and fees are subject to change.

You will also be charged a regulatory transaction fee per dollar of the total principal amount of the sale proceeds or a portion thereof. This regulatory fee is paid to the Securities and Exchange Commission (“SEC”) at the time of sale and is required for all equity trades. This regulatory transaction fee is subject to modification by the SEC.

21. CAN MY RIGHTS UNDER THE PLAN BE ASSIGNED OR TRANSFERRED TO ANOTHER PERSON?

No. Your rights under the Plan cannot be assigned or transferred to another person.

22. MAY I TERMINATE MY PARTICIPATION IN THE PLAN AT ANY TIME?

Yes. Further, your death, retirement or termination of employment with NiSource, or your cessation of eligibility as a participating employee, will be considered your automatic termination from participation in the Plan.

23. HOW DO I TERMINATE MY PARTICIPATION IN THE PLAN AND WHEN IS IT EFFECTIVE?

You can terminate your participation by changing your contribution to $0 on netbenefits.fidelity.com or by calling a Fidelity Stock Plan Services Representative. If you terminate your participation, Fidelity will inform NiSource to stop any future payroll deductions and to refund any payroll deductions in your Purchase Account that have not been used to purchase Common Stock. Your payroll deduction and refund will be made as soon as administratively possible on your payroll check.

24. WHAT HAPPENS WHEN I TERMINATE MY PARTICIPATION?

The shares of Common Stock will remain in your Fidelity Account until transferred or sold. You cannot transfer shares to another financial institution until two years after the date of purchase. You can sell shares at any time but the sale will be subject to additional federal income tax as described in question 35. The cost to sell shares is described in the answer to question 20.

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25. MAY I WITHDRAW THE CASH IN MY PURCHASE ACCOUNT OR SUSPEND MY PAYROLL DEDUCTIONS WITHOUT TERMINATING MY PARTICIPATION IN THE PLAN?

Withdrawing the cash balance credited to your Purchase Account does not terminate your participation in the Plan. However, it does discontinue your payroll deductions. To resume your payroll deductions, you will need to elect a new payroll deduction amount at netbenefits.fidelity.com.

26. WHAT HAPPENS IF I DIE, RETIRE, TERMINATE MY EMPLOYMENT OR OTHERWISE CEASE TO BE ELIGIBLE TO PARTICIPATE?

Upon the occurrence of such event, your participation in the Plan will stop. The cash balance in your Purchase Account will be refunded to you, or your estate in the event of your death. The shares of Common Stock will remain in your Fidelity Account or in the event of your death will be transferred to your designated beneficiary.

27. HOW DO I LEARN ABOUT THE STATUS OF MY PURCHASE AND FIDELITY ACCOUNTS?

Each payroll deduction will be shown on your pay stub. In addition, you will receive a monthly statement from Fidelity if you have any activity (purchase, sale, transfer or dividend reinvestment) in your Fidelity Account. Should you have no activity in your Fidelity Account, you will receive a quarterly statement. You will also receive confirmations for transactions that are made in your account. If you would prefer to receive information online, you can sign up for e-delivery at Fidelity.com. Even if you do not elect to sign up for e-delivery, you can access your statements and confirmation online at any time.

These statements contain information that is helpful for tax reporting and cost basis purposes; therefore, you should keep the statements until all shares of Common Stock purchased under the Plan and Fidelity Account have been disposed of and all tax obligations have been met. You can also access your Fidelity Account information at any time at netbenefits.fidelity.com. You will be able to view your accumulated contributions and estimate the number of shares that will be purchased with your contributions at any time. Once logged in, click on the link for the NiSource ESPP and select Estimate Purchase. There, you will see your total accumulated contributions for the current savings period and the estimated number of shares that will be purchased with your contributions. You will also receive all reports issued to stockholders of NiSource, including annual reports and proxy solicitation material.

