Exhibit 99.1

Unaudited Pro Forma Combined Condensed Consolidated Financial Information

The following unaudited pro forma combined condensed consolidated financial information combines the historical consolidated financial position and results of operations of KeyCorp and its subsidiaries and First Niagara Financial Group, Inc. (“First Niagara”) and its subsidiaries, as an acquisition by KeyCorp of First Niagara using the acquisition method of accounting and giving effect to the related pro forma adjustments described in the accompanying notes. Under the acquisition method of accounting, the assets and liabilities of First Niagara will be recorded by KeyCorp at their respective fair values as of the date the merger is completed. The unaudited pro forma combined financial information should be read in conjunction with KeyCorp’s Quarterly Report on Form 10-Q for the period ended March 31, 2016, and Annual Report on Form 10-K for the year ended December 31, 2015, and First Niagara’s Quarterly Report on Form 10-Q for the period ended March 31, 2016, and Annual Report on Form 10-K for the year ended December 31, 2015.

The merger was announced on October 30, 2015, and provides that each outstanding share of First Niagara common stock, par value $0.01 per share, held immediately prior to the merger will be canceled and converted into the right to receive 0.680 shares of KeyCorp common stock, par value $1.00 per share, and $2.30 in cash. The merger is intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code. Accordingly, a First Niagara stockholder who receives KeyCorp common shares and cash in exchange for First Niagara common stock pursuant to the merger will generally recognize gain (but not loss) in an amount equal to the lesser of (1) the amount by which the sum of the fair market value of the KeyCorp common shares and cash (other than cash received instead of a fractional KeyCorp common share) received by the First Niagara stockholder exceeds such holder’s tax basis in its First Niagara common stock, and (2) the amount of cash received by such First Niagara stockholder (except with respect to any cash received instead of fractional interests in KeyCorp common shares).

In addition, at the effective time of the merger, each share of First Niagara preferred stock, Series B, par value $0.01 per share, will be converted into the right to receive a share of a newly created series of preferred stock of KeyCorp having such rights, privileges and voting powers not materially less favorable to the holders thereof than the rights, preferences, privileges and voting powers of the First Niagara preferred stock.

On April 28, 2016, KeyCorp and First Niagara Financial Group, Inc. announced that they had reached an agreement with Northwest Bank, a wholly-owned subsidiary of Northwest Bancshares, Inc., to sell 18 branches in the Buffalo Federal Reserve market totaling $1.8 billion in deposits and $509 million in loans. Northwest Bank’s purchase includes all 18 branches slated for divestiture under Key’s agreements with the United States Department of Justice and the Federal Reserve Board, which were entered into in connection with their review of KeyCorp’s pending merger with First Niagara.

The unaudited pro forma combined condensed consolidated balance sheet gives effect to the merger and branch divestiture as if the transaction had occurred on March 31, 2016. The unaudited pro forma combined condensed consolidated income statements for the three months ended March 31, 2016, and the year ended December 31, 2015, give effect to the merger and branch divestiture as if the transaction had become effective on January 1, 2015.

The unaudited pro forma combined condensed consolidated financial information is presented for illustrative purposes only and does not indicate the financial results of the combined company had the companies actually been combined at the beginning of each period presented, nor the impact of possible business model changes. The unaudited pro forma combined condensed consolidated financial information also does not consider any potential effects of changes in market conditions on revenues, expense efficiencies, asset dispositions, and share repurchases, among other factors. In addition, as explained in more detail in the accompanying notes, the preliminary allocation of the pro forma purchase price reflected in the unaudited pro forma combined condensed consolidated financial information is subject to adjustment and may vary significantly from the actual purchase price allocation that will be recorded upon completion of the merger.

KeyCorp and Subsidiaries

Unaudited Pro Forma Combined Condensed Consolidated Balance Sheet

As of March 31, 2016

See accompanying notes to unaudited pro forma combined condensed consolidated financial statements.

KeyCorp and Subsidiaries

Unaudited Pro Forma Combined Condensed Consolidated Income Statement

For the three months ended March 31, 2016

See accompanying notes to unaudited pro forma combined condensed consolidated financial statements.

KeyCorp and Subsidiaries

Unaudited Pro Forma Combined Condensed Consolidated Income Statement

For the year ended December 31, 2015

See accompanying notes to unaudited pro forma combined condensed consolidated financial statements.

Note 1 – Basis of Presentation

The unaudited pro forma condensed combined consolidated financial information and explanatory notes have been prepared to illustrate the effects of the merger involving KeyCorp and First Niagara under the acquisition method of accounting with KeyCorp treated as the acquirer. The unaudited pro forma condensed combined consolidated financial information is presented for illustrative purposes only and does not necessarily indicate the financial results of the combined companies had the companies actually been combined at the beginning of each period presented, nor does it necessarily indicate the results of operations in future periods or the future financial position of the combined entity. Under the acquisition method of accounting, the assets and liabilities of First Niagara, as of the effective date of the merger, will be recorded by KeyCorp at their respective fair values and the excess of the merger consideration over the fair value of First Niagara’s net assets will be allocated to goodwill.

