Document:

Prothena Corporation plc 2012 Long Term Incentive Plan

 Exhibit 10.4 
 PROTHENA CORPORATION PLC 
 2012 LONG TERM INCENTIVE PLAN 

 TABLE OF CONTENTS 

Page 
  

							
			
	1.	  	Definitions	  	 	1	  
			
	2.	  	Administration	  	 	4	  
			
	3.	  	Shares Subject to the Plan	  	 	6	  
			
	4.	  	Specific Terms of Awards	  	 	7	  
			
	5.	  	Certain Provisions Applicable to Awards	  	 	11	  
			
	6.	  	Transferability of Awards	  	 	11	  
			
	7.	  	Change in Control Provisions	  	 	12	  
			
	8.	  	Qualified Performance-Based Compensation	  	 	12	  
			
	9.	  	General Provisions	  	 	13	  

  
 -i-

 PROTHENA CORPORATION PLC 

2012 LONG TERM INCENTIVE PLAN 
 The purposes of the 2012 Long Term Incentive Plan are to advance the interests of Prothena Corporation plc and its shareholders by providing a means to attract, retain, and motivate employees, consultants
and directors of Prothena Corporation plc, its subsidiaries and affiliates, to provide for competitive compensation opportunities, to encourage long term service, to recognize individual contributions and reward achievement of performance goals, and
to promote the creation of long term value for shareholders by aligning the interests of such persons with those of shareholders. 
  

	1.	Definitions. 

 For purposes of the Plan,
the following terms shall be defined as set forth below: 
 (a) “Act” means the Companies Act 1963 as amended
from time to time. References to any provision of the Act shall be deemed to include successor provisions thereto and regulations thereunder. 
 (b) “Affiliate” means any entity other than the Company and its Subsidiaries that is designated by the Board or the Committee as a participating employer under the Plan; provided,
however, that the Company directly or indirectly owns at least 20% of the combined voting power of all classes of stock of such entity or at least 20% of the ownership interests in such entity. 

(c) “Award” means any Option, SAR, Restricted Share, Restricted Share Unit, Performance Share, Performance Unit,
Dividend Equivalent, or Other Share-Based Award granted to an Eligible Person under the Plan. 
 (d) “Award
Agreement” means any written agreement, contract, or other instrument or document evidencing an Award. 
 (e)
“Beneficiary” means the person, persons, trust or trusts which have been designated by an Eligible Person in his or her most recent written beneficiary designation filed with the Company to receive the benefits specified under this
Plan upon the death of the Eligible Person, or, if there is no designated Beneficiary or surviving designated Beneficiary, then the person, persons, trust or trusts entitled by will or the laws of descent and distribution to receive such benefits.

 (f) “Board” means the Board of Directors of the Company. 

(g) “Change in Control” means: 
 (i) The consummation of a merger or consolidation of the Company with or into another entity or any other corporate reorganization (however effected, including by general offer or court-sanctioned
compromise, arrangement or scheme under the Act or otherwise) if more than 50% of the combined voting power of the continuing or surviving entity’s issued shares or securities outstanding immediately after such merger, consolidation or other
reorganization is owned by persons who were not shareholders of the Company immediately prior to such merger, consolidation or other reorganization; 
 (ii) The sale, transfer or other disposition of all or substantially all of the Company’s assets; 
 (iii) Individuals who as of the date the Board first consists of at least seven members constitute the Board (the “Incumbent Directors”) cease for any reason, including, without
limitation, as a result of a tender offer, proxy contest, merger or similar transaction, to constitute at least a majority of the Board; provided, however, that any individual who becomes a director of

  
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the Company subsequent to the date the Board first consists of at least seven members shall be considered an Incumbent Director if such person’s election or nomination for election was
approved by a vote of at least a majority of the Incumbent Directors; but, provided further that any such person whose initial assumption of office is in connection with an actual or threatened solicitation of proxies or consents by or on behalf of
a person other than the Board, including by reason of agreement intended to avoid or settle any such actual or threatened contest or solicitation, shall not be considered an Incumbent Director; or 

(iv) Any transaction as a result of which any person becomes the “beneficial owner” (as defined in Rule 13d-3
under the Exchange Act), directly or indirectly, of securities of the Company representing at least 50% of the total voting power represented by the Company’s then outstanding voting securities (e.g., issued shares). For purposes of this
subsection (v), the term “person” shall have the same meaning as when used in sections 13(d) and 14(d) of the Exchange Act but shall exclude (i) a trustee or other fiduciary holding securities under an employee benefit plan of the
Company or of any Subsidiary and (ii) a company owned directly or indirectly by the shareholders of the Company in substantially the same proportions as their ownership of the Shares of the Company. 

(v) Notwithstanding the foregoing, in the case of an Award that constitutes deferred compensation subject to section 409A
of the Code, the definition of “Change in Control” set forth above shall not apply, and the term “Change in Control” shall instead mean a “change in the ownership or effective control” of the Company or “in the
ownership of a substantial portion of the assets” of the Company within the meaning of section 409A(a)(2)(A)(v) of the Code and the regulations and guidance issued thereunder, but only to the extent this substitute definition is necessary in
order for the Award to comply with the requirements prescribed by section 409A of the Code. 
 (h) “Code” means
the Internal Revenue Code of 1986, as amended from time to time. References to any provision of the Code shall be deemed to include successor provisions thereto and regulations thereunder. 

