Exhibit 99.1

KAPSTONE REPORTS FIRST QUARTER RESULTS

NORTHBROOK, IL — April 18, 2018 — KapStone Paper and Packaging Corporation (NYSE:KS) today reported results for the first quarter ended March 31, 2018. As compared to 2017’s first quarter, results for 2018’s first quarter are below:

·                  Net sales of $799 million up $33 million, or 4 percent

·                  Net income of $33 million up $27 million, or 446 percent

·                  Diluted EPS of $0.33 up $0.27 per share, or 450 percent

Non U.S. GAAP financial measures for the 2018 first quarter compared to 2017 are as follows:

·                  Adjusted EBITDA of $115 million up $34 million, or 42 percent

·                  Adjusted net income of $42 million up $27 million, or 181 percent

·                  Adjusted diluted EPS of $0.43 up $0.28 per share, or 187 percent

Matt Kaplan, President and Chief Executive Officer, stated, “Our first quarter results continued the positive momentum we built in the latter half of 2017.  Demand for containerboard, corrugated boxes, and kraft paper is strong.  We announced a $50 per ton containerboard price increase effective with shipments in mid-March.  In addition, we completed a rebuild of one of our boilers at the North Charleston mill which should provide for greater reliability and more efficient operations.

“Victory Packaging, our distribution business, had a solid first quarter and is entering its seasonally strongest quarter of the year.

“We continue to work on the merger with WestRock.”

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First Quarter Operating Highlights

Consolidated net sales of $799 million in the first quarter of 2018 increased by $33 million, or 4 percent compared to $766 million for the 2017 first quarter. The increase in net sales is primarily due to higher prices, partially offset by lower sales volume. The Company sold 662,000 tons of paper during the first quarter of 2018 compared to 699,000 tons a year earlier. Volume was lower in the current quarter as mill production was limited due to a boiler upgrade at the Charleston mill which reduced production by approximately 26,000 tons. The Company’s average mill selling price of $719 per ton in the first quarter of 2018 increased by $71 per ton, or about 11 percent compared to the first quarter of 2017 due to higher prices for most products and a favorable product mix. Mill selling prices increased by $21 per ton or 3 percent compared to the fourth quarter of 2017 due to higher specialty product prices and a better product mix.

Net income of $33 million for the 2018 first quarter increased by $27 million, or 446 percent, compared to the 2017 first quarter. The higher earnings primarily reflects:

·                  Higher selling prices and a better product mix of $48 million,

·                  Favorable productivity of $10 million mainly due to higher mill production,

·                  Lower recycled fiber costs of $6 million,

·                  Non-recurring 2017 costs of $5 million associated with ratifying a union contract at the North Charleston paper mill,

·                  A $7 million gain on the sale of the former Oakland box plant site, and

·                  A lower effective income tax rate resulting from the passage of the Tax Cuts and Jobs Act passed in December 2017.

The above items were partially offset by:

·                  Merger expenses of $14 million,

·                  Lower sales volume of $7 million,

·                  $8 million of higher planned maintenance costs, including the boiler upgrade,

·                  Inflation of $15 million driven by higher virgin fiber costs, freight and compensation,

·                  $4 million of weather related costs in January 2018, and

·                  Higher interest charges of $4 million due to higher interest rates.

Cash Flow and Working Capital

Cash and cash equivalents of $19 million as of March 31, 2018, declined by $9 million from December 31, 2017.  Operating activities provided $5 million during the first quarter. Investing activities used $22 million, including $37 million for capital expenditures, partially offset by $15 million of proceeds from the sale of the former Oakland box plant site. Financing activities provided $8 million of cash in the current quarter reflecting higher borrowings, partially offset by a quarterly dividend payment and the Victory Packaging contingent consideration payment.

On February 23, 2018, our Board of Directors approved a regular $0.10 per share cash dividend which was paid on April 11th.

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At March 31, 2018, the Company had approximately $431 million of working capital and $466 million of revolver borrowing capacity. The Company’s net debt to EBITDA ratio as defined by the bank agreement decreased to 2.96 times at March 31, 2018, down from 3.99 a year ago.

About the Company

Headquartered in Northbrook, IL, KapStone Paper and Packaging Corporation is the fifth largest producer of containerboard and corrugated packaging products and is the largest kraft paper producer in the United States. The Company has four paper mills, 23 converting plants and over 60 distribution centers. The business has approximately 6,300 employees.

