Exhibit 99.4

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The unaudited pro forma Condensed Consolidated Balance Sheet set forth below gives effect to the Dearborn Acquisition, the concurrent offerings by AK Steel Corporation (“AK Steel”) of its senior notes and AK Steel Holding Corporation (“AK Steel Holding” or the “Company”) of shares of its common stock and the application of the proceeds from both offerings (collectively referred to herein as the “Transactions”) as if they occurred on June 30, 2014, and the unaudited pro forma Condensed Consolidated Statements of Operations gives effect to the Transactions as if they had occurred at the beginning of each period. The unaudited pro forma condensed consolidated financial statements includes adjustments that give effect to events that are directly attributable to the Transactions and are expected to have a continuing effect and are factually supportable. The notes to the unaudited pro forma condensed consolidated financial statements describe the pro forma amounts and adjustments presented. The pro forma information is unaudited, are for informational purposes only and are not necessarily indicative of what our financial position or results of operations would have been had the Transactions been completed as of such dates and do not purport to represent what our financial position, results of operations or cash flows might be for any future period. In addition, the preparation of financial statements in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) requires management to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates and assumptions are preliminary and have been made solely for purposes of developing the unaudited pro forma condensed consolidated financial statements. Actual results could differ, perhaps materially, from these estimates and assumptions.

The Dearborn Acquisition will be accounted for using the acquisition method of accounting in accordance with U.S. GAAP and upon the assumptions set forth in the notes included in this section. The unaudited pro forma condensed consolidated financial statements reflect management’s preliminary valuation of assets acquired and liabilities assumed. The final allocation of the Dearborn Acquisition consideration will be based upon management’s consideration of valuation studies and post-closing purchase price adjustments. Any adjustments based on that final valuation may change the allocations of the Dearborn Acquisition consideration, which could affect the fair value assigned to the assets and liabilities and could result in a material change to the unaudited pro forma condensed consolidated financial statements. The unaudited pro forma condensed consolidated financial statements are primarily based on, and should also be read in conjunction with, the historical financial statements of AK Steel Holding and Severstal Dearborn, LLC.

As a result of a settlement agreement approved by the bankruptcy trustee of RG Steel, LLC on July 18, 2014, Dearborn became the 100% owner of Mountain State Carbon LLC (“Mountain State Carbon”). Prior to the settlement, Dearborn accounted for its 50% interest in Mountain State Carbon using the equity method. The unaudited pro forma condensed consolidated financial statements reflect the results of Mountain State Carbon as if it had been consolidated as of June 30, 2014 or the beginning of the period presented as applicable.

1

AK STEEL HOLDING CORPORATION

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET

June 30, 2014

(dollars in millions, except per share data)

2

AK STEEL HOLDING CORPORATION

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

YEAR ENDED DECEMBER 31, 2013

(dollars in millions, except per share data)

3

AK STEEL HOLDING CORPORATION

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

SIX MONTHS ENDED JUNE 30, 2014

(dollars in millions, except per share data)

4

AK STEEL HOLDING CORPORATION

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

TWELVE MONTHS ENDED JUNE 30, 2014

(dollars in millions, except per share data)

5

AK STEEL HOLDING CORPORATION

NOTES TO UNAUDITED PRO FORMA CONSOLIDATED FINANCIAL STATEMENTS

(dollars in millions)

Note A—Basis of Pro Forma Presentation

Assuming consummation of the Transactions on June 30, 2014, the purchase price of Dearborn (including Mountain State Carbon) would be allocated on a preliminary basis to the following assets and liabilities:

The preliminary allocation is based on a purchase price of $700.0, which will be paid in cash for the outstanding membership units of Dearborn at closing. The purchase price is subject to a working capital adjustment at closing.

For the purpose of preparing the unaudited pro forma condensed consolidated financial statements, the total estimated purchase price is allocated to Dearborn’s net tangible and intangible assets acquired and liabilities assumed as of the acquisition date. Final allocation of the purchase price will be based on the actual value of identifiable assets acquired and liabilities assumed in accordance with U.S. GAAP. Accordingly, the fair value of these identifiable assets and liabilities assumed included in the table above is preliminary and is subject to change. An allocation of an increased portion of the purchase price to inventory, property, plant and equipment, other non-current assets or intangible assets would result in increased depreciation and/or amortization expense. We expect to finalize the valuation and complete the purchase price allocation as soon as practical but no later than one year from the date of Dearborn Acquisition.

We estimate that the proceeds from both offerings, after deducting fees and estimated expenses, will be approximately $754.4 million. We intend to use the net proceeds from the offering by AK Steel of its senior notes, together with the net proceeds from the concurrent offering of AK Steel Holding’s shares of common stock, to finance the Dearborn Acquisition. We estimate the remaining proceeds from the offering of AK Steel Holding’s shares of common stock after payment for the Dearborn Acquisition and any fees and expenses related to the closing of the Dearborn Acquisition and the amendment of its Credit Facility to be $30.4 million, which will be used to repay outstanding borrowings under the Credit Facility.

Note B—Pro Forma Adjustments

6

7

8

The reduction in amortization expense is primarily a result of lower carrying values for long-term supply arrangements and changes in the fair value of the joint ventures investments.

9

10