(i) “Committee” means (i) with respect to Awards that are not intended to be “qualified performance-based
compensation” under section 162(m) of the Code and are not made to an individual subject to Section 16 of the Exchange Act, the Compensation Committee of the Board, or such other Board committee (which may include the entire Board) as may
be designated by the Board to administer the Plan, (ii) with respect to Awards that are intended to be “qualified performance-based compensation” under section 162(m) of the Code or made to an individual subject to Section 16 of
the Exchange Act, a committee that consists of two or more persons appointed by the Board, all of whom shall be “outside directors” as defined under section 162(m) of the Code and related Treasury Regulations and a “non-employee
directors” as defined by Rule 16b-3. 
 (j) “Company” means Prothena Corporation plc, a corporation
organized under the laws of Ireland, or any successor corporation. 
 (k) “Control” means the ownership
directly or indirectly of shares in a company carrying more than 50% of the total voting power represented by that company’s issued share capital. 
 (l) “Director” means a member of the Board who is not an employee of the Company, a Subsidiary or an Affiliate. 
 (m) “Dividend Equivalent” means a right, granted under Section 4(g), to receive cash, Shares, or other property equal in value to dividends paid with respect to a specified number of
Shares. Dividend Equivalents may be awarded on a free-standing basis or in connection with another Award, and may be paid currently or on a deferred basis. If interest is credited on accumulated dividend equivalents, the term “Dividend
Equivalent” shall include the accrued interest. 

  
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 (n) “Effective Date” has the meaning set forth in Section 9(m) below.

 (o) “Eligible Person” means (i) an employee or consultant of the Company, a Subsidiary or an Affiliate,
including any director who is an employee, or (ii) a Director. 
 (p) “Exchange Act” means the Securities
Exchange Act of 1934, as amended from time to time. References to any provision of the Exchange Act shall be deemed to include successor provisions thereto and regulations thereunder. 

(q) “Fair Market Value” means, with respect to Shares or other property, the fair market value of such Shares or other
property determined by such methods or procedures as shall be established from time to time by the Committee. If the Shares are listed on any established stock exchange or a national market system, unless otherwise determined by the Committee in
good faith, the Fair Market Value of Shares shall mean the closing price per Share during regular trading hours on the date in question (or, if the Shares were not traded on that day, the next preceding day that the Shares were traded). The
Committee may determine that, for an Award, the Fair Market Value of Shares shall mean the average of the closing price per Share during regular trading hours for a period, not to exceed 30 days, preceding the date in question on the principal
exchange or market system on which the Shares are traded, as such prices are officially quoted on such exchange. 
 (r)
“Full-Value Award” means any Award granted under the Plan other than an Option or a Share Appreciation Right. 

(s) “ISO” means any Option intended to be and designated as an incentive stock option within the meaning of section 422
of the Code. 
 (t) “NQSO” means any Option that is not an ISO. 

(u) “Option” means a right, granted under Section 4(b), to purchase Shares. 

(v) “Other Share-Based Award” means a right, granted under Section 4(h),that relates to or is valued by reference to
Shares. 
 (w) “Participant” means an Eligible Person who has been granted an Award under the Plan. 

(x) “Performance Period” has the meaning set forth in Section 4(f)(i) below 

(y) “Performance Share” means a performance share granted under Section 4(f). 

(z) “Performance Unit” means a performance unit granted under Section 4(f). 

(aa) “Plan” means this 2012 Long Term Incentive Plan. 

(bb) “Restricted Shares” means an Award of Shares under Section 4(d) that may be subject to certain restrictions
and to a risk of forfeiture. 
 (cc) “Restricted Share Unit” means a unit representing the Company’s
obligation to deliver or issue one Share for each such unit, granted under Section 4(e), or the cash equivalent, at the end of a specified deferral period. 
 (dd) “Rule 16b-3” means Rule 16b-3, as from time to time in effect and applicable to the Plan and Participants, promulgated by the Securities and Exchange Commission under section 16 of
the Exchange Act. 

  
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 (ee) “SAR” or “Share Appreciation Right” means the right,
granted under Section 4(c), to be paid an amount measured by the difference between the exercise price of the right and the Fair Market Value of Shares on the date of exercise of the right, with payment to be made in cash or Shares as specified
in the Award or determined by the Committee. 
 (ff) “Share” means one ordinary share, par value $ 0.01, in the
capital of the Company. 
 (gg) “Subsidiary” means any company which is, for the time being, a subsidiary of
the Company within the meaning of section 155 of the Act. For the avoidance of doubt, and provided it is not in conflict with the Act, this shall include any corporation (other than the Company) in an unbroken chain of corporations beginning with
the Company if each of the corporations (other than the last corporation in the unbroken chain) owns shares possessing 50% or more of the total combined voting power of all classes of stock in one of the other corporations in the chain. 

(hh) “Substitute Award” has the meaning set forth in Section 3(e) below 

(ii) “Termination of Service” means, unless otherwise defined in an applicable Award Agreement, that a Participant is no
longer employed by, providing consulting services to nor a director of the Company, its Subsidiaries and its Affiliates, as the case may be. A Participant employed by or providing service to a Subsidiary of the Company or one of its Affiliates shall
also be deemed to incur a Termination of Service if the Subsidiary of the Company or Affiliate ceases to be such a Subsidiary or an Affiliate, as the case may be, and the Participant does not immediately thereafter become an employee or director of,
or a consultant to, the Company, another Subsidiary of the Company or an Affiliate. Temporary absences from employment or service because of illness, vacation or leave of absence and transfers among the Company and its Subsidiaries and Affiliates
shall not be considered a Termination of Service. 
  

	2.	Administration. 

 (a)
Authority of the Committee. The Plan shall be administered by the Committee, and the Committee shall have full and final authority to take the following actions, in each case subject to and consistent with the provisions of the Plan:

 (i) to select Eligible Persons to whom Awards may be granted; 

(ii) to designate Affiliates; 
 (iii) to determine the type or types of Awards to be granted to each Eligible Person; 
 (iv) to determine the type and number of Awards to be granted, the number of Shares to which an Award may relate, the terms and conditions of any Award granted under the Plan (including, but not limited
to, any exercise price, grant price, or purchase price, any restriction or condition, any schedule for lapse of restrictions or conditions relating to transferability or forfeiture, exercisability, or settlement of an Award, and waiver or
accelerations thereof, and waivers of performance conditions relating to an Award, based in each case on such considerations as the Committee shall determine), and all other matters to be determined in connection with an Award; 

