Strategic Merger with Akebia Therapeutics, Inc.	6 Months Ended
Jun. 30, 2018
Business Combinations [Abstract]
Strategic Merger with Akebia Therapeutics, Inc.	STRATEGIC MERGER WITH AKEBIA THERAPEUTICS, INC. Agreement and Plan of Merger On June 28, 2018, we entered into an agreement and plan of merger, or the Merger Agreement, with Akebia and Merger Sub, pursuant to which we will combine our respective businesses through the merger of Merger Sub with and into us, with our Company continuing after the Merger as the surviving corporation and a wholly-owned subsidiary of Akebia. The Merger Agreement has been approved by our Board of Directors and the board of directors of Akebia. At the effective time of the Merger, (i) each share of our common stock issued and outstanding immediately prior to the effective time of the Merger (other than the shares that are held by Akebia, Merger Sub, any subsidiary of Akebia or us, or held by us as treasury shares) will be converted into and become 0.37433 fully paid and non-assessable shares of common stock of Akebia, $0.00001 par value per share, each, an Akebia Share, such that the pre-Merger stockholders of us and Akebia will each own approximately 50% of the voting power of the combined company upon the closing of the Merger, which we refer to as the Combined Company, based on each of the companies’ fully diluted market capitalizations as of signing and before taking into account the 4.0 million additional shares issuable to Baupost described below. The Merger Agreement provides that, at the effective time of the Merger, each of our outstanding restricted shares issued under our equity incentive plans, which we refer to as Restricted Shares, other than those Restricted Shares that accelerate or lapse as a result of the Merger, will be canceled and converted into restricted stock unit awards of Akebia, the number of which will be adjusted in accordance with the terms of the Merger Agreement. Each of those Restricted Shares whose restrictions (including vesting) accelerate or lapse as a result of the Merger, will be canceled and converted into the right to receive 0.37433 Akebia Shares. In addition, each outstanding and unexercised option to acquire shares of our common stock granted under our equity incentive plans will be canceled and converted into an option to acquire Akebia Shares, with the number of shares and exercise price adjusted for the exchange ratio in accordance with the terms of the Merger Agreement. The Combined Company is expected to have a board of directors consisting initially of nine directors, comprised of: (i) four directors designated by the current board of directors of Akebia, each of whom will be a director of Akebia immediately prior to the date of the Merger Agreement (and who will be reasonably acceptable to us), referred to as the Akebia Directors; (ii) four directors designated by our current Board of Directors, each of whom will be a director of ours immediately prior to the date of the Merger Agreement (and who will be reasonably acceptable to Akebia), referred to as the Keryx Directors; and (iii) one additional director to be designated by our Board of Directors, who will serve as the chairperson and be reasonably acceptable to Akebia, referred to as the Additional Director. Alternatively, the Keryx Directors may choose to select the chairperson from amongst the Keryx Directors, who will be reasonably acceptable to Akebia, and in such an event such Keryx Director will serve as chairperson and the Akebia Directors and the Keryx Directors will select the Additional Director, who will be a person not on either the board of directors of Akebia or our Board of Directors as of the date of the Merger Agreement. We and Akebia each made certain representations and warranties, and agreed to certain covenants, in the Merger Agreement, including covenants by Akebia and us to conduct the respective businesses in the ordinary course during the period between the execution of the Merger Agreement and consummation of the Merger, to refrain from taking certain actions specified in the Merger Agreement and to use reasonable best efforts to cause the conditions of the Merger to be satisfied. The consummation of the Merger is subject to customary closing conditions, including: (i) approval of the issuance of Akebia Shares in connection with the Merger by the affirmative vote of the majority of Akebia Shares cast at the Akebia shareholders’ meeting in favor of the issuance of Akebia Shares in connection with the Merger; (ii) the adoption of the Merger Agreement by the affirmative vote of the holders of a majority of all outstanding shares of Keryx common stock entitled to vote thereon; (iii) the absence of any adverse law or order promulgated, entered, enforced, enacted or issued by any governmental entity that prohibits, restrains or makes illegal the consummation of the Merger; (iv) the Akebia Shares to be issued in the Merger being approved for listing on the Nasdaq Global Market; (v) the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and other material government approvals; (vi) subject to certain materiality exceptions, the accuracy of certain representations and warranties of each of us and Akebia contained in the Merger Agreement and the compliance by each party with the covenants contained in the Merger Agreement; and (vii) the absence of a material adverse effect with respect to each of us and Akebia. Akebia’s obligation to consummate the Merger is also subject to the conversion of the New Notes into shares of our common stock before the closing of the Merger pursuant to the Notes Conversion Agreement described below. We expect the Merger will be completed in the second half of 2018. The Merger Agreement contains certain termination rights for both us and Akebia, including for the failure to consummate the Merger by December 28, 2018, the enactment, promulgation or issuance of any injunction, order or ruling which has become final and non-appealable and makes the consummation of the Merger illegal or otherwise prohibits consummation of the Merger, failure of either our stockholders or Akebia’s stockholders to approve the Merger and related transactions, or breaches of representations, warranties or covenants by a party that result in the failure of certain conditions to closing being satisfied. In addition, each of us and Akebia have the right to terminate the Merger Agreement in order to enter into a “Superior Proposal” (as defined in the Merger Agreement). Upon termination of the Merger Agreement under certain specified circumstances Akebia or we may be required to pay the other party a termination fee of $22.0 million. Notes Conversion Transactions In connection with the Merger, we entered into a Notes Conversion Agreement, or the Conversion Agreement, with Baupost and, with respect to certain sections only, Akebia. Pursuant to the terms of the Conversion Agreement, Baupost has agreed to convert the New Notes into the 35.6 million shares of our common stock into which the New Notes are currently convertible, immediately prior to the effective time of the Merger, conditioned upon our issuance to Baupost of an additional 4.0 million shares of our common stock.