Non-GAAP Financial Measures

This press release includes certain non-GAAP financial measures, including “EBITDA”, “Adjusted EBITDA”, “Adjusted Net Income”, and “Adjusted Diluted EPS” to measure our operating performance. Management uses these measures to focus on the on-going operations, and believes it is useful to investors because they enable them to perform meaningful comparisons of past and present operating results. The Company believes that EBITDA and Adjusted EBITDA provide useful information to investors because they improve the comparability of the financial results between periods and provide for greater transparency to key measures used to evaluate the performance of the Company. Management uses EBITDA and Adjusted EBITDA for evaluating the Company’s performance against competitors and as a primary measure for employees’ incentive programs. Reconciliations of Net Income to EBITDA, EBITDA to Adjusted EBITDA, Net Income to Adjusted Net Income, and Diluted EPS to Adjusted Diluted EPS are included in the financial schedules contained in this press release. However, these measures should not be construed as an alternative to any other measure of performance determined in accordance with GAAP.

Forward-Looking Statements

Statements in this news release that are not historical are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements can often be identified by words such as “may,” “will,” “should,” “would,’ “expect,” “project,” “anticipate,” “intend,” “plan,” “believe,” “estimate,” “potential,” “outlook,” or “continue,” the negative of these terms or other similar expressions. These statements reflect management’s current views and are subject to risks, uncertainties and assumptions, many of which are beyond the Company’s control that could cause actual results to differ materially from those expressed or implied in these statements. Factors that could cause actual results to differ materially include,

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but are not limited to: (1) industry conditions; (2) market and economic factors; (3) results of legal proceedings and compliance costs; (4) the ability to achieve and effectively manage growth; (5) the ability to pay the Company’s debt obligations; (6) the ability to carry out the Company’s strategic initiatives and manage associated costs; (7) managing labor relations; (8) realizing the synergies and benefits of strategic investments; (9) unanticipated business interruptions; and (10) various factors related to the pending transaction with WestRock, including but not limited to the ability of KapStone and WestRock to receive the required regulatory approvals (and the risk that such approvals may result in the imposition of conditions that could adversely affect the combined company or the expected benefits of the transaction), to receive the required approval of KapStone’s stockholders and to satisfy the other conditions to the closing of the proposed transaction on a timely basis or at all; the occurrence of events that may give rise to a right of one or both of the parties to terminate the merger agreement; negative effects of the announcement or the consummation of the proposed transaction on the market price of WestRock’s or KapStone’s common stock and/or on their respective businesses, financial conditions, results of operations and financial performance; risks relating to the value of the shares that may be issued in the transaction, significant transaction costs and/or unknown liabilities; the possibility that the anticipated benefits from the proposed transaction cannot be realized in full or at all or may take longer to realize than expected; risks associated with third party contracts containing consent and/or other provisions that may be triggered by the proposed transaction; risks associated with transaction-related litigation; the possibility that costs or difficulties related to the integration of KapStone’s operations with those of WestRock will be greater than expected; the outcome of legally required consultation with employees, their works councils or other employee representatives; and the ability of KapStone and the combined company to retain and hire key personnel. Further information on these and other risks and uncertainties is provided under Part I, Item 1A “Risk Factors” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 and elsewhere in reports that the Company files with the SEC. These filings can be found on KapStone’s Web site at http://www.kapstonepaper.com and the SEC’s Web site at www.sec.gov. Forward-looking statements included herein speak only as of the date hereof and the Company disclaims any obligation to revise or update such statements to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events or circumstances.

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KapStone Paper and Packaging Corporation

Consolidated Statements of Income

(In thousands, except share and per share amounts)

(Unaudited)

Supplemental Information

GAAP to Non-GAAP Reconciliations

($ in thousands, except share and per share amounts)

(unaudited)

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KapStone Paper and Packaging Corporation

Consolidated Balance Sheets

(In thousands)

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KapStone Paper and Packaging Corporation

Consolidated Statement of Cash Flows

(In thousands)

(Unaudited)

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KapStone Paper and Packaging Corporation

Operating Segment Information

(In thousands)

(Unaudited)

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KapStone Paper and Packaging Corporation

Operating Segment EBITDA and Adjusted EBITDA

(In thousands)

(Unaudited)

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KapStone Paper and Packaging Corporation

Summary of Interest Expense, net

(In thousands)

(Unaudited)

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