(v) to determine whether, to what extent, and under what circumstances an Award may be settled, or the exercise price of
an Award may be paid, in cash, Shares or other Awards, or an Award may be cancelled, forfeited, exchanged, or surrendered; 
 (vi) to determine whether, to what extent, and under what circumstances cash, Shares, other Awards, or other property payable with respect to an Award will be deferred either automatically, at the
election of the Committee, or at the election of the Eligible Person; 

  
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 (vii) to prescribe the form of each Award Agreement, which need not be
identical for each Eligible Person; 
 (viii) to adopt, amend, suspend, waive, and rescind such rules and
regulations and appoint such agents as the Committee may deem necessary or advisable to administer the Plan; 

(ix) to correct any defect or supply any omission or reconcile any inconsistency in the Plan and to construe and interpret
the Plan and any Award, rules and regulations, Award Agreement, or other instrument thereunder; 
 (x) to
accelerate the exercisability or vesting of all or any portion of any Award (provided that, except in the event of vesting due to a Change in Control or Termination of Service, no Award shall vest in full until at least the second anniversary of the
grant date of such Award) or to extend the period during which an Award is exercisable ; 
 (xi) to determine
whether uncertificated Shares may be used in satisfying Awards and otherwise in connection with the Plan; and 

(xii) to make all other decisions and determinations as may be required under the terms of the Plan or as the Committee
may deem necessary or advisable for the administration of the Plan. 
 (b) Manner of Exercise of Committee Authority. The
Committee shall have sole discretion in exercising its authority under the Plan. Any action of the Committee with respect to the Plan shall be final, conclusive, and binding on all persons, including the Company, Subsidiaries, Affiliates, Eligible
Persons, any person claiming any rights under the Plan from or through any Eligible Person, and shareholders. By accepting an Award under the Plan, each Eligible Person accepts the authority and discretion of the Committee as set forth in, and
exercised in accordance with, this Plan. The express grant of any specific power to the Committee, and the taking of any action by the Committee, shall not be construed as limiting any power or authority of the Committee. The Committee may delegate
to other members of the Board or officers or managers of the Company or any Subsidiary or Affiliate the authority, subject to such terms as the Committee shall determine, to perform administrative functions and, with respect to Awards granted to
persons not subject to section 16 of the Exchange Act, to perform such other functions as the Committee may determine, to the extent permitted under Rule 16b-3 (if applicable) and applicable law. 

(c) Limitation of Liability. Each member of the Committee shall be entitled to rely or act upon, in good faith, any report or
other information furnished to him or her by any officer or other employee of the Company or any Subsidiary or Affiliate, the Company’s independent public accountants, or other professional retained by the Company to assist in the
administration of the Plan. No member of the Committee, and no officer or employee of the Company acting on behalf of the Committee, shall be personally liable for any action, determination, or interpretation taken or made in good faith with respect
to the Plan, and all members of the Committee and any officer or employee of the Company acting on their behalf shall, to the extent permitted by law, be fully indemnified and protected by the Company with respect to any such action, determination,
or interpretation. 
 (d) No Option or SAR Repricing Without Shareholder Approval. Except in connection with a corporate
transaction involving the Company (including, without limitation, any stock dividend, stock split, extraordinary cash dividend, recapitalization, reorganization, merger, consolidation, split-up, spin-off, combination, or exchange of shares), the
terms of outstanding Awards may not be amended to reduce the exercise price of outstanding Options or the base amount of outstanding SARs or cancel outstanding Options or SARs in exchange for cash, other awards or Options or SARs with an exercise
price or base amount, as applicable, that is less than the exercise price or base amount, as applicable, of the original Options or SARs without shareholder approval. No amendment or adjustment under this Section 2(d) shall have the effect of
reducing the amount payable for a Share to less than the par value of a Share. 

  
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	3.	Shares Subject to the Plan. 

 (a) Subject to adjustment as provided in Section 3(c), the total number of Shares reserved for issuance in connection with Awards under the Plan is 2,650,000. No Award may be granted if the number of
Shares to which such Award relates, when added to the number of Shares previously issued under the Plan, exceeds the number of Shares reserved under the preceding sentence. Shares issued or transferred under the Plan may be authorized but unissued
Shares or reacquired Shares, including Shares purchased by the Company on the open market for purposes of the Plan. If and to the extent any Options or SARs are forfeited, cancelled, terminated, exchanged or surrendered without having been
exercised, or the Shares subject to Options are withheld or surrendered to satisfy the exercise price of any Options or the minimum tax withholding obligations of any Options or SARs under Section 9(c), the Shares subject to such Awards shall
again be available for all purposes of the Plan. If and to the extent any Full Value Awards are forfeited or terminated, or otherwise not paid in full, or the Shares subject thereto are withheld or surrendered for purposes of satisfying the minimum
tax withholding obligations under Section 9(c), the Shares subject to such Awards shall again be available for all purposes of the Plan. To the extent an Award is settled in cash, any Shares counted against the number of Shares reserved and
available under the Plan with respect to such Award shall, to the extent of any such forfeiture, settlement, termination, cancellation, exchange or surrender, again be available for all purposes of the Plan. Upon the exercise of any Award granted in
tandem with any other Awards, such related Awards shall be cancelled to the extent of the number of Shares as to which the Award is exercised. For the avoidance of doubt, if Shares are repurchased on the open market with proceeds of the exercise
price of Options, such Shares may not again be made available for issuance under the Plan. 
 (b) All Awards under the Plan,
other than Dividend Equivalents, shall be expressed in Shares of stock. The maximum aggregate number of Shares with respect to which all Awards, other than Dividend Equivalents, may be made under the Plan to any individual during any calendar year
shall be 750,000 Shares, subject to adjustment as described below. The same limit shall apply with respect to the maximum aggregate number of Shares with respect to which Options and SARs may be made under the Plan to any individual during any
calendar year. A Participant may not accrue Dividend Equivalents during any calendar year in excess of $750,000. The individual limits described in this subsection (b) shall apply without regard to whether the Awards are to be paid in Shares of
stock or in cash. All cash payments (other than Dividend Equivalents) shall equal the Fair Market Value of the Shares of stock to which the cash payment relates. Notwithstanding anything to the contrary herein, the foregoing limitations shall not
apply until the earliest of: (a) the first material modification of the Plan; (b) the issuance of all of the Shares reserved for issuance under the Plan; (c) the expiration of the Plan; (d) the end of the reliance period pursuant
to Section 162(m) of the Code and the rules and regulations promulgated thereunder; or (e) such other date required by Section 162(m) of the Code and the rules and regulations promulgated thereunder. To the extent required by
Section 162(m) of the Code, Shares subject to Awards which are cancelled shall continue to be counted against the limitations provided for herein. 
 (c) In the event that the Committee shall determine that any dividend in Shares, recapitalization, Share split, reverse split, reorganization, merger, consolidation, spin-off, combination, repurchase,
share exchange, extraordinary distribution, or other similar corporate transaction or event, affects the Shares such that an adjustment is appropriate in order to prevent dilution or enlargement of the rights of the Participants under the Plan, then
the Committee shall make such equitable changes or adjustments as it deems appropriate and, in such manner as it may deem equitable, (i) adjust any or all of (x) the number and kind of shares which may thereafter be issued under the Plan,
(y) the number and kind of shares, other securities or other consideration issued or issuable in respect of outstanding Awards, and (z) the exercise price, grant price, or purchase price relating to any Award or (ii) provide for a
distribution of cash or property in respect of any Award; provided, however, in each case that, with respect to ISOs, such adjustment shall be made in accordance with section 424(a) of the Code, unless the Committee determines otherwise; provided
further, however, that no adjustment shall be made pursuant to this Section 3 that causes any Award to be treated as deferred compensation pursuant to section 409A of the Code. In addition, the Committee is authorized to make adjustments in the
terms and conditions of, and the criteria and performance objectives, if any, included in, Awards in recognition of unusual or non-recurring events (including, without limitation, events described in the preceding sentence) affecting the Company or
any 

