UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

On July 27, 2025, Spire Inc. (“Spire” or the “Company”), a Missouri corporation, entered into an Asset Purchase Agreement (the “Purchase Agreement”) with Piedmont Natural Gas Company, Inc. (“Piedmont”), a North Carolina corporation and wholly owned subsidiary of Duke Energy Corporation (“Duke Energy”), pursuant to which Spire agreed to acquire 100% of Piedmont’s Tennessee natural gas local distribution company business (the “Acquired Business”) for cash consideration of $2.48 billion subject to customary adjustments for net working capital, regulatory assets and liabilities, and capital expenditures at closing (the “Acquisition”). On March 31, 2026, Spire completed the acquisition, subject to customary purchase price adjustments.

Contemporaneously with the execution of the Purchase Agreement, Spire entered into a commitment letter with Bank of Montreal and BMO Capital Markets Corp. (the “Commitment Parties”) pursuant to which the Commitment Parties committed to provide, subject to the terms and conditions therein, senior unsecured bridge term loan facilities in an aggregate principal amount of up to $2.48 billion, comprised of a Tranche A facility of up to $1.88 billion and a Tranche B facility of up to $600 million (together, the “Bridge Facilities”). The commitments under the Bridge Facilities were terminated in connection with the closing of the Acquisition.

For the purposes of the unaudited pro forma condensed combined financial statements, the Company has assumed that the funding consists of (i) proceeds from the $900 million aggregate principal amount of Series A of $450 million and Series B of $450 million junior subordinated notes issued on November 24, 2025, (ii) proceeds from the concurrent issuance at the closing of the Acquisition of senior unsecured notes (the “Senior Notes”) through a private placement in an aggregate principal amount of approximately $825 million pursuant to a master note purchase agreement dated December 17, 2025, consisting of $130 million due April 1, 2029; $160 million due April 1, 2031; $105 million due April 1, 2033; $250 million due April 1, 2036; and $180 million due April 1, 2038, (iii) proceeds of $800 million from a senior unsecured term loan entered into on March 26, 2026, consisting of a Tranche A facility of $600 million maturing on March 30, 2027 and a Tranche B facility of $200 million maturing on March 30, 2027, and (iv) approximately $47 million of net proceeds from the issuance on February 9, 2026 of $400 million aggregate principal amount Senior Notes due September 1, 2031 (collectively, the “Financing Transactions”). In addition, on March 30, 2026, Spire announced the sale of its gas marketing business, Spire Marketing Inc., for $215 million, subject to customary closing conditions, including regulatory approvals. The Company expects to use the net proceeds from the sale to repay borrowings incurred in connection with the Acquisition. The effects of this transaction are not reflected in the unaudited pro forma condensed combined financial information.

The Acquisition has satisfied the waiting period without objection under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. On September 10, 2025, Piedmont and Spire jointly filed applications with the Tennessee Public Utility Commission (the “TPUC”) and the Federal Energy Regulatory Commission (the “FERC”) to facilitate the transfer of Piedmont’s Tennessee utility operations to Spire. On October 31, 2025, the FERC approved the transfer of gas supply contracts to Spire. On March 16, 2026, the TPUC approved the transfer of utility services to Spire. After receiving all regulatory approvals, Spire completed the Acquisition on March 31, 2026, subject to customary purchase price adjustments as set forth in the Purchase Agreement.

The following unaudited pro forma condensed combined financial information reflects the Acquisition and the Financing Transactions as described above and has been prepared in accordance with Article 11 of Regulation S-X.

The unaudited pro forma condensed combined financial information has been prepared by the Company using the acquisition method of accounting in accordance with generally accepted accounting principles in the United States of America ("U.S. GAAP"), with Spire as the acquiring entity for accounting purposes, and reflects estimates and assumptions deemed appropriate by the Company’s management to give effect to the Acquisition and the Financing Transactions as if they had been completed on December 31, 2025, with respect to the unaudited pro forma condensed combined balance sheet, and on October 1, 2024, with respect to the unaudited pro forma condensed combined statements of income.

