Exhibit 99.3

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The Unaudited Pro Forma Condensed Combined Financial Statements (pro forma financial statements) have been derived from the historical consolidated financial statements of CenterPoint Energy, Inc. (CenterPoint Energy) and Vectren Corporation (Vectren). The following pro forma financial statements should be read in conjunction with:

On April 21, 2018, CenterPoint Energy entered into an Agreement and Plan of Merger (Merger Agreement), by and among CenterPoint Energy, Vectren and Pacer Merger Sub, Inc., an Indiana corporation and wholly owned subsidiary of CenterPoint Energy (Merger Sub). Pursuant to the Merger Agreement, on and subject to the terms and conditions set forth therein, Merger Sub will merge with and into Vectren (Vectren Merger), with Vectren continuing as the surviving corporation in the Vectren Merger and becoming a wholly owned subsidiary of CenterPoint Energy.

The Unaudited Pro Forma Condensed Combined Statements of Income (pro forma statements of income) for the six months ended June 30, 2018, and the year ended December 31, 2017, give effect to the Vectren Merger as if it were completed on January 1, 2017. The Unaudited Pro Forma Condensed Combined Balance Sheet (pro forma balance sheet) as of June 30, 2018, gives effect to the Vectren Merger as if it were completed on June 30, 2018.

The historical financial information has been adjusted in the pro forma financial statements to give effect to pro forma events that are (i) directly attributable to the Vectren Merger, (ii) factually supportable and (iii) with respect to the statements of income, expected to have a continuing impact on the combined results of CenterPoint Energy and Vectren.

The Vectren Merger will be accounted for as an acquisition of Vectren common shares by CenterPoint Energy and will follow the acquisition method of accounting for business combinations. The pro forma financial statements reflect an aggregate purchase price of approximately $6.0 billion in cash, based upon the “Merger Consideration” (as defined in the Merger Agreement) of $72.00 per share for each share of common stock of Vectren issued and outstanding immediately prior to the Vectren Merger.

CenterPoint Energy has obtained committed financing in the form of a $5.0 billion senior unsecured bridge term loan facility (Bridge Facility) from Goldman Sachs Bank USA and Morgan Stanley Senior Funding, Inc. Any borrowings under the Bridge Facility would be classified as short-term debt in current liabilities. CenterPoint Energy has prepared its pro forma financial statements in accordance with the applicable accounting rules assuming the aggregate purchase price will be financed by borrowings under the Bridge Facility and CenterPoint Energy’s existing revolving credit facility and the issuance by CenterPoint Energy of $500 million of its Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share (Series A Preferred Stock). However, CenterPoint Energy anticipates financing the Vectren Merger through its expected issuances of Series A Preferred Stock, common stock, mandatory convertible equity securities, debt securities and commercial paper, subject to then current market conditions, as well as cash on hand. CenterPoint Energy’s permanent financing assumptions are detailed in the accompanying notes.

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Assumptions and estimates underlying the pro forma adjustments are described in the accompanying notes, which should be read with the pro forma financial statements. Because the pro forma financial statements have been prepared on preliminary estimates, the total amounts recorded at the date of the Vectren Merger may differ materially from the information presented in the pro forma financial statements. These estimates are subject to change pending further review of the assets acquired and liabilities assumed in the Vectren Merger and the final purchase price of the Vectren Merger.

The pro forma financial statements have been presented for illustrative purposes only and are not necessarily indicative of the results of operations and financial position that would have been achieved had the pro forma events taken place on the dates indicated, or the future consolidated results of operations or financial position of the combined company.

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CENTERPOINT ENERGY, INC.

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

June 30, 2018

See Notes to Unaudited Pro Forma Condensed Combined Financial Statements

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CENTERPOINT ENERGY, INC.

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET — (continued)

June 30, 2018

See Notes to Unaudited Pro Forma Condensed Combined Financial Statements

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CENTERPOINT ENERGY, INC.

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME

For the Six Months Ended June 30, 2018

See Notes to Unaudited Pro Forma Condensed Combined Financial Statements

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CENTERPOINT ENERGY, INC.

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME

For the Year Ended December 31, 2017

See Notes to Unaudited Pro Forma Condensed Combined Financial Statements

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CENTERPOINT ENERGY, INC.

NOTES TO UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS

The pro forma statements of income for the six months ended June 30, 2018, and the year ended December 31, 2017, give effect to the Vectren Merger as if it were completed on January 1, 2017. The pro forma balance sheet as of June 30, 2018, gives effect to the Vectren Merger as if it were completed on June 30, 2018.

The pro forma financial statements have been derived from the historical consolidated financial statements of CenterPoint Energy and Vectren. Certain financial statement line items included in Vectren’s historical presentation have been reclassified to conform to corresponding financial statement line items included in CenterPoint Energy’s historical presentation (see Note 6). These reclassifications have no material impact on the historical operating income, net income, total assets, total liabilities or shareholders’ equity reported by CenterPoint Energy or Vectren. The historical consolidated financial statements have been adjusted in the pro forma financial statements to give effect to pro forma events that are (1) directly attributable to the business combination, (2) factually supportable and (3) with respect to the pro forma statements of income, expected to have a continuing impact on the combined results following the Vectren Merger.