  
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Subsidiary or Affiliate or the financial statements of the Company or any Subsidiary or Affiliate, or in response to changes in applicable laws, regulations, or accounting principles. No
amendment or adjustment under this Section 3(c) shall have the effect of reducing the amount payable for a Share to less than the par value of a Share. In addition, in the event of a Change of Control, the provisions of Section 7 shall
apply. Any adjustments determined by the Committee shall be final, binding and conclusive. 
 (d) Any Shares distributed
pursuant to an Award may consist, in whole or in part, of authorized and unissued Shares or treasury Shares including Shares acquired by purchase in the open market or in private transactions. 

(e) In connection with the acquisition of any business by the Company or any of its Subsidiaries, any outstanding equity grants with
respect to stock of the acquired company may be assumed or replaced by Awards under the Plan upon such terms and conditions as the Committee determines in its sole discretion. Shares subject to any such outstanding grants that are assumed or
replaced by Awards under the Plan in connection with an acquisition (“Substitute Awards”) shall not reduce the aggregate share limit set forth in Section 3(a), consistent with applicable stock exchange requirements.
Notwithstanding any provision of the Plan to the contrary, Substitute Awards shall have such terms as the Committee deems appropriate, including without limitation exercise prices or base prices on different terms than those described herein,
provided that the terms of such Substitute Awards shall not have the effect of reducing the amount payable for a Share to less than the par value of a Share. In the event that the Company assumes a shareholder-approved equity plan of an acquired
company, available Shares under such assumed plan (after appropriate adjustments to reflect the transaction) may be issued pursuant to Awards under this Plan and shall not reduce the aggregate share limit set forth in Section 3(a), subject to
applicable stock exchange requirements. 
  

	4.	Specific Terms of Awards. 

(a) General. Awards may be granted on the terms and conditions set forth in this Section 4. In addition, the Committee may
impose on any Award or the exercise thereof, at the date of grant or thereafter (subject to Section 9(d)), such additional terms and conditions, not inconsistent with the provisions of the Plan, as the Committee shall determine, including terms
regarding forfeiture of Awards or continued exercisability of Awards in the event of Termination of Service by the Eligible Person. All Awards shall be made conditional upon the Participant’s acknowledgement, in writing or by acceptance of the
Award, that all decisions and determinations of the Committee shall be final and binding on the Participant, his or her beneficiaries and any other person having or claiming an interest under such Award. Awards under a particular Section of the Plan
need not be uniform as among the Participants. 
 (b) Options. The Committee is authorized to grant Options, which may be
NQSOs or ISOs, to Eligible Persons on the following terms and conditions: 
 (i) Exercise Price. The
exercise price per Share purchasable under an Option shall be determined by the Committee; provided, however, that the exercise price per Share shall not be less than the Fair Market Value per Share on the date of grant. 

(ii) Option Term. The term of each Option shall be determined by the Committee; provided, however, that such term
shall not be longer than ten years from the date of grant of the Option. 
 (iii) Time and Method of Exercise.
The Committee shall determine at the date of grant or thereafter the time or times at which an Option may be exercised in whole or in part (including, without limitation, upon achievement of performance criteria if deemed appropriate by the
Committee), the methods by which such exercise price may be paid or deemed to be paid (including, without limitation, broker-assisted exercise arrangements), the form of such payment (cash or Shares), and the methods by which Shares will be
delivered or deemed to be delivered to Eligible Persons. 

  
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 (iv) Early Exercise. The Committee may provide at the time of grant
or any time thereafter, in its sole discretion, that any Option shall be exercisable with respect to Shares that otherwise would not then be exercisable, provided that, in connection with such exercise, the Participant enters into a form of
Restricted Share agreement approved by the Committee with respect to the Shares received on exercise. 
 (v)
ISOs. The terms of any ISO granted under the Plan shall comply in all respects with the provisions of section 422 of the Code, including but not limited to the requirement that the ISO shall be granted within ten years from the earlier of the
date of adoption or shareholder approval of the Plan. ISOs may only be granted to employees of the Company or a Subsidiary. 