The unaudited pro forma condensed combined financial information includes adjustments that reflect the accounting for the Acquisition and the Financing Transactions in accordance with U.S. GAAP. Refer to the notes to the unaudited pro forma financial information for additional information regarding the basis of presentation and pro forma adjustments.

The unaudited pro forma condensed combined financial information is based on and should be read in conjunction with the following:

The unaudited pro forma condensed combined financial information has been prepared for illustrative purposes only and is not necessarily indicative of what the combined company’s financial position or results of operations actually would have been if the Acquisition and the Financing Transactions occurred as of the dates indicated. The unaudited pro forma condensed combined financial information also should not be considered indicative of the future results of operations or financial position of the combined company following the completion of the Acquisition, which will differ, perhaps materially, from those shown in this information. The unaudited pro forma adjustments represent the Spire management’s estimates based on information available as of the date of the unaudited pro forma condensed combined financial information and are subject to change as additional information becomes available and analyses are performed.

The Company estimated the fair value of the assets and liabilities of the Acquired Business based on a preliminary valuation. A final determination of the fair value of the acquired assets and assumed liabilities will be performed. Any changes in the fair values of the net assets or total purchase consideration as compared with the information shown in the unaudited pro forma condensed combined financial information may change the amount of the total purchase consideration allocated to goodwill and other assets and liabilities and may impact the combined company’s statements of operations; therefore the final purchase consideration allocation will be different, perhaps materially, than the preliminary purchase consideration allocation presented in the unaudited pro forma condensed combined financial information.

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

As of December 31, 2025

(In millions)

See accompanying notes to the condensed unaudited pro forma financial information.

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME

Three Months Ended December 31, 2025

(In millions, except per share data)

See accompanying notes to the condensed unaudited pro forma financial information.

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME

Fiscal Year Ended September 30, 2025

(In millions, except per share data)

See accompanying notes to the condensed unaudited pro forma financial information.

NOTES TO THE UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

Note 1 – Basis of Pro Forma Presentation

The unaudited pro forma condensed combined financial information has been prepared in accordance with Article 11 of Regulation S-X and should be read in conjunction with the accompanying notes. Spire’s 2025 fiscal year end is on September 30, 2025, while the Acquired Business’s fiscal year ended on December 31, 2025. As a result of the Acquired Business having a different fiscal period-end than Spire, the unaudited pro forma condensed combined financial information has been prepared as follows:

Refer to Note 2, Reclassification of Abbreviated Financial Statements of the Acquired Business, for further details on the aggregation of the historical financial statements of the Acquired Business.

The historical financial statements have been prepared in accordance with U.S. GAAP. The unaudited condensed combined pro forma financial statements have been prepared based on the aforementioned historical financial statements and the assumptions and adjustments as described in the subsequent Notes to the pro forma financial information. The pro forma adjustments are based upon reported available information and methodologies that management determined appropriate for the Acquisition and do not reflect the costs of any integration activities or benefits that may result from realization of future revenue growth or operational synergies expected to result from the Acquisition.

The accounting policies used in the preparation of the unaudited pro forma condensed combined financial information are those described in Spire’s unaudited consolidated financial statements as of and for the quarter ended December 31, 2025, and the audited consolidated financial statements as of and for the fiscal year ended September 30, 2025. Spire has performed a preliminary review of the Acquired Business’s accounting policies to determine if any adjustments were necessary to achieve comparability in the unaudited pro forma condensed combined financial information. Currently, Spire is not aware of any material differences between the accounting policies of Spire and the Acquired Business that would continue to exist subsequent to the application of acquisition accounting.

Reclassification adjustments have been made to the historical presentation of the Acquired Business to conform to the financial statement presentation of Spire for the unaudited pro forma condensed combined financial information. Refer to Note 2, Reclassification of Abbreviated Financial Statements of the Acquired Business for further details on the reclassification adjustments.

Accounting for the Acquisition

The unaudited pro forma condensed combined financial information has been prepared assuming the Acquisition is accounted for using the acquisition method of accounting under Accounting Standards Codification (“ASC”) 805, Business Combinations, (“ASC 805”) with Spire as the acquiring entity. In accordance with ASC 805, the purchase price of the Acquired Business is allocated to the underlying assets acquired and liabilities assumed based on their estimated fair values as of the closing of the Acquisition. The excess of the purchase price over the estimated fair values of the net assets acquired, if applicable, will be recorded as goodwill.