Assumptions and estimates underlying the pro forma adjustments are described in these notes, which should be read in conjunction with the pro forma financial statements. Since the pro forma financial statements have been prepared based upon preliminary estimates, the final amounts recorded at the date of the Vectren Merger may differ materially from the information presented. These estimates are subject to change pending further review.

The Vectren Merger is reflected in the pro forma financial statements as an acquisition of Vectren by CenterPoint Energy, based on the guidance provided by accounting standards for business combinations. Under these accounting standards, the total estimated purchase price is allocated as described in Note 2 to the pro forma financial statements, and the assets acquired and the liabilities assumed have been measured at estimated fair value.

Vectren’s regulated operations are comprised of electric generation and electric and natural gas energy delivery services. These operations are subject to the rate-setting authority of the Federal Energy Regulatory Commission, the Indiana Utility Regulatory Commission and the Public Utilities Commission of Ohio, and are accounted for pursuant to U.S. generally accepted accounting principles, including the accounting guidance for regulated operations. The rate-setting and cost-recovery provisions currently in place for Vectren’s regulated operations provide revenue derived from costs including a return on investment of assets and liabilities included in rate base. Thus, the fair values of Vectren’s tangible and intangible assets and liabilities subject to these rate-setting provisions approximate their carrying values, and the pro forma financial statements do not reflect any net adjustments related to these amounts. Therefore, the excess purchase price over carrying value of net assets attributable to regulated operations is estimated to be compromised entirely of goodwill. The carrying values of Vectren’s non-regulated property, plant and equipment, which consists primarily of vehicles and equipment, and long-term debt, including the elimination of debt issuance costs, as of June 30, 2018, were reviewed and determined to approximate fair value; therefore, no fair value adjustment was reflected in the pro forma financial statements related to these balances.

The accounting policies used in the preparation of the pro forma financial statements are those described in CenterPoint Energy’s audited consolidated financial statements as of and for the year ended December 31, 2017. CenterPoint Energy performed a preliminary review of Vectren’s accounting policies to determine whether any adjustments were necessary to ensure comparability in the pro forma financial statements. At this time, CenterPoint Energy is not aware of any differences that would have a material effect on the pro forma financial statements, including any differences in the timing of adoption of new accounting standards, except for certain amounts that have been reclassified to conform to CenterPoint Energy’s financial statement

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presentation (see Note 6). Upon completion of the Vectren Merger, or as more information becomes available, CenterPoint Energy will perform a more detailed review of Vectren’s accounting policies. As a result of that review, differences may be identified between the accounting policies of the two companies that, when conformed, could have a material impact on the pro forma financial statements. The 2017 historical statements of income for CenterPoint Energy and Vectren do not reflect new accounting standards retrospectively adopted on January 1, 2018.

CenterPoint Energy reviewed the historical financial information for intercompany transactions and found no eliminations were necessary. Transaction costs recorded in the historical income statement have been excluded from the pro forma statements of income as they reflect nonrecurring charges directly related to the Vectren Merger. However, the transaction costs not recorded in the historical balance sheet are reflected in the pro forma balance sheet as an increase in other current liabilities and a decrease in retained earnings when such amounts are not reflected in the historical balance sheet.

The pro forma financial statements do not reflect the realization of any expected cost savings or other synergies from the Vectren Merger as a result of restructuring activities following the completion of the Vectren Merger. Certain of Vectren employment agreements contain severance or other termination arrangements; however, the pro forma financial statements do not reflect any such payments under these arrangements as employment decisions have not been finalized.

The estimated purchase price consideration of approximately $6.0 billion is based on the cash price of $72.00 per outstanding share of common stock of Vectren. The value of the purchase price consideration will change based on the actual number of shares of common stock of Vectren issued and outstanding immediately prior to the Vectren Merger.

CenterPoint Energy has performed a preliminary valuation analysis of the fair market value of Vectren’s assets and liabilities. The following table summarizes the allocation of the preliminary purchase price as of the acquisition date (in millions):

This preliminary purchase price allocation has been used to prepare pro forma adjustments in the pro forma balance sheet and income statement. CenterPoint Energy has not completed a final valuation analysis necessary to determine the fair market values of all of Vectren’s assets and liabilities or the allocation of its purchase price. The final allocation could differ materially from the preliminary allocation used in the pro forma adjustments. The final allocation may include (1) changes in fair values of property, plant and equipment, (2) changes in allocations to intangible assets and goodwill and (3) other changes to assets and liabilities.