(c) SARs. The Committee is authorized to grant SARs to Eligible Persons on the following terms and conditions: 

(i) Right to Payment. A SAR shall confer on the Eligible Person to whom it is granted a right to receive with
respect to each Share subject thereto, upon exercise thereof, the excess of (1) the Fair Market Value of one Share on the date of exercise over (2) the exercise price per Share of the SAR, as determined by the Committee as of the date of
grant of the SAR (which shall not be less than the Fair Market Value per Share on the date of grant). 
 (ii)
Other Terms. The Committee shall determine, at the time of grant, the time or times at which a SAR may be exercised in whole or in part (which shall not be more than ten years after the date of grant of the SAR), the method of exercise,
method of settlement, form of consideration payable in settlement (whether paid in the form of cash, in Shares of stock or a combination of the two), method by which Shares will be delivered or deemed to be delivered to Eligible Persons, whether or
not a SAR shall be in tandem with any other Award, and any other terms and conditions of any SAR. Unless the Committee determines otherwise, a SAR (1) granted in tandem with an NQSO may be granted at the time of grant of the related NQSO or at
any time thereafter and (2) granted in tandem with an ISO may only be granted at the time of grant of the related ISO. 

(d) Restricted Shares. The Committee is authorized to grant Restricted Shares to Eligible Persons on the following terms and
conditions: 
 (i) Issuance and Restrictions. Restricted Shares shall be subject to such restrictions on
transferability and other restrictions, if any, as the Committee may impose at the date of grant or thereafter, which restrictions may lapse separately or in combination at such times, under such circumstances (including, without limitation, upon
achievement of performance criteria if deemed appropriate by the Committee), in such installments, or otherwise, as the Committee may determine. Except to the extent restricted under the Award Agreement relating to the Restricted Shares or set forth
in Section 4(d)(iv) below, an Eligible Person granted Restricted Shares shall have all of the rights of a shareholder including, without limitation, the right to vote Restricted Shares and the right to receive dividends thereon (subject to
clause (iv) below). 
 (ii) Forfeiture. Except as otherwise determined by the Committee, at the date
of grant or thereafter, upon Termination of Service during the applicable restriction period, Restricted Shares and any accrued but unpaid dividends or Dividend Equivalents that are at that time subject to restrictions shall be forfeited; provided,
however, that the Committee may provide, by rule or regulation or in any Award Agreement, or may determine in any individual case, that restrictions or forfeiture conditions relating to Restricted Shares will be waived in whole or in part in the
event of Termination of Service resulting from specified causes, and the Committee may in other cases waive in whole or in part the forfeiture of Restricted Shares. 

(iii) Certificates for Shares. Restricted Shares granted under the Plan may be evidenced in such manner as the
Committee shall determine. If certificates representing Restricted Shares are registered in the name of the Participant, such certificates shall bear an appropriate 

  
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legend referring to the terms, conditions, and restrictions applicable to such Restricted Shares, and, unless otherwise determined by the Committee, the Company shall retain physical possession
of the certificate and the Participant shall deliver a stock power to the Company, endorsed in blank, relating to the Restricted Shares. 
 (iv) Dividends. Dividends paid on Restricted Shares shall be either paid at the dividend payment date, or deferred for payment to such date as determined by the Committee, consistent with the
requirements of section 409A of the Code, in cash or in unrestricted Shares having a Fair Market Value equal to the amount of such dividends. Unless otherwise determined by the Committee, Shares distributed in connection with a Share split or
dividend in Shares, and cash or other property distributed as a dividend, shall be subject to restrictions and a risk of forfeiture to the same extent as the Restricted Shares with respect to which such Shares or other property has been distributed.
Payment of any dividends deferred pursuant to this subsection (iv) shall be made only upon an event permitted by section 409A of the Code. Dividends may accrue on unearned Performance Shares but shall not be payable unless and until the
applicable performance goals are met. 
 (v) Early Exercise Options. The Committee shall award Restricted
Shares to a Participant upon the Participant’s early exercise of an Option under Section 4(b)(iv) hereof. Unless otherwise determined by the Committee, the lapse of restrictions with respect to such Restricted Shares shall occur on the
same schedule as the exercisability of the Option for which the Restricted Shares were exercised. 
 (e) Restricted Share
Units. The Committee is authorized to grant Restricted Share Units to Eligible Persons, subject to the following terms and conditions: 
 (i) Award and Restrictions. Delivery of Shares or cash, as the case may be, will occur upon expiration of the deferral period specified for Restricted Share Units by the Committee (or, if permitted
by the Committee, as elected by the Eligible Person), but consistent with the requirements of section 409A of the Code. In addition, Restricted Share Units shall be subject to such restrictions as the Committee may impose, if any (including, without
limitation, the achievement of performance criteria if deemed appropriate by the Committee), at the date of grant or thereafter, which restrictions may lapse at the expiration of the deferral period or at earlier or later specified times, separately
or in combination, in installments or otherwise, as the Committee may determine. 
 (ii) Forfeiture.
Except as otherwise determined by the Committee at the date of grant or thereafter, upon Termination of Service during the applicable deferral period or portion thereof to which forfeiture conditions apply (as provided in the Award Agreement
evidencing the Restricted Share Units), or upon failure to satisfy any other conditions precedent to the delivery of Shares or cash to which such Restricted Share Units relate, all Restricted Share Units that are at that time subject to deferral or
restriction shall be forfeited; provided, however, that the Committee may provide, by rule or regulation or in any Award Agreement, or may determine in any individual case, that restrictions or forfeiture conditions relating to Restricted Share
Units will be waived in whole or in part in the event of Termination of Service resulting from specified causes, and the Committee may in other cases waive in whole or in part the forfeiture of Restricted Share Units. 

(iii) Dividend Equivalents. Unless otherwise determined by the Committee at the date of grant, Dividend Equivalents
on the specified number of Shares covered by a Restricted Share Unit shall be either (A) paid with respect to such Restricted Share Unit that is not a Performance Unit at the dividend payment date in cash or in unrestricted Shares having a Fair
Market Value equal to the amount of such dividends, or (B) deferred with respect to such Restricted Share Unit, consistent with the requirements of section 409A of the Code and the amount or value thereof paid in cash pursuant to the vesting
schedule of the Restricted Share Unit or automatically deemed reinvested in additional Restricted Share Units or other Awards, as the Committee shall determine or permit the Participant to elect. Payment of any Dividend

  
 9 

 
Equivalents deferred pursuant to this subsection (iii) shall be made only upon an event permitted by section 409A of the Code. Dividend Equivalents may accrue on unearned Performance Units
but shall not be payable unless and until the applicable performance goals are met. 
 (f) Performance Shares and Performance
Units. The Committee is authorized to grant Performance Shares or Performance Units or both to Eligible Persons on the following terms and conditions: 
 (i) Performance Period. The Committee shall determine a performance period (the “Performance Period”) of one or more years or other periods and shall determine the performance
objectives for grants of Performance Shares and Performance Units. Performance objectives may vary from Eligible Person to Eligible Person and shall be based upon the performance criteria as the Committee may deem appropriate. The performance
objectives may be determined by reference to the performance of the Company, or of a Subsidiary or Affiliate, or of a division or unit of any of the foregoing. Performance Periods may overlap and Eligible Persons may participate simultaneously with
respect to Performance Shares and Performance Units for which different Performance Periods are prescribed. 

(ii) Award Value. At the beginning of a Performance Period, the Committee shall determine for each Eligible Person
or group of Eligible Persons with respect to that Performance Period the range of number of Shares, if any, in the case of Performance Shares, and the range of dollar values, if any, in the case of Performance Units, which may be fixed or may vary
in accordance with such performance or other criteria specified by the Committee, which shall be paid to a Participant as an Award if the relevant measure of Company performance for the Performance Period is met. 

(iii) Significant Events. If during the course of a Performance Period there shall occur significant events as
determined by the Committee which the Committee expects to have a substantial effect on a performance objective during such period, the Committee may revise such objective. 

(iv) Forfeiture. Except as otherwise determined by the Committee, at the date of grant or thereafter, upon
Termination of Service during the applicable Performance Period, Performance Shares and Performance Units for which the Performance Period was prescribed shall be forfeited; provided, however, that the Committee may provide, by rule or regulation or
in any Award Agreement, or may determine in an individual case, that restrictions or forfeiture conditions relating to Performance Shares and Performance Units will be waived in whole or in part in the event of Termination of Service resulting from
specified causes, and the Committee may in other cases waive in whole or in part the forfeiture of Performance Shares and Performance Units. 
 (v) Payment. Each Performance Share or Performance Unit may be paid in whole Shares, or cash, or a combination of Shares and cash either as a lump sum payment or in installments, all as the
Committee shall determine, at the time of grant of the Performance Share or Performance Unit or otherwise, commencing as soon as practicable after the end of the relevant Performance Period. 

(g) Dividend Equivalents. The Committee is authorized to grant Dividend Equivalents to Eligible Persons. Dividend Equivalents
shall not be granted with respect to Options or SARs. The Committee may provide, at the date of grant or thereafter, that Dividend Equivalents shall be paid or distributed when accrued, when the underlying Award vests or shall be deemed to have been
reinvested in additional Shares, or other investment vehicles as the Committee may specify; provided, however, that Dividend Equivalents (other than freestanding Dividend Equivalents) shall be subject to all conditions and restrictions of any
underlying Full Value Awards to which they relate. Dividend Equivalents may accrue on unearned performance-based Full Value Awards but shall not be payable unless and until such performance goals are met. 

  
 10 

 (h) Other Share-Based Awards. The Committee is authorized, subject to limitations
under applicable law, to grant to Eligible Persons such other Awards that may be denominated or payable in, valued in whole or in part by reference to, or otherwise based on, or related to, Shares, as deemed by the Committee to be consistent with
the purposes of the Plan, including, without limitation, unrestricted shares awarded purely as a “bonus” and not subject to any restrictions or conditions, other rights convertible or exchangeable into Shares, purchase rights for Shares,
Awards with value and payment contingent upon performance of the Company or any other factors designated by the Committee, and Awards valued by reference to the performance of specified Subsidiaries or Affiliates. The Committee shall determine the
terms and conditions of such Awards at date of grant or thereafter. Shares delivered pursuant to an Award in the nature of a purchase right granted under this Section 4(h) shall be purchased for such consideration, paid for at such times, by
such methods, and in such forms, including, without limitation, cash, Shares, notes or other property, as the Committee shall determine. Cash awards, as an element of or supplement to any other Award under the Plan, shall also be authorized pursuant
to this Section 4(h). 
 (i) Payment of par value of Shares. The Committee may require that a condition of the
delivery of Shares under Section 4(b), 4(c), 4(d), 4(e) or 4(f) above is that the Participant pays the par value of Shares to the Company prior to delivery of the Shares, if required to do so under the Act. 

 