28. WHO ADMINISTERS THE PLAN?

The Compensation and Human Capital Committee of the Board of NiSource is the Administrator of the Plan. However, should you have questions concerning the Plan, or your Fidelity Account you should contact Fidelity or NiSource Stockholder Services.

29. WHAT IS THE RESPONSIBILITY OF NISOURCE AND THE ADMINISTRATOR UNDER THE PLAN?

NiSource and the Administrator of the Plan will not be liable for any act done in good faith in connection with the Plan, or for any good faith omission to act, including, without limitation, any claim of liability arising out of failure to terminate a participant’s Purchase Account upon such participant’s death or retirement prior to the receipt of notice in writing of the event.

30. WHO INTERPRETS THE PLAN?

The Administrator of the Plan reserves the right to interpret the terms of the Plan, in his or her sole discretion.

31. HOW LONG WILL THE PLAN BE IN EFFECT?

Unless earlier terminated by the Board of NiSource, the Plan will terminate when the maximum number of shares of Common Stock available for sale under the Plan have been purchased. (See response to question 12.)

32. MAY THE PLAN BE TERMINATED OR AMENDED?

NiSource reserves the right to modify, suspend or terminate the Plan, by action of the Board of NiSource or its Compensation and Human Capital Committee, at such time designated by the Board or Compensation and Human Capital Committee, which in no event shall be earlier than the first day of any Savings Period in which such change is made. Notice of suspension, modification or termination will be given to all participants.

In no event, however, may the Board or the Compensation and Human Capital Committee amend the Plan to (i) materially adversely affect any rights outstanding under the Plan during the Savings Period in which such amendment is to be effective, (ii) increase the maximum number of shares of Common Stock which may be purchased under the Plan (except with the approval of the stockholders of NiSource, or as described in response to question 12), (iii) decrease the purchase price of the Common Stock below 90% of the fair market value, or (iv) adversely affect the qualification of the Plan under Section 423 of the Internal Revenue Code.

Upon termination of the Plan for any reason, the cash then credited to your Purchase Account will be refunded to you by the NiSource Payroll Department. All full and fractional shares of Common Stock held in your Fidelity Account will be available to you in your Fidelity Account.

33. HOW ARE MY RIGHTS UNDER THE PLAN AFFECTED BY EVENTS SUCH AS A DISSOLUTION, LIQUIDATION OR MERGER OF NISOURCE?

In the event of the proposed dissolution or liquidation of NiSource, any and all offerings under the Plan will terminate immediately prior to the consummation of such proposed action, unless otherwise provided by the Board. The Board may, in its sole discretion, declare that your right to purchase shares under the Plan will terminate as of a date fixed by the Board and give you the right to purchase shares of Common Stock under the Plan.

In the event of a proposed sale of all or substantially all of the assets of NiSource, or the merger of NiSource with or into another corporation (or a parent or subsidiary of another corporation) when NiSource is not the surviving corporation, any and all offerings under the Plan shall terminate immediately prior to the consummation of such proposed action, unless otherwise provided by the Board. The Board may, in the exercise of its sole discretion in such instances, and in lieu of assumption or substitution of the rights to purchase shares of Common Stock under the Plan by a successor corporation, provide that you will have the right to purchase shares under the Plan.

If the Board permits a share purchase under the Plan in lieu of the assumption or substitution of the right to purchase shares of Common Stock by a successor corporation in the event of a merger or sale of assets, the Board will notify you that the rights shall be fully exercisable for a period of ten (10) days from the date of such notice (or such other period of time as the Board shall determine), and the rights shall terminate upon the expiration of such period.

34. IS AN EMPLOYEE REQUIRED TO ENTER THE PLAN?

Absolutely not. Each employee who participates in the Plan does so on a strictly voluntary basis. Each employee should decide whether the purchase of shares is a wise investment for him or her. An employee may wish to consult a specialist in investment or tax matters before making his or her decision.

35. IS THE PLAN SUBJECT TO ANY PROVISIONS OF THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 (“ERISA”)?

The Plan is not subject to any provisions of ERISA.

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