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CenterPoint Energy sometimes refers to the planned issuance and sale of its common stock, mandatory convertible equity securities, Series A Preferred Stock, debt securities and commercial paper as described below (collectively, the Additional Financings). The actual size and terms of, and amounts of proceeds CenterPoint Energy receives from, the respective Additional Financings will depend on, among other things, market conditions at the time of the Additional Financings and such other factors as CenterPoint Energy deems relevant and may differ, perhaps substantially, from the size, terms and amounts CenterPoint Energy has assumed in this Note 3 to the pro forma financial statements.

As required by accounting rules and for purposes of the pro forma financial statements, CenterPoint Energy has assumed the following to fund the approximately $6.0 billion cash consideration purchase price further described below:

CenterPoint Energy obtained commitments by lenders for a $5.0 billion, 364-day Bridge Facility to provide flexibility for the timing of the acquisition financing and fund, in part, amounts payable by CenterPoint Energy in connection with the Vectren Merger. For purposes of the pro forma financial statements, CenterPoint Energy’s assumed borrowings under the Bridge Facility of $4.5 billion were reduced by the assumed issuance of $500 million of Series A Preferred Stock. For purposes of the pro forma financial statements, CenterPoint Energy has assumed a weighted-average interest rate of 5.3%, which includes duration and drawn fees on the $4.5 billion Bridge Facility borrowings. Drawn fees are estimated based on current 1-month LIBOR of 2.08% as of August 7, 2018, plus applicable margin under the Bridge Facility agreements. The Bridge Facility bears interest at an annual rate equal to LIBOR plus a margin ranging from 1.0% to 2.0%, depending on our credit rating, subject to an increase of 0.25% for each 90 days that elapse after the closing of the Vectren Merger. Assuming CenterPoint Energy, Inc.‘s current credit ratings, the applicable margin increases 0.25% each 90 days after the closing of the Vectren Merger, from 1.25% to a maximum of 2.00%. Upon execution of the Bridge Facility, CenterPoint Energy deferred debt issuance costs of $25 million in other assets, of which $7 million was amortized as debt issuance expense in the historical financial statements as of and for the six months ended June 30, 2018.

For purposes of the pro forma financial statements, CenterPoint Energy has presented the issuance of 500,000 shares of its Series A Preferred Stock for $492 million, net of $8 million of issuance costs and discounts, with an aggregate liquidation value of $500 million, and that those shares will require CenterPoint Energy to pay dividends in cash, calculated as a percentage of the aggregate liquidation value, at the rate of 6% per annum. This assumed dividend rate is based on current market conditions. The actual dividend rate on the Series A Preferred Stock at the time it is issued may differ, perhaps substantially, from the rate CenterPoint Energy has assumed for purposes of the pro forma financial statements. In addition, CenterPoint Energy has further assumed that none of the shares of the Series A Preferred Stock have been redeemed early by CenterPoint Energy during the periods presented in the pro forma financial statements.

In May 2018, CenterPoint Energy entered into an amendment to its revolving credit facility (as so amended, the Revolving Credit Facility) that will increase the aggregate commitments from $1.7 billion to $3.3 billion effective the earlier of (i) the termination of all commitments by certain lenders to provide the Bridge Facility and (ii) the payment in full of all obligations (other than contingent obligations) under the Bridge Facility and termination of all commitments to advance additional credit thereunder, and in each case, so long as the Merger Agreement has not been terminated pursuant to the terms thereof without consummation of the Vectren Merger. For purposes of the pro forma financial statements, CenterPoint Energy has assumed the balance of the purchase price consideration will be met by borrowings of approximately $1.0 billion under the Revolving Credit

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Facility at a weighted-average interest rate of 3.6%. Interest expense reflected in the pro forma financial statements includes arranger and commitments fees, as well as estimated interest on drawn amounts based on current 1-month LIBOR of 2.08% as of August 8, 2018, plus applicable rate under the Revolving Credit Facility, assuming current CenterPoint Energy, Inc. issuer credit ratings.

In lieu of borrowings under the Bridge Facility and the Revolving Credit Facility, CenterPoint Energy intends to execute the Additional Financings described below prior to the close of the Vectren Merger:

Because the Additional Financings are contemplated to take place in the future, the pro forma financial statements were prepared in accordance with the accounting rules assuming that the Merger Consideration will be financed from drawings under the Bridge Facility and under the Revolving Credit Facility and through the proceeds from the issuance of the Series A Preferred Stock. However, CenterPoint Energy currently does not intend to draw on the Bridge Facility or its Revolving Credit Facility but rather intends to fund the Merger Consideration with proceeds received through the Additional Financings, the proceeds from the issuance of the Series A Preferred Stock and cash on hand, although there is no guarantee that CenterPoint Energy will be able to consummate the Additional Financings as planned or at all.

The pro forma adjustments are based on our preliminary estimates and assumptions that are subject to change. The following adjustments have been reflected in the pro forma balance sheet:

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CenterPoint Energy has completed a preliminary review of the financial statement presentation of Vectren for purposes of the unaudited pro forma condensed combined financial statements. During this review, the following financial statement reclassifications were performed in order to align the presentation of Vectren’s financial information with that of CenterPoint Energy:

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