Exhibit 99.1

NORTHEAST UTILITIES

UNAUDITED PRO FORMA CONDENSED COMBINED CONSOLIDATED FINANCIAL STATEMENTS

Overview

On April 10, 2012, Northeast Utilities (NU) acquired 100 percent of the outstanding common shares of NSTAR. Pursuant to the terms and conditions of the Agreement and Plan of Merger, as amended, NSTAR merged into NSTAR LLC, becoming a wholly-owned subsidiary of NU. NSTAR LLC is a holding company engaged through its subsidiaries in the energy delivery business serving electric and natural gas distribution customers in Massachusetts. The merger was structured as a merger of equals in a tax-free exchange of shares. As part of the merger, NSTAR shareholders received 1.312 NU common shares for each NSTAR common share owned (the “exchange ratio”) as of the acquisition date. NU issued approximately 136 million common shares to the NSTAR shareholders as a result of the merger, which brought the total common shares outstanding to approximately 314 million shares as of April 10, 2012.

The Unaudited Pro Forma Condensed Combined Consolidated Financial Statements (pro forma financial statements) have been primarily derived from the historical consolidated financial statements of NU and NSTAR. The Unaudited Pro Forma Condensed Combined Consolidated Statements of Income (pro forma statements of income) for the six months ended June 30, 2012 and for the year ended December 31, 2011 give effect to the merger as if it were completed on January 1, 2011. The historical consolidated statement of income of NU for the six months ended June 30, 2012 includes NSTAR’s consolidated information for the period April 10, 2012 through June 30, 2012. The historical consolidated statement of income of NSTAR for the six months ended June 30, 2012 includes results for the period prior to the merger, January 1, 2012 through April 9, 2012. The pro forma adjustments in the pro forma financial statements were estimated using the merger closing date of April 10, 2012.

The merger of NU and NSTAR was accounted for as an acquisition of NSTAR by NU and has followed the acquisition method of accounting for business combinations. The purchase price was based on the closing price of NU common shares on the NYSE on April 9, 2012 of $36.79.

The historical consolidated financial information has been adjusted in the pro forma financial statements to give effect to events that are: (1) directly attributable to the merger; (2) factually supportable; and (3) with respect to the statements of income, expected to have a continuing impact on the combined results of NU. As the effects of this merger have been included in the unaudited condensed consolidated balance sheet as of June 30, 2012 filed in NU’s second quarter 2012 Quarterly Report on Form 10-Q, which is incorporated by reference herein, a pro forma combined balance sheet is not required or presented herein.

The pro forma financial statements reflect the amortization of purchase price adjustments assuming the merger had taken place on January 1, 2011. Assumptions and estimates underlying the pro forma adjustments are described in the accompanying notes, which should be read in connection with the pro forma financial statements. These estimates are subject to change pending further review of the assets acquired and liabilities assumed. The pro forma financial statements do not reflect any cost savings (or associated costs to achieve such savings) from operating efficiencies or synergies that could result from the merger.

The pro forma financial statements have been presented for illustrative purposes only and are not intended to be indicative of results of operations that would have been achieved had the merger been completed as of the date presented, or the future consolidated results of operations of NU after the merger.

The following pro forma financial statements should be read in conjunction with (1) the consolidated financial statements and notes thereto of NU for the year ended December 31, 2011, included in NU’s 2011 combined Annual Report on Form 10-K, (2) the unaudited condensed consolidated interim financial statements and notes thereto of NU as of and for the six months ended June 30, 2012, included in NU’s second quarter 2012 Quarterly Report on Form 10-Q, (3) the consolidated financial statements and notes thereto of NSTAR for the year ended December 31, 2011, included in NSTAR’s 2011 Annual Report on Form 10-K, and (4) the other information contained in or incorporated by reference into this document.

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NORTHEAST UTILITIES

UNAUDITED PRO FORMA CONDENSED COMBINED

CONSOLIDATED STATEMENT OF INCOME

For the Six Months Ended June 30, 2012

See accompanying Notes to the Unaudited Pro Forma Condensed Combined Consolidated Financial Statements which are an integral part of these statements.

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NORTHEAST UTILITIES

UNAUDITED PRO FORMA CONDENSED COMBINED

CONSOLIDATED STATEMENT OF INCOME

For the Year Ended December 31, 2011

See accompanying Notes to the Unaudited Pro Forma Condensed Combined Consolidated Financial Statements which are an integral part of these statements. Certain financial statement amounts included in NU’s and NSTAR’s historical income statement have been reclassified to conform to corresponding amounts included in NU’s current period presentation.