The merger, which is currently expected to be completed in the third quarter of 2016, provides for First Niagara common stockholders to right to receive 0.680 shares of KeyCorp common stock and $2.30 in cash for each share of First Niagara common stock they hold immediately prior to the merger. The value of the per share merger consideration would be approximately $11.40 based upon the closing price of KeyCorp common stock on October 29, 2015, multiplied by the exchange ratio, and adding the cash portion of the merger consideration. Based on the closing trading price of KeyCorp common shares on the NYSE on May 13, 2016, the last practicable date before the date of this current report on Form 8-K, the value of the merger consideration per share of First Niagara common stock was $10.24. In addition, at the effective time of the merger, each share of First Niagara preferred stock Series B will be converted into the right to receive a share of a newly created series of preferred stock of KeyCorp having such rights, preferences, privileges and voting powers not materially less favorable to the holders thereof than the rights, preferences, privileges and voting powers of the First Niagara preferred stock.

The pro forma allocation of purchase price reflected in the unaudited pro forma condensed combined consolidated financial information is subject to adjustment and may vary from the actual purchase price allocation that will be recorded at the time the merger is completed. Adjustments may include, but not be limited to, changes in (i) First Niagara’s balance sheet through the effective time of the merger; (ii) the aggregate value of merger consideration paid if the price of KeyCorp’s stock varies from the assumed $13.38 per share, which represents the closing share price of KeyCorp common stock on October 29, 2015; (iii) total merger related expenses if consummation and/or implementation costs vary from currently estimated amounts; and (iv) the underlying values of assets and liabilities if market conditions differ from current assumptions.

The accounting policies of both KeyCorp and First Niagara are in the process of being reviewed in detail. Upon completion of such review, conforming adjustments or financial statement reclassification may be determined.

Note 2 – Preliminary Purchase Price Allocation

The pro forma adjustments include the estimated purchase accounting entries to record the merger transaction. The excess of the purchase price over the fair value of net assets acquired, net of deferred taxes, is allocated to goodwill. Estimated fair value adjustments included in the pro forma financial statements are based upon available information and certain assumptions considered reasonable, and may be revised as additional information becomes available.

Core deposit and other intangible assets of $402 million are included in the pro forma adjustments separate from goodwill and amortized using the sum-of-the-years-digits method over ten years. When the actual amortization is recorded for periods following the merger closing, the straight line or sum-of-the-years-digits method will be used, and the period of amortization may differ. Goodwill totaling $1.434 billion is included in the pro forma adjustments and is not subject to amortization. The purchase price is contingent on KeyCorp’s price per common share at the date of close, which has not yet occurred. Accordingly, a 10% increase or decrease in KeyCorp’s most recently used price per common share would result in a corresponding goodwill adjustment of approximately $323 million.

The preliminary purchase price allocation is as follows:

Note 3 – Pro Forma Adjustments

The following pro forma adjustments have been reflected in the unaudited pro forma combined condensed consolidated financial information. All taxable adjustments were calculated using a 38.5% tax rate to arrive at deferred tax asset or liability adjustments. All adjustments are based on current assumptions and valuations, which are subject to change.

Note 4 – Estimated Cost Savings and Merger Integration Costs

KeyCorp expects to realize approximately $400 million, or 40% of First Niagara’s current noninterest expense, in annual pre-tax cost savings following the merger. Estimated cost savings is expected to be fully realized in fiscal year 2018 and is excluded from this pro forma analysis.

Merger- and integration-related costs are not included in the pro forma combined condensed consolidated statements of income since they will be recorded in the combined results of income as they are incurred prior to or after completion of the merger and are not indicative of what the historical results of the combined company would have been had the companies been actually combined during the periods presented. Merger- and integration-related costs are estimated to be $550 million pre-tax.

Note 5 – Divestiture of First Niagara Bank Branches

On April 28, 2016, KeyCorp and First Niagara Financial Group, Inc. announced that they had reached an agreement with Northwest Bank, a wholly-owned subsidiary of Northwest Bancshares, Inc., to sell 18 branches in the Buffalo Federal Reserve market. Northwest Bank’s purchase includes all 18 branches slated for divestiture under Key’s agreements with the United States Department of Justice and the Federal Reserve Board, which were entered into in connection with their review of KeyCorp’s pending merger with First Niagara. Key will retain its middle market, private banking, municipal and commercial real estate client relationships within this market. The divestiture transaction is subject to the completion of the merger of KeyCorp and First Niagara, which remains subject to regulatory approvals.