STRATEGIC MERGER WITH AKEBIA THERAPEUTICS, INC.

Agreement and Plan of Merger

On June 28, 2018, we entered into an agreement and plan of merger, or the Merger Agreement, with Akebia and Merger Sub, pursuant to which we will combine our respective businesses through the merger of Merger Sub with and into us, with our Company continuing after the Merger as the surviving corporation and a wholly-owned subsidiary of Akebia. The Merger Agreement has been approved by our Board of Directors and the board of directors of Akebia.

At the effective time of the Merger, (i) each share of our common stock issued and outstanding immediately prior to the effective time of the Merger (other than the shares that are held by Akebia, Merger Sub, any subsidiary of Akebia or us, or held by us as treasury shares) will be converted into and become 0.37433 fully paid and non-assessable shares of common stock of Akebia, $0.00001 par value per share, each, an Akebia Share, such that the pre-Merger stockholders of us and Akebia will each own approximately 50% of the voting power of the combined company upon the closing of the Merger, which we refer to as the Combined Company, based on each of the companies’ fully diluted market capitalizations as of signing and before taking into account the 4.0 million additional shares issuable to Baupost described below.

The Merger Agreement provides that, at the effective time of the Merger, each of our outstanding restricted shares issued under our equity incentive plans, which we refer to as Restricted Shares, other than those Restricted Shares that accelerate or lapse as a result of the Merger, will be canceled and converted into restricted stock unit awards of Akebia, the number of which will be adjusted in accordance with the terms of the Merger Agreement. Each of those Restricted Shares whose restrictions (including vesting) accelerate or lapse as a result of the Merger, will be canceled and converted into the right to receive 0.37433 Akebia Shares. In addition, each outstanding and unexercised option to acquire shares of our common stock granted under our equity incentive plans will be canceled and converted into an option to acquire Akebia Shares, with the number of shares and exercise price adjusted for the exchange ratio in accordance with the terms of the Merger Agreement.

The Combined Company is expected to have a board of directors consisting initially of nine directors, comprised of: (i) four directors designated by the current board of directors of Akebia, each of whom will be a director of Akebia immediately prior to the date of the Merger Agreement (and who will be reasonably acceptable to us), referred to as the Akebia Directors; (ii) four directors designated by our current Board of Directors, each of whom will be a director of ours immediately prior to the date of the Merger Agreement (and who will be reasonably acceptable to Akebia), referred to as the Keryx Directors; and (iii) one additional director to be designated by our Board of Directors, who will serve as the chairperson and be reasonably acceptable to Akebia, referred to as the Additional Director. Alternatively, the Keryx Directors may choose to select the chairperson from amongst the Keryx Directors, who will be reasonably acceptable to Akebia, and in such an event such Keryx Director will serve as chairperson and the Akebia Directors and the Keryx Directors will select the Additional Director, who will be a person not on either the board of directors of Akebia or our Board of Directors as of the date of the Merger Agreement.

We and Akebia each made certain representations and warranties, and agreed to certain covenants, in the Merger Agreement, including covenants by Akebia and us to conduct the respective businesses in the ordinary course during the period between the execution of the Merger Agreement and consummation of the Merger, to refrain from taking certain actions specified in the Merger Agreement and to use reasonable best efforts to cause the conditions of the Merger to be satisfied.

The consummation of the Merger is subject to customary closing conditions, including: (i) approval of the issuance of Akebia Shares in connection with the Merger by the affirmative vote of the majority of Akebia Shares cast at the Akebia shareholders’ meeting in favor of the issuance of Akebia Shares in connection with the Merger; (ii) the adoption of the Merger Agreement by the affirmative vote of the holders of a majority of all outstanding shares of Keryx common stock entitled to vote thereon; (iii) the absence of any adverse law or order promulgated, entered, enforced, enacted or issued by any governmental entity that prohibits, restrains or makes illegal the consummation of the Merger; (iv) the Akebia Shares to be issued in the Merger being approved for listing on the Nasdaq Global Market; (v) the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and other material government approvals; (vi) subject to certain materiality exceptions, the accuracy of certain representations and warranties of each of us and Akebia contained in the Merger Agreement and the compliance by each party with the covenants contained in the Merger Agreement; and (vii) the absence of a material adverse effect with respect to each of us and Akebia. Akebia’s obligation to consummate the Merger is also subject to the conversion of the New Notes into shares of our common stock before the closing of the Merger pursuant to the Notes Conversion Agreement described below. We expect the Merger will be completed in the second half of 2018.

The Merger Agreement contains certain termination rights for both us and Akebia, including for the failure to consummate the Merger by December 28, 2018, the enactment, promulgation or issuance of any injunction, order or ruling which has become final and non-appealable and makes the consummation of the Merger illegal or otherwise prohibits consummation of the Merger, failure of either our stockholders or Akebia’s stockholders to approve the Merger and related transactions, or breaches of representations, warranties or covenants by a party that result in the failure of certain conditions to closing being satisfied. In addition, each of us and Akebia have the right to terminate the Merger Agreement in order to enter into a “Superior Proposal” (as defined in the Merger Agreement). Upon termination of the Merger Agreement under certain specified circumstances Akebia or we may be required to pay the other party a termination fee of $22.0 million.

Notes Conversion Transactions

In connection with the Merger, we entered into a Notes Conversion Agreement, or the Conversion Agreement, with Baupost and, with respect to certain sections only, Akebia. Pursuant to the terms of the Conversion Agreement, Baupost has agreed to convert the New Notes into the 35.6 million shares of our common stock into which the New Notes are currently convertible, immediately prior to the effective time of the Merger, conditioned upon our issuance to Baupost of an additional 4.0 million shares of our common stock.