	5.	Certain Provisions Applicable to Awards. 

 (a) Stand-Alone, Additional, Tandem and Substitute Awards. Awards granted under the Plan may, in the discretion of the Committee, be granted to Eligible Persons either alone or in addition to, in
tandem with, or in exchange or substitution for, any other Award granted under the Plan or any award granted under any other plan or agreement of the Company, any Subsidiary or Affiliate, or any business entity to be acquired by the Company or a
Subsidiary or Affiliate, or any other right of an Eligible Person to receive payment from the Company or any Subsidiary or Affiliate. Awards may be granted in addition to or in tandem with such other Awards or awards, and may be granted either as of
the same time as, or a different time from, the grant of such other Awards or awards. Subject to the provisions of Section 2(d) hereof prohibiting Option and SAR repricing without shareholder approval, the per Share exercise price of any
Substitute Award shall be determined by the Committee, in its discretion. 
 (b) Term of Awards. The term of each Award
granted to an Eligible Person shall be for such period as may be determined by the Committee; provided, however, that in no event shall the term of any Option or SAR exceed a period of ten years from the date of its grant (or such shorter period as
may be applicable under section 422 of the Code). 
 (c) Form of Payment Under Awards. Subject to the terms of the Plan
and any applicable Award Agreement, payments to be made by the Company or a Subsidiary or Affiliate upon the grant, maturation, or exercise of an Award may be made in such forms as the Committee shall determine at the date of grant or thereafter,
including, without limitation, cash, Shares, notes or other property (if permissible under section 409A of the Code and the Act), and may be made in a single payment or transfer, in installments, or on a deferred basis, consistent with the
requirements of section 409A of the Code and the Act. The Committee may make rules relating to installment or deferred payments with respect to Awards, consistent with the requirements of section 409A of the Code, including the rate of interest, if
any, to be credited with respect to such payments. 
 (d) Noncompetition. The Committee may, by way of the Award
Agreements or otherwise, establish such other terms, conditions, restrictions and/or limitations, if any, of any Award, provided they are not inconsistent with the Plan and applicable law, including, without limitation, the requirement that the
Participant not engage in competition with, solicit customers or employees of, or disclose or use confidential information of the Company or its Subsidiaries and Affiliates. 

  
 11 

	6.	Transferability of Awards. 

(a) Restrictions on Transfer. Except as described in this Section 6, or unless otherwise set forth by the Committee in an
Award Agreement, Awards shall not be transferable by a Participant except by will or the laws of descent and distribution (except pursuant to a Beneficiary designation) and shall be exercisable during the lifetime of a Participant only by such
Participant or his guardian or legal representative. A Participant’s rights under the Plan may not be pledged, mortgaged, hypothecated, or otherwise encumbered, and shall not be subject to claims of the Participant’s creditors. 

(b) Transfer of NQSOs. Notwithstanding the foregoing, the Committee may provide in a Award Agreement that a Participant may
transfer NQSOs to family members, or one or more trusts or other entities for the benefit of or owned by family members, consistent with the applicable securities laws, according to such terms as the Committee may determine; provided that the
Participant receives no consideration for the transfer of a NQSO and the transferred NQSO shall continue to be subject to the same terms and conditions as were applicable to the NQSO immediately before the transfer. 

 

	7.	Change in Control Provisions. 

 (a) Assumption of Awards. Upon a Change in Control where the Company is not the surviving corporation (or survives only as a subsidiary of another corporation), unless the Committee determines
otherwise, all outstanding Options and SARs that are not exercised shall be assumed by, or replaced with comparable options or rights by, the surviving corporation (or a parent or subsidiary of the surviving corporation), and other outstanding
Awards shall be converted to similar awards of the surviving corporation (or a parent or subsidiary of the surviving corporation). 
 (b) Other Alternatives. Notwithstanding the foregoing, in the event of a Change in Control, the Committee may take any of the following actions with respect to any or all outstanding Awards:
(i) determine that outstanding Options and SARs shall accelerate and become exercisable, in whole or in part, upon the Change in Control or upon such other event as the Committee determines, (ii) determine that the restrictions and
conditions on outstanding Restricted Shares, Restricted Share Units, Performance Shares and Performance Units shall lapse, in whole or in part, upon the Change in Control or upon such other event as the Committee determines, (iii) determine
that Eligible Persons holding Restricted Share Units, Performance Units, Dividend Equivalents and Other Share-Based Awards shall receive a payment in settlement of such Restricted Share Units, Performance Units, Dividend Equivalents, and Other
Share-Based Awards in an amount determined by the Committee, (iv) require that Participants surrender their outstanding Options and SARs in exchange for a payment by the Company, in cash or stock, as determined by the Committee, in an amount
equal to the amount by which the then Fair Market Value of the Shares subject to the Participant’s unexercised Options and SARs exceeds the exercise price of the Options or the base amount of SARs, as applicable, or (v) after giving
Participants an opportunity to exercise their outstanding Options and SARs, terminate any or all unexercised Options and SARs at such time as the Committee deems appropriate. Such surrender, termination or settlement shall take place as of the date
of the Change in Control or such other date as the Committee may specify. The Committee shall have no obligation to take any of the foregoing actions, and, in the absence of any such actions, outstanding Awards shall continue in effect according to
their terms (subject to any assumption pursuant to subsection (a) above). 
  

	8.	Qualified Performance-Based Compensation. 

 (a) Designation as Qualified Performance-Based Compensation. The Committee may determine that Restricted Shares, Restricted Share Units, Performance Shares, Performance Units, Dividend Equivalents
or Other Share-Based Awards granted to an employee shall be considered “qualified performance-based compensation” under section 162(m) of the Code. The provisions of this Section 8 shall apply to any such Awards that are to be
considered “qualified performance-based compensation” under section 162(m) of the Code. The Committee may also grant Options or SARs under which the exercisability of the Options is subject to achievement of performance goals as described
in this Section 8 or otherwise. 
 (b) Performance Goals. When Restricted Shares, Restricted Share Units,
Performance Shares, Performance Units, Dividend Equivalents or Other Share-Based Awards that are considered to be “qualified performance-based compensation” are granted, the Committee shall establish in writing (i) the

  
 12 

 
objective performance goals that must be met, (ii) the period during which performance will be measured, (iii) the maximum amounts that may be paid if the performance goals are met, and
(iv) any other conditions that the Committee deems appropriate and consistent with the requirements of section 162(m) of the Code for “qualified performance-based compensation.” The performance goals shall satisfy the requirements for
“qualified performance-based compensation,” including the requirement that the achievement of the goals be substantially uncertain at the time they are established and that the performance goals be established in such a way that a third
party with knowledge of the relevant facts could determine whether and to what extent the performance goals have been met. As to Awards identified by the Committee as “qualified performance-based compensation,” the Committee shall not have
discretion to increase the amount of compensation that is payable, but may reduce the amount of compensation that is payable upon achievement of the designated performance goals. 