The pro forma adjustments represent management’s estimates based on information available as of the date of this filing and are subject to change as additional information becomes available and additional analyses are performed. For purposes of the unaudited pro forma condensed combined balance sheet, the estimated acquisition consideration has been allocated to the assets acquired and liabilities assumed of the Acquired Business based upon management’s preliminary estimate of their fair values. The Company has not completed

the valuation analysis and calculations in sufficient detail necessary to arrive at the required estimates of the fair value of the assets to be acquired or liabilities assumed. Accordingly, the purchase price allocation and related adjustments reflected in the unaudited pro forma condensed combined financial information is preliminary and subject to revision based on a final determination of fair value as additional information becomes available and as additional analyses are performed. The pro forma adjustments represent Spire management’s best estimates and are based upon currently available information and certain assumptions that Spire believes are reasonable under the circumstances. Refer to Note 3 Preliminary Fair Value Measurement of Purchase Price Allocation to Assets Acquired and Liabilities Assumed from the Acquisition, for further details on the preliminary purchase price allocation.

Accounting for the Financing Transactions

The Company obtained a commitment letter for a senior unsecured 364-day bridge term loan facility (the “Bridge Facilities”) of up to approximately $2.48 billion. Spire financed the Acquisition through debt securities prior to the closing of the Acquisition however for purposes of the pro forma combined statements, the Company has assumed the following:

On March 30, 2026, Spire announced the sale of its gas marketing business, Spire Marketing Inc., for $215 million, subject to customary closing conditions, including regulatory approvals. The proceeds from the sale are expected to be used to partially repay borrowings in connection with the acquisition. The effect of this probable disposition is not reflected as an adjustment in the pro forma financial information because it is a separate unrelated transaction that does not meet the significance thresholds requiring pro forma presentation under Article 11 of Regulation S-X.

The financing costs are recorded as a direct deduction from the carrying amount of the liability and amortized into interest expense over the terms of the Financing Transactions as if they had occurred on October 1, 2024. The Bridge Facilities commitment fees are expensed in the unaudited pro forma condensed combined statement of income for the fiscal year ended September 30, 2025, since these amounts were not used for the Acquisition.

Note 2 – Reclassification of Abbreviated Financial Statements of the Acquired Business

During the preparation of the unaudited pro forma condensed combined financial information, Spire’s management performed a preliminary analysis of the Acquired Business’s financial information to identify differences in financial statement presentation as compared to the presentation of Spire. Certain reclassification adjustments have been made to conform the Acquired Business’s historical financial statement presentation to Spire’s financial statement presentation. Following the closing of the Acquisition, the combined company will finalize its review of the reclassifications, which will be different, perhaps materially, from the amounts set forth in the unaudited pro forma condensed combined financial information presented herein.

The table below presents the unaudited statement of assets acquired and liabilities assumed of the Acquired Business as of December 31, 2025, giving pro forma effect to the presentation adjustments:

NOTES:

(1) To reclassify the Acquired Business’s historical Inventory balance to Inventory: Materials and supplies and Inventories: Natural Gas.

(2) To reclassify the Acquired Business’s historical cost of Property, Plant and Equipment to Utility Plant.

(3) To reclassify Accumulated depreciation and amortization to Utility Plant: Accumulated depreciation and amortization.

(4) Represents a balancing adjustment to equity for the acquired assets and assumed liabilities.

The table below presents the unaudited statement of revenues and direct expenses of the Acquired Business, giving pro forma effect to the presentation adjustments and reflecting the results for the quarter ended December 31, 2025, to align with Spire’s quarter-end:

NOTES:

(1) To reclassify the Acquired Business’s Revenues to Operating Revenues

The table below presents the unaudited statement of revenues and direct expenses of the Acquired Business, giving pro forma effect to the presentation adjustments and reflecting the results for the year ended September 30, 2025, to align with Spire’s fiscal year-end: