Document:

EX-10.10

 Exhibit 10.10 

RELYPSA, INC. 
 2013
EMPLOYEE STOCK PURCHASE PLAN 
 ARTICLE I. 

PURPOSE, SCOPE AND ADMINISTRATION OF THE PLAN 

1.1 Purpose and Scope. The purpose of the Relypsa, Inc. 2013 Employee Stock Purchase Plan, as it may be amended from time to time, (the
“Plan”) is to assist employees of Relypsa, Inc., a Delaware corporation, (the “Company”) and its Designated Subsidiaries in acquiring a stock ownership interest in the Company pursuant to a plan which is intended to
qualify as an “employee stock purchase plan” under Section 423 of the Code and to help such employees provide for their future security and to encourage them to remain in the employment of the Company and its Subsidiaries. 

ARTICLE II. 
 DEFINITIONS

 Whenever the following terms are used in the Plan, they shall have the meaning specified below unless the context clearly indicates
to the contrary. The singular pronoun shall include the plural where the context so indicates. 
 2.1 “Agent” means the
brokerage firm, bank or other financial institution, entity or person(s), if any, engaged, retained, appointed or authorized to act as the agent of the Company or an Employee with regard to the Plan. 

2.2 “Administrator” shall mean the Committee, or such individuals to which authority to administer the Plan has been
delegated under Section 7.1 hereof. 
 2.3 “Board” shall mean the Board of Directors of the Company. 

2.4 “Code” shall mean the Internal Revenue Code of 1986, as amended. 

2.5 “Committee” shall mean the Compensation Committee of the Board. 

2.6 “Common Stock” shall mean the Class A common stock of the Company, par value $0.001 per share (as such may be
redesignated from time to time). 
 2.7 “Company” shall have such meaning as set forth in Section 1.1 hereof. 

2.8 “Compensation” of an Employee shall mean the regular straight-time earnings or base salary and commissions paid to the
Employee from the Company on each Payday as compensation for services to the Company or any Designated Subsidiary, before deduction for any salary deferral contributions made by the Employee to any tax-qualified or nonqualified deferred compensation
plan, including overtime, shift differentials, vacation pay, salaried production schedule premiums, holiday pay, jury duty pay, funeral leave pay, paid time off, military pay, prior week adjustments and weekly bonus, but excluding education or
tuition reimbursements, imputed income arising under any group insurance or benefit program, travel 

 
expenses, business and moving reimbursements, income received in connection with any stock options, restricted stock, restricted stock units or other compensatory equity awards and all
contributions made by the Company or any Designated Subsidiary for the Employee’s benefit under any employee benefit plan now or hereafter established. Such Compensation shall be calculated before deduction of any income or employment tax
withholdings, but shall be withheld from the Employee’s net income. 
 2.9 “Designated Subsidiary” shall
mean each Subsidiary that have been designated by the Board or Committee from time to time in its sole discretion as eligible to participate in the Plan, including any Subsidiary in existence on the Effective Date and any Subsidiary formed or
acquired following the Effective Date, in accordance with Section 7.2 hereof. 
 2.10 “Effective Date” shall mean
immediately prior to the date on which the Company’s registration statement relating to its initial public offering becomes effective, provided that the Board has adopted the Plan prior to or on such date, subject to approval of the Plan
by the Company’s stockholders. 
 2.11 “Eligible Employee” shall mean an Employee who (a) is customarily
scheduled to work at least twenty (20) hours per week, (b) whose customary employment is more than five (5) months in a calendar year and (c) after the granting of the Option would not be deemed for purposes of
Section 423(b)(3) of the Code to possess five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or any Subsidiary. For purposes of clause (c), the rules of Section 424(d) of the
Code with regard to the attribution of stock ownership shall apply in determining the stock ownership of an individual, and stock which an Employee may purchase under outstanding options shall be treated as stock owned by the Employee.
Notwithstanding the foregoing, the Administrator may exclude from participation in the Plan as an Eligible Employee (x) any Employee that is a “highly compensated employee” of the Company or any Designated Subsidiary (within the
meaning of Section 414(q) of the Code), or that is such a “highly compensated employee” (A) with compensation above a specified level, (B) who is an officer and/or (C) is subject to the disclosure requirements of
Section 16(a) of the Exchange Act and/or (y) any Employee who is a citizen or resident of a foreign jurisdiction (without regard to whether they are also a citizen of the United States or a resident alien (within the meaning of
Section 7701(b)(1)(A) of the Code)) if either (i) the grant of the Option is prohibited under the laws of the jurisdiction governing such Employee, or (ii) compliance with the laws of the foreign jurisdiction would cause the Plan or
the Option to violate the requirements of Section 423 of the Code; provided that any exclusion in clauses (x), and/or (y) shall be applied in an identical manner under each Offering Period to all Employees of the Company and all
Designated Subsidiaries, in accordance with Treasury Regulation Section 1.423-2(e). 
 2.12 “Employee” shall mean any
person who renders services to the Company or a Designated Subsidiary in the status of an employee within the meaning of Section 3401(c) of the Code. “Employee” shall not include any director of the Company or a Designated Subsidiary
who does not render services to the Company or a Designated Subsidiary in the status of an employee within the meaning of Section 3401(c) of the Code. For purposes of the Plan, the 

  
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employment relationship shall be treated as continuing intact while the individual is on military leave, sick leave or other leave of absence approved by the Company or Designated Subsidiary and
meeting the requirements of Treasury Regulation Section 1.421-1(h)(2). Where the period of leave exceeds three (3) months, or such other period specified in Treasury Regulation Section 1.421-1(h)(2), and the individual’s right to
reemployment is not guaranteed either by statute or by contract, the employment relationship shall be deemed to have terminated on the first day immediately following such three (3)-month period, or such other period specified in Treasury Regulation
Section 1.421-1(h)(2). 
 2.13 “Enrollment Date” shall mean the first date of each Offering Period. 

2.14 “Exercise Date” shall mean the last Trading Day of each Offering Period, except as provided in Section 5.2 hereof.

 2.15 “Exchange Act” shall mean the Securities Exchange Act of 1934, as amended. 

2.16 “Fair Market Value” shall mean, as of any date, the value of Common Stock determined as follows: 

(a) If the Common Stock is (i) listed on any established securities exchange (such as the New York Stock Exchange, the NASDAQ Global
Market and the NASDAQ Global Select Market), (ii) listed on any national market system or (iii) listed, quoted or traded on any automated quotation system, its Fair Market Value shall be the closing sales price for a share of Common Stock
as quoted on such exchange or system for such date or, if there is no closing sales price for a share of Common Stock on the date in question, the closing sales price for a share of Stock on the last preceding date for which such quotation exists,
as reported in The Wall Street Journal or such other source as the Administrator deems reliable; 
 (b) If the Common Stock is not
listed on an established securities exchange, national market system or automated quotation system, but the Common Stock is regularly quoted by a recognized securities dealer, its Fair Market Value shall be the mean of the high bid and low asked
prices for such date or, if there are no high bid and low asked prices for a share of Common Stock on such date, the high bid and low asked prices for a share of Common Stock on the last preceding date for which such information exists, as reported
in The Wall Street Journal or such other source as the Administrator deems reliable; or 
 (c) If the Common Stock is neither listed
on an established securities exchange, national market system or automated quotation system nor regularly quoted by a recognized securities dealer, its Fair Market Value shall be established by the Administrator in good faith. 

2.17 “Grant Date” shall mean the first Trading Day of an Offering Period. 

2.18 “New Exercise Date” shall have such meaning as set forth in Section 5.2(b) hereof. 

  
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 2.19 “Offering Period” shall mean the shall mean the six (6)-month period
commencing on each March 1 and September 1 following the Effective Date, except as otherwise provided under Section 5.3 hereof; provided, however, that the first Offering Period commencing on or after the Effective Date
shall commence and end on the dates determined by the Administrator. The duration and timing of Offering Periods may be changed by the Board or Committee, in its sole discretion. In no event may an Offering Period exceed twenty-seven
(27) months. 
 2.20 “Option” shall mean the right to purchase shares of Common Stock pursuant to the Plan during each
Offering Period. 
 2.21 “Option Price” shall mean the purchase price of a share of Common Stock hereunder as provided in
Section 4.2 hereof. 
 2.22 “Parent” means any entity that is a parent corporation of the Company within the meaning
of Section 424 of the Code and the Treasury Regulations thereunder. 
 2.23 “Participant” shall mean any Eligible
Employee who elects to participate in the Plan. 
 2.24 “Payday” shall mean the regular and recurring established day for
payment of Compensation to an Employee of the Company or any Designated Subsidiary. 
 2.25 “Plan” shall have such meaning
as set forth in Section 1.1 hereof. 
 2.26 “Plan Account” shall mean a bookkeeping account established and maintained
by the Company in the name of each Participant. 
 2.27 “Section 423 Option” shall have such meaning as set forth in
Section 3.1(b) hereof. 
 2.28 “Subsidiary” shall mean any entity that is a subsidiary corporation of the Company
within the meaning of Section 424 of the Code and the Treasury Regulations thereunder. In addition, with respect to any sub-plans adopted under Section 7.1(d) hereof which are designed to be outside the scope of Section 423 of the
Code, Subsidiary shall include any corporate or noncorporate entity in which the Company has a direct or indirect equity interest or significant business relationship. 

2.29 “Trading Day” shall mean a day on which the principal securities exchange on which the Common Stock is listed is open
for trading or, if the Common Stock is not listed on a securities exchange, shall mean a business day, as determined by the Administrator in good faith. 

2.30 “Withdrawal Election” shall have such meaning as set forth in Section 6.1(a) hereof. 

  
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 ARTICLE III. 

PARTICIPATION 
 3.1
Eligibility. 
 (a) Any Eligible Employee who shall be employed by the Company or a Designated Subsidiary on a given Enrollment Date
for an Offering Period shall be eligible to participate in the Plan during such Offering Period, subject to the requirements of Articles IV and V hereof, and the limitations imposed by Section 423(b) of the Code and the Treasury Regulations
thereunder. 
 (b) No Eligible Employee shall be granted an Option under the Plan which permits the Participant’s rights to purchase
shares of Common Stock under the Plan, and to purchase stock under all other employee stock purchase plans of the Company, any Parent or any Subsidiary subject to the Section 423 of the Code (any such Option or other option, a “Section
423 Option”), to accrue at a rate which exceeds $25,000 of fair market value of such stock (determined at the time the Section 423 Option is granted) for each calendar year in which any Section 423 Option granted to the
Participant is outstanding at any time. For purposes of the limitation imposed by this subsection, 
 (i) the right to
purchase stock under a Section 423 Option accrues when the Section 423 Option (or any portion thereof) first becomes exercisable during the calendar year, 

(ii) the right to purchase stock under a Section 423 Option accrues at the rate provided in the Section 423 Option,
but in no case may such rate exceed $25,000 of fair market value of such stock (determined at the time such option is granted) for any one calendar year, and 

(iii) a right to purchase stock which has accrued under a Section 423 Option may not be carried over to any other
Section 423 Option; provided that Participants may carry forward amounts so accrued that represent a fractional share of stock and were withheld but not applied towards the purchase of Common Stock under an earlier Offering Period, and
may apply such amounts towards the purchase of additional shares of Common Stock under a subsequent Offering Period; provided further that any amounts so accrued that are in excess of a fractional share of stock will be refunded to such
Participant. 
 The limitation under this Section 3.1(b) shall be applied in accordance with Section 423(b)(8) of the Code and the Treasury
Regulations thereunder. 
 3.2 Election to Participate; Payroll Deductions 

(a) Except as provided in Section 3.3 hereof, an Eligible Employee may become a Participant in the Plan only by means of payroll
deduction. Each individual who is an Eligible Employee as of an Offering Period’s Enrollment Date may elect to participate in such Offering Period and the Plan by delivering to the Company a payroll deduction

  
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authorization no later than the tenth (10th) calendar day prior to the applicable Enrollment Date. 

(b) Subject to Section 3.1(b) hereof, payroll deductions expressed as a whole number percentage and shall be equal to at least one
percent (1%) of the Participant’s Compensation as of each Payday of the Offering Period following the Enrollment Date, but not more than the lesser of fifteen percent (15%) of the Participant’s Compensation as of each Payday of
the Offering Period following the Enrollment Date. Amounts deducted from a Participant’s Compensation with respect to an Offering Period pursuant to this Section 3.2 shall be deducted each Payday through payroll deduction and credited to
the Participant’s Plan Account. 
 (c) Following at least one (1) payroll deduction, a Participant may decrease (to as low as
zero) the amount deducted from such Participant’s Compensation only once during an Offering Period upon ten (10) calendar days’ prior written notice to the Company. A Participant may not increase the amount deducted from such
Participant’s Compensation during an Offering Period. 
 (d) Notwithstanding the foregoing, upon the termination of an Offering Period,
each Participant in such Offering Period shall automatically participate in the immediately following Offering Period at the same payroll deduction percentage as in effect at the termination of the prior Offering Period, unless such Participant
delivers to the Company a different election with respect to the successive Offering Period in accordance with Section 3.1(a) hereof, or unless such Participant becomes ineligible for participation in the Plan. 

3.3 Leave of Absence. During leaves of absence approved by the Company meeting the requirements of Treasury Regulation
Section 1.421-1(h)(2) under the Code, a Participant may continue participation in the Plan by making cash payments to the Company on his or her normal payday equal to his or her authorized payroll deduction. 

ARTICLE IV. 
 PURCHASE OF
SHARES 
 4.1 Grant of Option. Each Participant shall be granted an Option with respect to an Offering Period on the applicable
Grant Date. Subject to the limitations of Section 3.1(b) hereof, the number of shares of Common Stock subject to a Participant’s Option shall be determined by dividing (a) such Participant’s payroll deductions accumulated prior
to such Exercise Date and retained in the Participant’s Plan Account on such Exercise Date by (b) the applicable Option Price; provided that in no event shall a Participant be permitted to purchase during each Offering Period more
than 20,000 shares of Common Stock (subject to any adjustment pursuant to Section 5.2 hereof). The Administrator may, for future Offering Periods, increase or decrease, in its absolute discretion, the maximum number of shares of Common Stock
that a Participant may purchase during such future Offering Periods. Each Option shall expire on the Exercise Date for the applicable Offering Period immediately after the automatic exercise of the Option in accordance with Section 4.3 hereof,
unless such Option terminates earlier in accordance with Article 6 hereof. The share number in this Section 4.1 reflects the 17.2-to-1 reverse stock split that will be effective as of the day following the Effective Date, and shall not be further
adjusted for such reverse stock split. 

  
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 4.2 Option Price. The Option Price per share of Common Stock to be paid by a Participant
upon exercise of the Participant’s Option on the applicable Exercise Date for an Offering Period shall be equal to eighty five percent (85%) of the lesser of the Fair Market Value of a share of Common Stock on (a) the applicable Grant
Date and (b) the applicable Exercise Date; provided that in no event shall the Option Price per share of Common Stock be less than the par value per share of the Common Stock. 

4.3 Purchase of Shares. 

(a) On the applicable Exercise Date for an Offering Period, each Participant shall automatically and without any action on such
Participant’s part be deemed to have exercised his or her Option to purchase at the applicable Option Price the largest number of whole shares of Common Stock which can be purchased with the amount in the Participant’s Plan Account. The
balance, if any, remaining in the Participant’s Plan Account (after exercise of such Participant’s Option) as of such Exercise Date shall be carried forward to the next Offering Period, unless the Participant has elected to withdraw from
the Plan pursuant to Section 6.1 hereof or, pursuant to Section 6.2 hereof, such Participant has ceased to be an Eligible Employee. 

(b) As soon as practicable following the applicable Exercise Date, the number of shares of Common Stock purchased by such Participant pursuant
to Section 4.3(a) hereof shall be delivered (either in share certificate or book entry form), in the Company’s sole discretion, to either (i) the Participant or (ii) an account established in the Participant’s name at a
stock brokerage or other financial services firm designated by the Company. If the Company is required to obtain from any commission or agency authority to issue any such shares of Common Stock, the Company shall seek to obtain such authority.
Inability of the Company to obtain from any such commission or agency authority which counsel for the Company deems necessary for the lawful issuance of any such shares shall relieve the Company from liability to any Participant except to refund to
the Participant such Participant’s Plan Account balance, without interest thereon. 
 4.4 Transferability of Rights. 

(a) An Option granted under the Plan shall not be transferable, other than by will or the applicable laws of descent and distribution, and is
exercisable during the Participant’s lifetime only by the Participant. No option or interest or right to the Option shall be available to pay off any debts, contracts or engagements of the Participant or his or her successors in interest or
shall be subject to disposition by pledge, encumbrance, assignment or any other means whether such disposition be voluntary or involuntary or by operation of law by judgment, levy, attachment, garnishment or any other legal or equitable proceedings
(including bankruptcy), and any attempt at disposition of the option shall have no effect. 
 (b) Subject to Sections 5.2(b) and 5.2(c)
below, the Administrator may impose a holding period for the shares of Common Stock issued pursuant to the exercise of an Option. 

  
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 ARTICLE V. 

PROVISIONS RELATING TO COMMON STOCK 

5.1 Common Stock Reserved. Subject to adjustment as provided in Section 5.2 hereof, the maximum number of shares of Common Stock
that shall be made available for sale under the Plan shall be equal to the sum of (a) 255,317 shares of Common Stock and (b) an annual increase on the first day of each year beginning in 2014 and ending in 2023, equal to the least of
(i) 510,634 shares of Common Stock, (ii) one percent (1.0%) of the shares of Common Stock outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (iii) such number of shares of Common
Stock as determined by the Board. Shares of Common Stock made available for sale under the Plan may be authorized but unissued shares, treasury shares of Common Stock, or reacquired shares reserved for issuance under the Plan. The share numbers in
this Section 5.1 reflect the 17.2-to-1 reverse stock split that will be effective the day after the Effective Date, and shall not be further adjusted for such reverse stock split. 

5.2 Adjustments Upon Changes in Capitalization, Dissolution, Liquidation, Merger or Asset Sale. 

(a) Changes in Capitalization. Subject to any required action by the stockholders of the Company, the number of shares of Common Stock
which have been authorized for issuance under the Plan but not yet placed under Option, as well as the price per share and the number of shares of Common Stock covered by each Option under the Plan which has not yet been exercised shall be
proportionately adjusted for any increase or decrease in the number of issued shares of Common Stock resulting from a stock split, reverse stock split, stock dividend, combination or reclassification of the Common Stock, or any other increase or
decrease in the number of shares of Common Stock effected without receipt of consideration by the Company; provided, however, that conversion of any convertible securities of the Company shall not be deemed to have been “effected
without receipt of consideration.” Such adjustment shall be made by the Administrator, whose determination in that respect shall be final, binding and conclusive. Except as expressly provided herein, no issuance by the Company of shares of
stock of any class, or securities convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number or price of shares of Common Stock subject to an Option. 

(b) Dissolution or Liquidation. In the event of the proposed dissolution or liquidation of the Company, the Offering Period then in
progress shall be shortened by setting a new Exercise Date (the “New Exercise Date”), and shall terminate immediately prior to the consummation of such proposed dissolution or liquidation, unless provided otherwise by the
Administrator. The New Exercise Date shall be before the date of the Company’s proposed dissolution or liquidation. The Administrator shall notify each Participant in writing, at least ten (10) business days prior to the New Exercise Date,
that the Exercise Date for the Participant’s Option has been changed to the New Exercise Date and that the Participant’s Option shall be exercised automatically on the New Exercise Date, unless prior to such date the Participant has
withdrawn from the Offering Period as provided in Section 6.1 hereof. 

  
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 (c) Merger or Asset Sale. In the event of a proposed sale of all or substantially all of
the assets of the Company, or the merger of the Company with or into another corporation, each outstanding Option shall be assumed or an equivalent Option substituted by the successor corporation or a Parent or Subsidiary of the successor
corporation. In the event that the successor corporation refuses to assume or substitute for the Option, any Offering Periods then in progress shall be shortened by setting a New Exercise Date and any Offering Periods then in progress shall end on
the New Exercise Date. The New Exercise Date shall be before the date of the Company’s proposed sale or merger. The Administrator shall notify each Participant in writing, at least ten (10) business days prior to the New Exercise Date,
that the Exercise Date for the Participant’s Option has been changed to the New Exercise Date and that the Participant’s Option shall be exercised automatically on the New Exercise Date, unless prior to such date the Participant has
withdrawn from the Offering Period as provided in Section 6.1 hereof. 
 5.3 Insufficient Shares. If the Administrator
determines that, on a given Exercise Date, the number of shares of Common Stock with respect to which Options are to be exercised may exceed the number of shares of Common Stock remaining available for sale under the Plan on such Exercise Date, the
Administrator shall make a pro rata allocation of the shares of Common Stock available for issuance on such Exercise Date in as uniform a manner as shall be practicable and as it shall determine in its sole discretion to be equitable among all
Participants exercising Options to purchase Common Stock on such Exercise Date, and unless additional shares are authorized for issuance under the Plan, no further Offering Periods shall take place and the Plan shall terminate pursuant to
Section 7.5 hereof. If an Offering Period is so terminated, then the balance of the amount credited to the Participant’s Plan Account which has not been applied to the purchase of shares of Common Stock shall be paid to such Participant in
one lump sum in cash within thirty (30) days after such Exercise Date, without any interest thereon. 
 5.4 Rights as
Stockholders. With respect to shares of Common Stock subject to an Option, a Participant shall not be deemed to be a stockholder of the Company and shall not have any of the rights or privileges of a stockholder. A Participant shall have the
rights and privileges of a stockholder of the Company when, but not until, shares of Common Stock have been deposited in the designated brokerage account following exercise of his or her Option. 

ARTICLE VI. 
 TERMINATION
OF PARTICIPATION 
 6.1 Cessation of Contributions; Voluntary Withdrawal. 

(a) A Participant may cease payroll deductions during an Offering Period and elect to withdraw from the Plan by delivering written notice of
such election to the Company in such form and at such time prior to the Exercise Date for such Offering Period as may be established by the Administrator (a “Withdrawal Election”). A Participant electing to withdraw from the Plan
may elect to either (i) withdraw all of the funds then credited to the Participant’s Plan Account as of the date on which the Withdrawal Election is received by the Company, in which case amounts credited to such Plan Account shall be
returned to the Participant in one (1) lump-sum payment in cash within thirty (30) days after such election is 

  
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received by the Company, without any interest thereon, and the Participant shall cease to participate in the Plan and the Participant’s Option for such Offering Period shall terminate; or
(ii) exercise the Option for the maximum number of whole shares of Common Stock on the applicable Exercise Date with any remaining Plan Account balance returned to the Participant in one (1) lump-sum payment in cash within thirty
(30) days after such Exercise Date, without any interest thereon, and after such exercise cease to participate in the Plan. Upon receipt of a Withdrawal Election, the Participant’s payroll deduction authorization and his or her Option to
purchase under the Plan shall terminate. 
 (b) A participant’s withdrawal from the Plan shall not have any effect upon his or her
eligibility to participate in any similar plan which may hereafter be adopted by the Company or in succeeding Offering Periods which commence after the termination of the Offering Period from which the Participant withdraws. 

(c) A Participant who ceases contributions to the Plan during any Offering Period shall not be permitted to resume contributions to the Plan
during that Offering Period. 
 6.2 Termination of Eligibility. Upon a Participant’s ceasing to be an Eligible Employee, for any
reason, such Participant’s Option for the applicable Offering Period shall automatically terminate, he or she shall be deemed to have elected to withdraw from the Plan, and such Participant’s Plan Account shall be paid to such Participant
or, in the case of his or her death, to the person or persons entitled thereto pursuant to applicable law, within thirty (30) days after such cessation of being an Eligible Employee, without any interest thereon. 

ARTICLE VII. 
 GENERAL
PROVISIONS 
 7.1 Administration. 

(a) The Plan shall be administered by the Committee, which shall be composed of members of the Board. The Committee may delegate
administrative tasks under the Plan to the services of an Agent and/or Employees to assist in the administration of the Plan, including establishing and maintaining an individual securities account under the Plan for each Participant. 

(b) It shall be the duty of the Administrator to conduct the general administration of the Plan in accordance with the provisions of the Plan.
The Administrator shall have the power, subject to, and within the limitations of, the express provisions of the Plan: 
 (i)
To establish Offering Periods; 
 (ii) To determine when and how Options shall be granted and the provisions and terms of
each Offering Period (which need not be identical); 
 (iii) To select Designated Subsidiaries in accordance with
Section 7.2 hereof; and 

  
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 (iv) To construe and interpret the Plan, the terms of any Offering Period and the
terms of the Options and to adopt such rules for the administration, interpretation, and application of the Plan as are consistent therewith and to interpret, amend or revoke any such rules. The Administrator, in the exercise of this power, may
correct any defect, omission or inconsistency in the Plan, any Offering Period or any Option, in a manner and to the extent it shall deem necessary or expedient to make the Plan fully effect, subject to Section 423 of the Code and the Treasury
Regulations thereunder. 
 (c) The Administrator may adopt rules or procedures relating to the operation and administration of the Plan to
accommodate the specific requirements of local laws and procedures. Without limiting the generality of the foregoing, the Administrator is specifically authorized to adopt rules and procedures regarding handling of participation elections, payroll
deductions, payment of interest, conversion of local currency, payroll tax, withholding procedures and handling of stock certificates which vary with local requirements. In its absolute discretion, the Board may at any time and from time to time
exercise any and all rights and duties of the Administrator under the Plan. 
 (d) The Administrator may adopt sub-plans applicable to
particular Designated Subsidiaries or locations, which sub-plans may be designed to be outside the scope of Section 423 of the Code. The rules of such sub-plans may take precedence over other provisions of this Plan, with the exception of
Section 5.1 hereof, but unless otherwise superseded by the terms of such sub-plan, the provisions of this Plan shall govern the operation of such sub-plan. 

(e) All expenses and liabilities incurred by the Administrator in connection with the administration of the Plan shall be borne by the
Company. The Administrator may, with the approval of the Committee, employ attorneys, consultants, accountants, appraisers, brokers or other persons. The Administrator, the Company and its officers and directors shall be entitled to rely upon the
advice, opinions or valuations of any such persons. All actions taken and all interpretations and determinations made by the Administrator in good faith shall be final and binding upon all Participants, the Company and all other interested persons.
No member of the Board or Administrator shall be personally liable for any action, determination or interpretation made in good faith with respect to the Plan or the options, and all members of the Board or Administrator shall be fully protected by
the Company in respect to any such action, determination, or interpretation. 
 7.2 Designation of Subsidiary Corporations. The Board
or Committee shall designate from among the Subsidiaries, as determined from time to time, the Subsidiary or Subsidiaries that shall constitute Designated Subsidiaries. The Board or Committee may designate a Subsidiary, or terminate the designation
of a Subsidiary, without the approval of the stockholders of the Company. 
 7.3 Reports. Individual accounts shall be maintained for
each Participant in the Plan. Statements of Plan Accounts shall be given to Participants at least annually, which 

  
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statements shall set forth the amounts of payroll deductions, the Option Price, the number of shares purchased and the remaining cash balance, if any. 

7.4 No Right to Employment. Nothing in the Plan shall be construed to give any person (including any Participant) the right to remain
in the employ of the Company, a Parent or a Subsidiary or to affect the right of the Company, any Parent or any Subsidiary to terminate the employment of any person (including any Participant) at any time, with or without cause, which right is
expressly reserved. 
 7.5 Amendment and Termination of the Plan. 

(a) The Board may, in its sole discretion, amend, suspend or terminate the Plan at any time and from time to time; provided,
however, that without approval of the Company’s stockholders given within twelve (12) months before or after action by the Board, the Plan may not be amended to increase the maximum number of shares of Common Stock subject to the
Plan or change the designation or class of Eligible Employees; and provided, further that without approval of the Company’s stockholders, the Plan may not be amended in any manner that would cause the Plan to no longer be an
“employee stock purchase plan” within the meaning of Section 423(b) of the Code. 
 (b) In the event the Administrator
determines that the ongoing operation of the Plan may result in unfavorable financial accounting consequences, the Administrator may, to the extent permitted under Section 423 of the Code, in its discretion and, to the extent necessary or
desirable, modify or amend the Plan to reduce or eliminate such accounting consequence including, but not limited to: 
 (i)
altering the Option Price for any Offering Period including an Offering Period underway at the time of the change in Option Price; 

(ii) shortening any Offering Period so that the Offering Period ends on a new Exercise Date, including an Offering Period
underway at the time of the Administrator action; and 
 (iii) allocating shares of Common Stock. 

Such modifications or amendments shall not require stockholder approval or the consent of any Participant. 

(c) Upon termination of the Plan, the balance in each Participant’s Plan Account shall be refunded as soon as practicable after such
termination, without any interest thereon. 
 7.6 Use of Funds; No Interest Paid. All funds received by the Company by reason of
purchase of Common Stock under the Plan shall be included in the general funds of the Company free of any trust or other restriction and may be used for any corporate purpose. No interest shall be paid to any Participant or credited under the Plan.

  
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 7.7 Term; Approval by Stockholders. Subject to approval by the stockholders of the Company
in accordance with this Section 7.7, the Plan shall terminate on the tenth (10th) anniversary of the date of its initial approval by the stockholders of the Company, unless earlier
terminated in accordance with Sections 5.3 or 7.5 hereof. No Option may be granted during any period of suspension of the Plan or after termination of the Plan. The Plan shall be submitted for the approval of the Company’s stockholders within
twelve (12) months after the date of the Board’s initial adoption of the Plan. Options may be granted prior to such stockholder approval; provided, however, that such Options shall not be exercisable prior to the time when
the Plan is approved by the stockholders; provided, further that if such approval has not been obtained by the end of said twelve (12)-month period, all Options previously granted under the Plan shall thereupon terminate and be
canceled and become null and void without being exercised. 
 7.8 Effect Upon Other Plans. The adoption of the Plan shall not affect
any other compensation or incentive plans in effect for the Company, any Parent or any Subsidiary. Nothing in the Plan shall be construed to limit the right of the Company, any Parent or any Subsidiary (a) to establish any other forms of
incentives or compensation for Employees of the Company or any Parent or any Subsidiary, or (b) to grant or assume Options otherwise than under the Plan in connection with any proper corporate purpose, including, but not by way of limitation,
the grant or assumption of options in connection with the acquisition, by purchase, lease, merger, consolidation or otherwise, of the business, stock or assets of any corporation, firm or association. 

7.9 Conformity to Securities Laws. Notwithstanding any other provision of the Plan, the Plan and the participation in the Plan by any
individual who is then subject to Section 16 of the Exchange Act shall be subject to any additional limitations set forth in any applicable exemption rule under Section 16 of the Exchange Act (including any amendment to Rule 16b-3 of the Exchange Act) that are requirements for the application of such exemptive rule. To the extent permitted by applicable law, the Plan shall be deemed amended to the extent necessary to conform to such
applicable exemptive rule. 
 7.10 Notice of Disposition of Shares. Each Participant shall give the Company prompt notice of any
disposition or other transfer of any shares of Common Stock, acquired pursuant to the exercise of an Option, if such disposition or transfer is made (a) within two (2) years after the applicable Grant Date or (b) within one
(1) year after the transfer of such shares of Common Stock to such Participant upon exercise of such Option. The Company may direct that any certificates evidencing shares acquired pursuant to the Plan refer to such requirement. 

7.11 Tax Withholding. The Company or any Parent or any Subsidiary shall be entitled to require payment in cash or deduction from other
compensation payable to each Participant of any sums required by federal, state or local tax law to be withheld with respect to any purchase of shares of Common Stock under the Plan or any sale of such shares. 

7.12 Governing Law. The Plan and all rights and obligations thereunder shall be construed and enforced in accordance with the laws of
the State of Delaware. 
 7.13 Notices. All notices or other communications by a participant to the Company under or in connection
with the Plan shall be deemed to have been duly given when 

  
 13 

 
received in the form specified by the Company at the location, or by the person, designated by the Company for the receipt thereof. 

7.14 Conditions To Issuance of Shares. 

(a) Notwithstanding anything herein to the contrary, the Company shall not be required to issue or deliver any certificates or make any book
entries evidencing shares of Common Stock pursuant to the exercise of an Option by a Participant, unless and until the Board or the Committee has determined, with advice of counsel, that the issuance of such shares of Common Stock is in compliance
with all applicable laws, regulations of governmental authorities and, if applicable, the requirements of any securities exchange or automated quotation system on which the shares of Common Stock are listed or traded, and the shares of Common Stock
are covered by an effective registration statement or applicable exemption from registration. In addition to the terms and conditions provided herein, the Board or the Committee may require that a Participant make such reasonable covenants,
agreements, and representations as the Board or the Committee, in its discretion, deems advisable in order to comply with any such laws, regulations, or requirements. 

(b) All certificates for shares of Common Stock delivered pursuant to the Plan and all shares of Common Stock issued pursuant to book entry
procedures are subject to any stop-transfer orders and other restrictions as the Committee deems necessary or advisable to comply with federal, state, or foreign securities or other laws, rules and regulations and the rules of any securities
exchange or automated quotation system on which the shares of Common Stock are listed, quoted, or traded. The Committee may place legends on any certificate or book entry evidencing shares of Common Stock to reference restrictions applicable to the
shares of Common Stock. 
 (c) The Committee shall have the right to require any Participant to comply with any timing or other restrictions
with respect to the settlement, distribution or exercise of any Option, including a window-period limitation, as may be imposed in the sole discretion of the Committee. 

(d) Notwithstanding any other provision of the Plan, unless otherwise determined by the Committee or required by any applicable law, rule or
regulation, the Company may, in lieu of delivering to any Participant certificates evidencing shares of Common Stock issued in connection with any Option, record the issuance of shares of Common Stock in the books of the Company (or, as applicable,
its transfer agent or stock plan administrator). 
 7.15 Equal Rights and Privileges. Except with respect to sub-plans designed to be
outside the scope of Section 423 of the Code, all Eligible Employees of the Company (or of any Designated Subsidiary) shall have equal rights and privileges under this Plan to the extent required under Section 423 of the Code or the
regulations promulgated thereunder so that this Plan qualifies as an “employee stock purchase plan” within the meaning of Section 423 of the Code or the Treasury Regulations thereunder. Any provision of this Plan that is inconsistent
with Section 423 of the Code or the Treasury Regulations thereunder shall, without further act or amendment by the Company or the Board, be reformed to comply with the equal rights and privileges requirement of Section 423 of the Code or
the Treasury Regulations thereunder. 

  
 14EX-10.13

 Exhibit 10.13 

RELYPSA, INC. 

EMPLOYMENT AGREEMENT 

This Employment Agreement (the “Agreement”) is made and entered into by and between Jerry M. Buysse, Ph.D.
(“Executive”) and Relypsa, Inc. (the “Company”) (together referred to herein as the “Parties”), effective as of September 24, 2013 (the “Effective Date”). This Agreement
supersedes in its entirety that certain employment letter agreement dated as of October 18, 2007 (the “Prior Agreement”) and any agreement to which the Company is a party with respect to Executive’s employment with the
Company, except for the Proprietary Information and Inventions Agreement executed by Executive (the “Confidential Information Agreement”). 

R E C I T A L S 
 A. The
Company desires to assure itself of the continued services of Executive by engaging Executive to perform services under the terms hereof. 

B. Executive desires to provide continued services to the Company on the terms herein provided. 

C. The Parties desire to execute this Agreement to supersede in its entirety the Prior Agreement and reflect certain changes to
Executive’s employment with the Company effective as of the Effective Date. 
 D. Certain capitalized terms used in this Agreement are
defined in Section 11 below. 
 In consideration of the foregoing, and for other good and valuable consideration, including the
respective covenants and agreements set forth below, the receipt and sufficiency of which are hereby acknowledged, the Parties hereto agree as follows: 

1. Employment. 

(a) General. The Company shall employ Executive as a full-time employee of the Company effective as of the Effective Date for the
period and in the position set forth in this Section 1, and upon the other terms and conditions herein provided. 
 (b) Term of
Agreement. This Agreement shall become effective as of the Effective Date and terminate upon the date that all obligations of the parties hereto with respect to this Agreement have been satisfied. 

(c) Position and Duties. Executive shall continue to have the title of Chief Scientific Officer and Senior Vice President, Research,
and shall report to the Chief Executive Officer of the Company. Executive shall also serve in such other capacity or capacities as the Company may from time to time prescribe. As a Company employee, Executive will continue to be expected to comply
with Company policies. 

 (d) Location. Executive shall perform services for the Company at the Company’s
offices located in Redwood City, California or, with the Company’s consent, at any other place at which the Company maintains an office; provided, however, that the Company may from time to time require Executive to travel
temporarily to other locations in connection with the Company’s business. 
 (e) Exclusivity. During the term of this Agreement,

 (i) Executive shall devote Executive’s entire working time, attention and energies to the business of the Company and shall not
(A) accept any other employment or consultancy or (B) serve on the board of directors or similar body of any other entity, unless such position under this subsection (e)(i)(A) or (B) is approved by the Chief Executive Officer of the
Company (which such approval shall continue until such time as the Company provides notice to Executive that, in its reasonable judgment, such position is with a company that is competitive with the Company, interferes with Executive’s duties
to the Company or places Executive in a Competing Position with, or otherwise conflicts with, the interests of the Company, at which time the Company and Executive will discuss such conflict and the parties will use reasonable efforts to reach
agreement on its resolution); provided that Executive may engage in civic and not-for-profit activities, so long as such activities, in the aggregate, do not conflict with the interests of the Company or materially interfere with the performance of
Executive’s duties to the Company. The Company has already consented to Executive’s continuing employment or consultancy or service on each board of directors of which Executive is now a member as set forth on Exhibit A attached
hereto, which consent shall continue until such time as the Company provides notice to Executive that, in its reasonable judgment, such company competes with the Company, such service interferes with Executive’s duties to the Company or places
Executive in a Competing Position with, or otherwise conflicts with, the interests of the Company, and upon such notice the Company and Executive will discuss such conflict or Competing Position and the parties will use reasonable efforts to reach
agreement on its resolution. 
 (ii) Except with the prior written approval of the Chief Executive Officer (which the Chief Executive
Officer may grant or withhold in his or her discretion), Executive will not, while employed with the Company, or during any period during which Executive is receiving compensation or any other consideration for services from the Company, engage,
directly or indirectly, in any business activity (whether or not pursued for pecuniary advantage) that is or may be competitive with, or that might place Executive in a Competing Position to, that of the Company or any of its subsidiaries or
affiliates and/or any or its affiliates, subsidiaries, or joint ventures currently existing or which shall be established during Executive’s employment by the Company (collectively, “Affiliates”). 

(iii) During Executive’s employment by the Company, Executive agrees not to acquire, assume or participate in, directly or indirectly,
any financial position, investment or interest known by Executive to be adverse or antagonistic to the Company, its business or prospects, financial or otherwise or in any company, person or entity that is, directly or indirectly, competitive with
the business of the Company or any of its Affiliates; provided, however, Executive may accept equity compensation related to the positions or business activities engaged in which have been approved by the Company pursuant to subsections (e)(i) and
(ii) above. Ownership by Executive, as a passive investment, of less than one percent (1%)

  
 -2- 

 
of the outstanding shares of capital stock of any corporation with one or more classes of its capital stock listed on a national securities exchange or publicly traded on a national securities
exchange or in the over-the-counter market shall not constitute breach of this Section 1(e). 
 2. Compensation and Related
Matters. 
 (a) Base Salary. Executive’s annual base salary (“Base Salary”) will continue to be
$284,000, less payroll deductions and all required withholdings, payable in accordance with the Company’s normal payroll practices. The Board or a committee of the Board shall review Executive’s Base Salary periodically and any adjustments
to Executive’s Base Salary, if any, will be made solely at the discretion of the Board or a committee of the Board. 
 (b)
Bonus. Executive shall also continue to be eligible for an annual discretionary bonus of 25% of Executive’s then-Base Salary as determined by the Board or a committee of the Board in its sole discretion, based upon the Board’s or a
committee of the Board’s evaluation (in its sole discretion) of the achievement of specific individual and/or Company-wide performance goals. The applicable performance goals shall be established by the Board or a committee of the Board, in
their sole discretion, and set out in writing on or before the 90th day of each calendar year. The annual discretionary bonus, if any, shall be payable, less authorized deductions and required
withholdings, no later than March 15th following the end of the applicable calendar year. The amount of any annual discretionary bonus for which Executive is eligible shall be reviewed by the
Board or a committee of the Board from time to time. 
 (c) Equity Awards. 

(i) Executive shall be eligible to receive grants of equity awards in the Company’s sole discretion. 

(ii) In the event a Change in Control is consummated prior to the earlier of December 31, 2015 or approval of a new drug application
(NDA) for patiromer by the Food and Drug Administration (FDA), then, effective as of the first anniversary of the Change in Control, each outstanding equity award, including, without limitation, each stock option and restricted stock award, held by
Executive shall automatically become vested and, if applicable, exercisable and any forfeiture restrictions or rights of repurchase thereon shall immediately lapse, in each case, with respect to one hundred percent (100%) of the then-unvested
shares subject to such outstanding award, subject to Executive continuing to provide services to the Company or the surviving company through such date. For the avoidance of doubt, if a Change in Control is consummated on or after January 1,
2016, then this Section 2(c)(ii) is of no force or effect. 
 (d) Vacation; Benefits. Executive shall continue to be entitled to
paid time-off and such other benefits in accordance with Company policy for similarly situated senior management of the Company. 
 (e)
Business Expenses. The Company shall continue to reimburse Executive for all reasonable business expenses incurred in the conduct of Executive’s duties hereunder in accordance with the Company’s expense reimbursement policies. 

  
 -3- 

 (f) Additional Matters. Additional matters regarding Executive’s employment with the
Company shall be as set forth on an appendix attached hereto and signed by both Parties. 
 3. Termination. 

(a) At-Will Employment. The Company and Executive acknowledge that Executive’s employment is and shall continue to be
“at-will,” as defined under applicable law. This means that it is not for any specified period of time and can be terminated by Executive or by the Company at any time, with or without advance notice, and for any or no particular reason or
cause. It also means that Executive’s job duties, title and responsibility and reporting level, work schedule, compensation and benefits, as well as the Company’s personnel policies and procedures, may be changed with prospective effect,
with or without notice, at any time in the sole discretion of the Company. This “at-will” nature of Executive’s employment shall remain unchanged during Executive’s tenure as an employee and may not be changed, except in an
express writing signed by Executive and a duly authorized member of the Board. If Executive’s employment terminates for any reason, Executive shall not be entitled to any payments, benefits, damages, awards or compensation other than as
provided by this Agreement. 
 (b) Deemed Resignation. Upon termination of Executive’s employment for any reason, Executive
shall be deemed to have resigned from all offices and directorships, if any, then held with the Company or any of its affiliates, and, at the Company’s request, Executive shall execute such documents as are necessary or desirable to effectuate
such resignations. 
 4. Obligations upon Termination of Employment. 

(a) Executive’s Obligations. 

(i) Confidentiality. Without limiting the Confidential Information Agreement, except (A) as Executive reasonably and in good
faith determines to be required in the faithful performance of Executive’s duties hereunder, (B) as required by applicable law or (C) in accordance with Section 4(a)(iii) below, while Executive is employed by the Company, and
thereafter, Executive shall not directly or indirectly disclose or make available to any person, firm, corporation, association or other entity for any reason or purpose whatsoever, any Confidential Information (as defined below). Upon termination
of Executive’s employment with the Company, all Confidential Information in Executive’s possession that is in written or other tangible form (together with all copies or duplicates thereof, including computer files) shall be returned to
the Company and shall not be retained by Executive or furnished to any third party, in any form except as provided herein; provided, however, that Executive shall not be obligated to treat as confidential, or return to the Company copies of
any Confidential Information that (i) was publicly known at the time of disclosure to Executive, (ii) becomes publicly known or available thereafter other than by any means in violation of this Agreement or any other duty owed to the
Company by any person or entity, or (iii) is lawfully disclosed to Executive by a third party. For purposes of this Agreement, the term “Confidential Information” shall mean information disclosed to Executive or known by
Executive as a consequence of or through his or her relationship with the Company, about the customers, employees, business methods, public relations methods, organization, procedures or finances, including, without limitation, information of or
relating to customer lists, of the Company and its affiliates. In addition, Executive shall continue to be subject to the Confidential Information Agreement. 

  
 -4- 

 (ii) Non-Solicitation. In addition to each Executive’s obligations under the
Confidential Information Agreement, Executive shall not for a period of one (1) year following Executive’s termination of employment for any reason, either on Executive’s own account or jointly with or as a manager, agent, officer,
employee, consultant, partner, joint venturer, owner or stockholder or otherwise on behalf of any other person, firm or corporation, directly or indirectly solicit or attempt to solicit away from the Company any of its officers or employees or offer
employment to any person who is an officer or employee of the Company; provided, however, that a general advertisement to which an employee of the Company responds shall in no event be deemed to result in a breach of this Section 4(a).
Executive also agrees not to harass or disparage the Company or its employees, clients, directors or agents or divert or attempt to divert any actual or potential business of the Company. 

(iii) Response to Legal Process. Executive may respond to a lawful and valid subpoena or other legal process but shall give the
Company the earliest possible notice thereof, and shall, as much in advance of the return date as possible, make available to the Company and its counsel the documents and other information sought, and shall assist such counsel in resisting or
otherwise responding to such process. 
 (iv) Survival of Provisions. The provisions of this Section 4(a) shall survive the
termination or expiration of the applicable Executive’s employment with the Company and shall be fully enforceable thereafter. If it is determined by a court of competent jurisdiction in any state that any restriction in this Section 4(a)
is excessive in duration or scope or is unreasonable or unenforceable under the laws of that state, it is the intention of the parties that such restriction may be modified or amended by the court to render it enforceable to the maximum extent
permitted by the law of that state. 
 (b) Payments of Accrued Obligations upon Termination of Employment. Upon a termination of
Executive’s employment for any reason, Executive (or Executive’s estate or legal representative, as applicable) shall be entitled to receive, within ten (10) days after the date Executive terminates employment with the Company (or
such earlier date as may be required by applicable law): (i) any portion of Executive’s annual base salary earned through Executive’s termination date not theretofore paid, (ii) any expenses owed to Executive under
Section 2(e) above, (iii) any accrued but unused vacation pay owed to Executive pursuant to Section 2(d) above, and (iv) any amount arising from Executive’s participation in, or benefits under, any employee benefit plans,
programs or arrangements under Section 2(d) above, which amounts shall be payable in accordance with the terms and conditions of such employee benefit plans, programs or arrangements 

  
 -5- 

 (c) Severance Payments upon a Covered Termination Other Than During a Change in Control
Period. If Executive experiences a Covered Termination at any time other than during a Change in Control Period, and if Executive executes and fails to revoke during any applicable revocation period a general release of all claims against the
Company and its affiliates in a form acceptable to the Company (a “Release of Claims”) within sixty (60) days, or such shorter period of time specified by the Company, following such Covered Termination, then in addition to any
accrued obligations payable under Section 4(b) above, the Company shall provide Executive with the following: 
 (i) Severance.
Executive shall be entitled to receive an amount equal to nine (9) months of Executive’s then-existing base salary in effect as of Executive’s termination date, less applicable withholdings, and payable in a lump sum on the first
regular payroll date following the date of Executive’s Release of Claims becomes effective and irrevocable. 
 (ii) Continued
Healthcare. The Company shall notify Executive of any right to continue group health plan coverage sponsored by the Company or an affiliate of the Company immediately prior to Executive’s date of termination pursuant to the provisions of
the Consolidated Omnibus Budget Reconciliation Act of 1985, as amended (“COBRA”). If Executive elects to receive such continued healthcare coverage, the Company shall directly pay, or reimburse Executive for, the premium for
Executive and Executive’s covered dependents, less the amount of Executive’s monthly premium contributions for such coverage prior to termination, for the period commencing on the first day of the first full calendar month following the
date the Release of Claims becomes effective and irrevocable through the earlier of (i) the last day of the ninth (9th) full calendar month following the date the Release of Claims
becomes effective and irrevocable and (ii) the date Executive and Executive’s covered dependents, if any, become eligible for healthcare coverage under another employer’s plan(s). Executive shall notify the Company immediately if
Executive becomes covered by a group health plan of a subsequent employer. After the Company ceases to pay premiums pursuant to this Section 4(c)(ii), Executive may, if eligible, elect to continue healthcare coverage at Executive’s expense
in accordance the provisions of COBRA. 
 (d) Severance Payments upon a Covered Termination During a Change in Control Period. If
Executive experiences a Covered Termination during a Change in Control Period, and if Executive executes and fails to revoke during any applicable revocation period a Release of Claims within sixty (60) days, or such shorter period of time
specified by the Company, following such Covered Termination, then in addition to any accrued obligations payable under Section 4(b) above, the Company shall provide Executive with the following: 

(i) Severance. Executive shall be entitled to receive an amount equal to (i) twelve (12) months of Executive’s
then-existing annual base salary in effect as of Executive’s termination date plus (ii) Executive’s target annual bonus award, pro-rated based on the total number of days elapsed in the calendar year as of the termination date, but
only if, as of the date of Executive’s termination of employment, the Company and Executive were “on target” to achieve all applicable performance goals for such annual bonus as determined by the Board or a committee of the Board in
their sole discretion. Such amount will be subject to applicable withholdings and payable in a single lump sum cash payment on the first regular payroll date following the date the Release of Claims becomes effective and irrevocable. 

(ii) Equity Awards. Each outstanding equity award, including, without limitation, each stock option and restricted stock award, held
by Executive shall automatically become vested and, if applicable, exercisable and any forfeiture restrictions or rights of repurchase thereon shall immediately lapse, in each case, with respect to one hundred percent (100%) of the
then-unvested shares subject to such outstanding award effective as of immediately prior to such termination date. 

  
 -6- 

 (iii) Continued Healthcare. The Company shall notify Executive of any right to continue
group health plan coverage sponsored by the Company or an affiliate of the Company immediately prior to Executive’s date of termination pursuant to the provisions of COBRA. If Executive elects to receive such continued healthcare coverage, the
Company shall directly pay, or reimburse Executive for, the premium for Executive and Executive’s covered dependents, less the amount of Executive’s monthly premium contributions for such coverage prior to termination, for the period
commencing on the first day of the first full calendar month following the date the Release of Claims becomes effective and irrevocable through the earlier of (i) the last day of the twelfth
(12th) full calendar month anniversary following the date Release of Claims becomes effective and irrevocable and (ii) the date Executive and Executive’s covered dependents, if any,
become eligible for healthcare coverage under another employer’s plan(s). Executive shall notify the Company immediately if Executive becomes covered by a group health plan of a subsequent employer. After the Company ceases to pay premiums
pursuant to this Section 4(d)(iii), Executive may, if eligible, elect to continue healthcare coverage at Executive’s expense in accordance the provisions of COBRA. 

(e) No Other Severance. The provisions of this Section 4 shall supersede in their entirety any severance payment or other
arrangement provided by the Company, including, without limitation, the Prior Agreement and any severance plan of the Company. 
 (f) No
Requirement to Mitigate; Survival. Executive shall not be required to mitigate the amount of any payment provided for under this Agreement by seeking other employment or in any other manner. Notwithstanding anything to the contrary in this
Agreement, the termination of Executive’s employment shall not impair the rights or obligations of any party. 
 (g) Certain
Reductions. The Company shall reduce Executive’s severance benefits under this Agreement, in whole or in part, by any other severance benefits, pay in lieu of notice, or other similar benefits payable to Executive by the Company in
connection with Executive’s termination, including but not limited to payments or benefits pursuant to (i) any applicable legal requirement, including, without limitation, the Worker Adjustment and Retraining Notification Act, or
(ii) any Company policy or practice providing for Executive to remain on the payroll without being in active service for a limited period of time after being given notice of the termination of Executive’s employment. The benefits provided
under this Agreement are intended to satisfy, to the greatest extent possible, any and all statutory obligations that may arise out of Executive’s termination of employment. Such reductions shall be applied on a retroactive basis, with
severance benefits previously paid being recharacterized as payments pursuant to the Company’s statutory obligation. 
 5.
Limitation on Payments. Notwithstanding anything in this Agreement to the contrary, if any payment or distribution Executive would receive pursuant to this Agreement or otherwise (“Payment”) would (a) constitute a
“parachute payment” within the meaning of Section 280G of the Internal Revenue Code of 1986, as amended (the “Code”), and (b) but for this sentence, be subject to the excise tax imposed by Section 4999 of
the Code (the “Excise  

  
 -7- 

 
Tax”), then the Company shall cause to be determined, before any amounts of the Payment are paid to Executive, which of the following alternative forms of payment would maximize
Executive’s after-tax proceeds: (i) payment in full of the entire amount of the Payment (a “Full Payment”), or (ii) payment of only a part of the Payment so that Executive receives that largest Payment possible
without being subject to the Excise Tax (a “Reduced Payment”), whichever of the foregoing amounts, taking into account the applicable federal, state and local income taxes and the Excise Tax (all computed at the highest marginal
rate, net of the maximum reduction in federal income taxes which could be obtained from a deduction of such state and local taxes), results in Executive’s receipt, on an after-tax basis, of the greater amount of the Payment, notwithstanding
that all or some portion the Payment may be subject to the Excise Tax. 
 (a) If a Reduced Payment is made pursuant to this Section 5,
(i) the Payment shall be paid only to the extent permitted under the Reduced Payment alternative, and Executive shall have no rights to any additional payments and/or benefits constituting the Payment, and (ii) reduction in payments and/or
benefits will occur in the following order: (1) reduction of cash payments; (2) cancellation of accelerated vesting of equity awards other than stock options; (3) cancellation of accelerated vesting of stock options; and
(4) reduction of other benefits payable to Executive. In the event that acceleration of compensation from Executive’s equity awards is to be reduced, such acceleration of vesting shall be canceled in the reverse order of the date of grant.

 (b) The independent registered public accounting firm engaged by the Company for general audit purposes as of the day prior to the
effective date of the Change in Control shall make all determinations required to be made under this Section 5. If the independent registered public accounting firm so engaged by the Company is serving as accountant or auditor for the
individual, group or entity effecting the Change in Control, the Company shall appoint a nationally recognized independent registered public accounting firm to make the determinations required hereunder. The Company shall bear all expenses with
respect to the determinations by such independent registered public accounting firm required to be made hereunder. 
 (c) The independent
registered public accounting firm engaged to make the determinations hereunder shall provide its calculations, together with detailed supporting documentation, to the Company and Executive within 15 calendar days after the date on which
Executive’s right to a Payment is triggered (if requested at that time by the Company or Executive) or such other time as requested by the Company or Executive. If the independent registered public accounting firm determines that no Excise Tax
is payable with respect to a Payment, either before or after the application of the Reduced Amount, it shall furnish the Company and Executive with an opinion reasonably acceptable to Executive that no Excise Tax will be imposed with respect to such
Payment. Any good faith determinations of the accounting firm made hereunder shall be final, binding and conclusive upon the Company and Executive. 

6. Successors. 

(a) Company’s Successors. Any successor to the Company (whether direct or indirect and whether by purchase, merger, consolidation,
liquidation or otherwise) to all or substantially all of the Company’s business and/or assets shall assume the obligations under this 

  
 -8- 

 
Agreement and agree expressly to perform the obligations under this Agreement in the same manner and to the same extent as the Company would be required to perform such obligations in the absence
of a succession. For all purposes under this Agreement, the term “Company” shall include any successor to the Company’s business and/or assets which executes and delivers the assumption agreement described in this Section 6(a) or
which becomes bound by the terms of this Agreement by operation of law. 
 (b) Executive’s Successors. The terms of this
Agreement and all rights of Executive hereunder shall inure to the benefit of, and be enforceable by, Executive’s personal or legal representatives, executors, administrators, successors, heirs, distributees, devisees and legatees. 

7. Notices. Notices and all other communications contemplated by this Agreement shall be in writing and shall be deemed
to have been duly given when personally delivered or one day following mailing via Federal Express or similar overnight courier service. In the case of Executive, mailed notices shall be addressed to Executive at Executive’s home address that
the Company has on file for Executive. In the case of the Company, mailed notices shall be addressed to its corporate headquarters, and all notices shall be directed to the attention of the General Counsel of the Company. 

8. Dispute Resolution. To ensure the timely and economical resolution of disputes that arise in connection with this
Agreement, Executive and the Company agree that any and all disputes, claims, or causes of action arising from or relating to the enforcement, breach, performance or interpretation of this Agreement, Executive’s employment, or the termination
of Executive’s employment, shall be resolved to the fullest extent permitted by law by final, binding and confidential arbitration, by a single arbitrator, in San Mateo County, California, conducted by Judicial Arbitration and Mediation
Services, Inc. (“JAMS”) under the applicable JAMS employment rules. By agreeing to this arbitration procedure, both Executive and the Company waive the right to resolve any such dispute through a trial by jury or judge or
administrative proceeding. The arbitrator shall: (i) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; and (ii) issue a written
arbitration decision, to include the arbitrator’s essential findings and conclusions and a statement of the award. The arbitrator shall be authorized to award any or all remedies that Executive or the Company would be entitled to seek in a
court of law. The Company shall pay all JAMS’ arbitration fees in excess of the amount of court fees that would be required if the dispute were decided in a court of law. Nothing in this Agreement is intended to prevent either Executive or the
Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Notwithstanding the foregoing, Executive and the Company each have the right to resolve any issue or dispute over
intellectual property rights by Court action instead of arbitration. 
 9. Miscellaneous Provisions. 

(a) Withholdings and Offsets. The Company shall be entitled to withhold from any amounts payable under this Agreement any federal,
state, local or foreign withholding or other taxes or charges which the Company is required to withhold. The Company shall be entitled to rely on an opinion of counsel if any questions as to the amount or requirement of

  
 -9- 

 
withholding shall arise. If Executive is indebted to the Company at his or her termination date, the Company reserves the right to offset any severance payments under this Agreement by the amount
of such indebtedness. 
 (b) Waiver. No provision of this Agreement shall be modified, waived or discharged unless the modification,
waiver or discharge is agreed to in writing and signed by Executive and by an authorized officer of the Company (other than Executive). No waiver by either party of any breach of, or of compliance with, any condition or provision of this Agreement
by the other party shall be considered a waiver of any other condition or provision or of the same condition or provision at another time. 

(c) Whole Agreement. This Agreement and the Confidential Information Agreement represent the entire understanding of the parties hereto
with respect to the subject matter hereof and supersede all prior arrangements and understandings regarding same, including, without limitation, any severance plan of the Company’s, the Prior Agreement, and any accelerated vesting provisions of
Executive’s equity award agreements. Executive agrees and acknowledges that this Agreement supersedes and replaces in its entirety the Prior Agreement. The Company’s Executive Severance Benefit Plan, as amended, shall be of no further
force and effect and has been terminated by the Board. 
 (d) Amendment. This Agreement cannot be amended or modified except by a
written agreement signed by Executive and the Chief Executive Officer of the Company. 
 (e) Choice of Law. The validity,
interpretation, construction and performance of this Agreement shall be governed by the laws of the State of California. 
 (f)
Severability. The finding by a court of competent jurisdiction of the unenforceability, invalidity or illegality of any provision of this Agreement shall not render any other provision of this Agreement unenforceable, invalid or illegal. Such
court shall have the authority to modify or replace the invalid or unenforceable term or provision with a valid and enforceable term or provision which most accurately represents the intention of the parties hereto with respect to the invalid or
unenforceable term or provision. 
 (g) Interpretation; Construction. The headings set forth in this Agreement are for convenience of
reference only and shall not be used in interpreting this Agreement. This Agreement has been drafted by legal counsel representing the Company, but Executive has been encouraged to consult with, and has consulted with, Executive’s own
independent counsel and tax advisors with respect to the terms of this Agreement. The parties hereto acknowledge that each party hereto and its counsel has reviewed and revised, or had an opportunity to review and revise, this Agreement, and any
rule of construction to the effect that any ambiguities are to be resolved against the drafting party shall not be employed in the interpretation of this Agreement. 

(h) Representations; Warranties. Executive represents and warrants that Executive is not restricted or prohibited, contractually or
otherwise, from entering into and performing each of the terms and covenants contained in this Agreement, and that Executive’s execution and performance of this Agreement will not violate or breach any other agreements between Executive and any
other person or entity and that Executive has not engaged in any act or omission that could be reasonably expected to result in or lead to an event constituting “Cause” for purposes of this Agreement. 

  
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 (i) Counterparts. This Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which together will constitute one and the same instrument. 
 10. Section 409A.
The intent of the parties is that the payments and benefits under this Agreement comply with or be exempt from Section 409A of the Code and the Department of Treasury regulations and other interpretive guidance issued thereunder, including
without limitation any such regulations or other guidance that may be issued after the Effective Date, (“Section 409A”) and, accordingly, to the maximum extent permitted, this Agreement shall be interpreted to be in compliance
therewith. If the Company determines that any provision of this Agreement would cause Executive to incur any additional tax or interest under Section 409A (with specificity as to the reason therefor), the Company and Executive shall take
commercially reasonable efforts to reform such provision to try to comply with or be exempt from Section 409A through good faith modifications to the minimum extent reasonably appropriate to conform with Section 409A, provided that
any such modifications shall not increase the cost or liability to the Company. To the extent that any provision hereof is modified in order to comply with or be exempt from Section 409A, such modification shall be made in good faith and shall,
to the maximum extent reasonably possible, maintain the original intent and economic benefit to Executive and the Company of the applicable provision without violating the provisions of Section 409A. 

(a) Separation from Service. Notwithstanding any provision to the contrary in this Agreement, no amount deemed deferred compensation
subject to Section 409A of the Code shall be payable pursuant to Section 4 unless Executive’s termination of employment constitutes a “separation from service” with the Company within the meaning of Section 409A
(“Separation from Service”) and, except as provided under Section 10(b) of this Agreement, any such amount shall not be paid, or in the case of installments, commence payment, until the sixtieth (60th) day following Executive’s Separation from Service. Any installment payments that would have been made to Executive during the sixty (60) day period immediately following
Executive’s Separation from Service but for the preceding sentence shall be paid to Executive on the sixtieth (60th) day following Executive’s Separation from Service and the
remaining payments shall be made as provided in this Agreement. 
 (b) Specified Employee. Notwithstanding any provision to the
contrary in this Agreement, if Executive is deemed at the time of his or her separation from service to be a “specified employee” for purposes of Section 409A(a)(2)(B)(i) of the Code, to the extent delayed commencement of any portion
of the benefits to which Executive is entitled under this Agreement is required in order to avoid a prohibited distribution under Section 409A(a)(2)(B)(i) of the Code, such portion of Executive’s benefits shall not be provided to Executive
prior to the earlier of (a) the expiration of the six (6)-month period measured from the date of Executive’s Separation from Service or (b) the date of Executive’s death. Upon the first day of the seventh month following the date
of the Executive’s separation from service, all payments deferred pursuant to this Section 10(b) shall be paid in a lump sum to Executive, and any remaining payments due under this Agreement shall be paid as otherwise provided herein. 

  
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 (c) Expense Reimbursements. To the extent that any reimbursements payable pursuant to this
Agreement are subject to the provisions of Section 409A, any such reimbursements payable to Executive pursuant to this Agreement shall be paid to Executive no later than December 31 of the year following the year in which the expense was
incurred, the amount of expenses reimbursed in one year shall not affect the amount eligible for reimbursement in any subsequent year, and Executive’s right to reimbursement under this Agreement will not be subject to liquidation or exchange
for another benefit. 
 (d) Installments. For purposes of Section 409A (including, without limitation, for purposes of Treasury
Regulation Section 1.409A-2(b)(2)(iii)), Executive’s right to receive any installment payments under this Agreement shall be treated as a right to receive a series of separate payments and, accordingly, each such installment payment shall
at all times be considered a separate and distinct payment. 
 11. Definition of Terms. The following terms referred to
in this Agreement shall have the following meanings: 
 (a) Cause. “Cause” means the occurrence of any of the following
events, as determined by the Board or a committee designated by the Board, in its sole discretion: (i) Executive’s commission of any felony or any crime involving fraud, dishonesty, or moral turpitude under the laws of the United States or
any state thereof; (ii) Executive’s attempted commission of, or participation in, a fraud or act of dishonesty against the Company; (iii) Executive’s intentional, material violation of any contract or agreement between Executive
and the Company or of any statutory duty owed to the Company; (iv) Executive’s unauthorized use or disclosure of the Company’s confidential information or trade secrets; or (v) Executive’s gross misconduct. The determination
whether a termination is for “Cause” under the foregoing definition shall be made by the Company in its sole discretion. 
 (b)
Change in Control. “Change in Control” means the occurrence, in a single transaction or in a series of related transactions, of any one or more of the following events (excluding in any case transactions in which the Company or its
successors issues securities to investors primarily for capital raising purposes): (i) the acquisition by a third party of securities of the Company representing more than fifty percent (50%) of the combined voting power of the
Company’s then-outstanding securities other than by virtue of a merger, consolidation or similar transaction, (ii) a merger, consolidation or similar transaction following which the stockholders of the Company immediately prior thereto do
not own at least fifty percent (50%) of the combined outstanding voting power of the surviving entity (or that entity’s parent) in such merger, consolidation or similar transaction; (iii) the dissolution or liquidation of the Company;
or (iv) the sale, lease, exclusive license or other disposition of all or substantially all of the assets of the Company. Notwithstanding the foregoing, a “Change in Control” must also constitute a “change in control event”
as defined in Treasury Regulation §1.409A-3(i)(5). 
 (c) Change in Control Period. “Change in Control Period” means
the twelve (12) month period of time commencing upon the effective date of a Change in Control. 
 (d) Competing Position.
“Competing Position” shall mean engaging, directly or indirectly, in any manner or capacity, as adviser, principal, agent, affiliate, promoter, partner, 

  
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officer, director, employee, stockholder, owner, co-owner, consultant, or member of any association or otherwise, in any phase of the business of developing, manufacturing and marketing of
products or services which are in the same field of use or which otherwise compete with the Company and/or any of its Affiliates. 
 (e)
Covered Termination. “Covered Termination” shall mean the termination of Executive’s employment by the Company other than for Cause or by Executive for Good Reason. 

(f) Good Reason. “Good Reason” means Executive’s resignation from all positions he or she then holds with the Company if
(i) (A) there is a material diminution in Executive’s duties and responsibilities with the Company; provided, however, that a change in title or reporting relationship will not constitute Good Reason; (B) there is a
material reduction of Executive’s base salary; provided, however, that a material reduction in Executive’s base salary pursuant to a salary reduction program affecting all or substantially all of the employees of the Company
and that does not adversely affect Executive to a greater extent than other similarly situated employees shall not constitute Good Reason; or (C) Executive is required to relocate Executive’s primary work location to a facility or location
that would increase Executive’s one-way commute distance by more than twenty-five (25) miles from Executive’s primary work location as of immediately prior to such change, (ii) Executive provides written notice outlining such
conditions, acts or omissions to the Company within thirty (30) days immediately following such material change or reduction, (iii) such material change or reduction is not remedied by the Company within thirty (30) days following the
Company’s receipt of such written notice and (iv) Executive’s resignation is effective not later than thirty (30) days after the expiration of such thirty (30) day cure period. 

(Signature page follows) 

  
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 IN WITNESS WHEREOF, each of the parties has executed this Agreement, in the case of the Company
by its duly authorized officer, as of the day and year set forth below. 
  

			
	RELYPSA, INC.
		
	By:	 	 /s/ John A. Orwin

		
	Title:	 	President and Chief Executive Officer
	
	Date: October 31, 2013
	
	EXECUTIVE
	
	 /s/ Jerry M. Buysee, Ph.D.

	Name:	 	Jerry M. Buysse, Ph.D.
	
	Date: October 31, 2013

 Signature Page to Employment Agreement 

 EXHIBIT A 

Permitted Service Relationships Pursuant to Section 1(e) of the Agreement 

Consultant services agreement with Sibling Captial, LLC, dated and signed 23 May, 2013

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