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NOTES TO THE UNAUDITED PRO FORMA CONDENSED

COMBINED CONSOLIDATED FINANCIAL STATEMENTS

Note 1. Basis of Presentation

See the accompanying Overview to the unaudited pro forma condensed combined consolidated financial statements for a description of the merger transaction and the overall presentation of the pro forma financial statements. The pro forma financial statements have been primarily derived from the historical consolidated financial statements of NU and NSTAR and do not reflect any cost savings (or associated costs to achieve such savings) from operating efficiencies or synergies that could result from the merger. The pro forma statements of income for the six months ended June 30, 2012 and for the year ended December 31, 2011 give effect to the merger as if it were completed on January 1, 2011. The historical consolidated statement of income of NU included in the pro forma statement of income for the six months ended June 30, 2012 includes NSTAR’s consolidated information for the period April 10, 2012 through June 30, 2012. The historical consolidated statement of income of NSTAR included in the pro forma statement of income for the six months ended June 30, 2012 includes NSTAR’s results for the period prior to the merger, January 1, 2012 through April 9, 2012. The pro forma adjustments included in the pro forma statement of income for the six months ended June 30, 2012 includes the amortization of purchase price adjustments assuming the merger had occurred on January 1, 2011. The pro forma adjustments in the pro forma financial statements were estimated using the merger closing date of April 10, 2012.

The first quarter 2012 results of NSTAR include certain charges incurred to establish a reserve against the regulatory asset related to Basic Service bad debt costs ($17 million) and increases in estimates with respect to the allowance for doubtful accounts, incurred but not reported claims on medical benefits, general and workers’ compensation liabilities and various compensation accruals ($16 million).

Merger-related transaction costs were accounted for as expenses in the period in which the costs were incurred. The historical income statements of NU and NSTAR presented in the pro forma statements of income included combined transaction and merger-related costs of $144.7 million before taxes ($90.6 million after taxes) for the six months ended June 30, 2012 and $23.9 million before taxes ($17.2 million after taxes) for the year ended December 31, 2011. A pro forma adjustment has been reflected to remove the impact of these costs from pro forma results because they are non-recurring charges directly related to the merger. Transaction and other merger costs incurred in connection with the merger have been excluded from the pro forma statements of income because they represent non-recurring charges directly related to the merger. These adjustments include charges recorded at the time of the merger related to rate settlement agreements with the Massachusetts Attorney General and the Massachusetts Department of Energy Resources (DOER) and the Connecticut Attorney General and the Connecticut Office of Consumer Counsel (OCC). The pro forma financial statements do not reflect the effects of future regulatory actions that may impact the pro forma financial statements.

The merger was reflected in the pro forma financial statements as an acquisition of NSTAR by NU, in accordance with accounting standards for business combinations. Under the acquisition method, the total purchase price has been calculated as described in Note 2, using the closing price of NU common shares on April 9, 2012. Certain assets acquired and liabilities assumed have been measured at estimated fair value as of the merger date, based on estimates and assumptions that NU management believes are reasonable. The estimated fair values have been determined based on accounting guidance for fair value measurements, which defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

NSTAR’s regulated operations consist of electric and gas distribution and transmission operations. These operations are subject to rate-setting authority of the Massachusetts Department of Public Utilities (DPU) and the Federal Energy Regulatory Commission (FERC), which generally allow for recovery of costs of service, including a carrying charge on most net assets and liabilities. For the net assets and liabilities earning a carrying charge, the carrying values approximate fair values, and pro forma adjustments are not required.

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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. These estimates are subject to change pending further review of the assets acquired and liabilities assumed.

Note 2. Purchase Price and Preliminary Allocation

Pursuant to the merger, all of the NSTAR common shares were exchanged at the fixed exchange ratio of 1.312 common shares of NU for each NSTAR common share. The total consideration transferred in the merger was based on the closing price of NU common shares on April 9, 2012, the day prior to the date the merger was completed, and was calculated as follows:

Certain of NSTAR’s stock-based compensation awards, including deferred shares, performance shares and all outstanding stock options, were replaced with NU awards using the exchange ratio upon consummation of the merger. In accordance with accounting guidance for business combinations, the portion of the fair value of these awards attributable to service provided prior to the merger is included in the purchase price as it represents consideration transferred in the merger.

The allocation of the total purchase price to the fair values of assets acquired and liabilities assumed includes pro forma adjustments to reflect the fair values of NSTAR’s assets and liabilities estimated as of the merger date. The preliminary allocation of the purchase price as of June 30, 2012 is as follows (in millions):

Note 3. Pro Forma Adjustments

The pro forma adjustments included in the pro forma financial statements are as follows:

Adjustments to Unaudited Pro Forma Financial Statements

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Adjustments to Unaudited Pro Forma Condensed Combined Consolidated Statements of Income

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