(c) Criteria Used for Objective Performance Goals. The Committee shall use objectively determinable performance goals based on one
or more of the following criteria: stock price, earnings per share, price-earnings multiples, net earnings, operating earnings, revenue, number of days sales outstanding in accounts receivable, productivity, margin, EBITDA (earnings before interest,
taxes, depreciation and amortization), net capital employed, return on assets, shareholder return, return on equity, return on capital employed, growth in assets, unit volume, sales, cash flow, market share, relative performance to a comparison
group designated by the Committee, or strategic business criteria consisting of one or more objectives based on meeting specified revenue goals, market penetration goals, customer growth, geographic business expansion goals, cost targets or goals
relating to acquisitions or divestitures. The performance goals may relate to one or more business units or the performance of the Company as a whole, or any combination of the foregoing. Performance goals need not be uniform as among Participants.

 (d) Timing of Establishment of Goals. The Committee shall pre-establish the performance goals in writing either before
the beginning of the performance period or during a period ending no later than the earlier of (i) 90 days after the beginning of the performance period or (ii) the date on which 25% of the performance period has been completed, or such
other date as may be required or permitted under applicable regulations under section 162(m) of the Code, provided that the outcome is substantially uncertain at the time of the Committee actually established the goal. 

(e) Certification of Results. The Committee shall certify the performance results for the performance period specified in the
Award Agreement after the performance period ends. The Committee shall determine the amount, if any, to be paid pursuant to each Award based on the achievement of the performance goals and the satisfaction of all other terms of the Award Agreement.

 (f) Death, Disability or Other Circumstances. The Committee may provide in the Award Agreement that Awards under this
Section 8 shall be payable, in whole or in part, in the event of the Participant’s death or disability, a Change in Control or under other circumstances consistent with the Treasury regulations and rulings under section 162(m) of the Code.

  

	9.	General Provisions. 

 (a)
Compliance with Legal and Trading Requirements.  
 (i) The Plan, the granting and exercising of Awards
thereunder, and the other obligations of the Company under the Plan and any Award Agreement, shall be subject to all applicable Irish law, US federal, state and other applicable laws, rules and regulations, and to such approvals by any stock
exchange, regulatory or governmental agency as may be required. The Company, in its discretion, may postpone the issuance or delivery of Shares under any Award until completion of such stock exchange or market system listing or registration or
qualification of such Shares or any required action under any Irish law, US state, federal or other applicable law, rule or regulation as the Company may consider appropriate, and may require any Participant to make such representations and furnish
such information as it may consider appropriate in connection with the issuance or delivery of Shares in compliance with applicable laws, rules and regulations. No provisions of the Plan shall be interpreted or construed to obligate the Company to
register any Shares under Irish law, US federal or state law or other applicable law. The Shares issued under the Plan may be subject to such other restrictions on transfer as determined by the Committee. 

  
 13 

 (ii) With respect to persons subject to section 16 of the Exchange Act, it
is the intent of the Company that the Plan and all transactions under the Plan comply with all applicable provisions of Rule 16b-3 or its successors under the Exchange Act. In addition, it is the intent of the Company that ISOs comply with the
applicable provisions of section 422 of the Code, and Awards of “qualified performance-based compensation” comply with the applicable provisions of section 162(m) of the Code. To the extent that any legal requirement of section 16 of the
Exchange Act or section 422 or 162(m) as set forth in the Plan ceases to be required under section 16 of the Exchange Act or section 422 or 162(m) of the Code, that Plan provision shall cease to apply. The Committee may revoke any Award if it is
contrary to law or modify a Award to bring it into compliance with any valid and mandatory government regulation. The Committee may also adopt rules regarding the withholding of taxes on payments to Participants. The Committee may, in its sole
discretion, agree to limit its authority under this Section. 
 (b) No Right to Continued Employment or Service. Neither
the Plan nor any action taken thereunder shall be construed as giving any employee, consultant or director the right to be retained in the employ or service of the Company or any of its Subsidiaries or Affiliates, nor shall it interfere in any way
with any right of the Company or any of its Subsidiaries or Affiliates to terminate any employee’s, consultant’s or director’s employment or service at any time, subject to applicable law. 

(c) Taxes. The Company or any Subsidiary or Affiliate is authorized to withhold from any Award granted, any payment relating to an
Award under the Plan, including from a distribution of Shares, or any payroll or other payment to an Eligible Person, amounts of minimum withholding and other taxes due in connection with any transaction involving an Award, and to take such other
action as the Committee may deem necessary or advisable under applicable laws to enable the Company and Eligible Persons to satisfy obligations for the payment of withholding taxes and other tax obligations relating to any Award. This authority
shall include authority to withhold or receive Shares or other property and to make cash payments in respect thereof in satisfaction of an Eligible Person’s tax obligations; provided, however, that the amount of tax withholding to be satisfied
by withholding Shares shall be limited to the minimum amount of taxes, including employment taxes, required to be withheld under applicable Irish law, US federal, state and other applicable law. 

(d) Changes to the Plan and Awards. The Board may amend, alter, suspend, discontinue, or terminate the Plan or the
Committee’s authority to grant Awards under the Plan without the consent of shareholders of the Company or Participants, except that any such amendment or alteration shall be subject to the approval of the Company’s shareholders to the
extent such shareholder approval is required under (i) the rules of any stock exchange or automated quotation system on which the Shares may then be listed or quoted, (ii) the Act, (iii) section 162(m) of the Code or (iv) as it
applies to ISOs, to the extent such shareholder approval is required under section 422 of the Code; provided, however, that, without the consent of an affected Participant, no amendment, alteration, suspension, discontinuation, or termination of the
Plan may materially and adversely affect the rights of such Participant under any Award theretofore granted to him or her. The Committee may waive any conditions or rights under, amend any terms of, or amend, alter, suspend, discontinue or
terminate, any Award theretofore granted, prospectively or retrospectively; provided, however, that, without the consent of a Participant, no amendment, alteration, suspension, discontinuation or termination of any Award may materially and adversely
affect the rights of such Participant under any Award theretofore granted to him or her. Notwithstanding any provision to the contrary herein, the Plan and any Award Agreements issued under the Plan may be amended, without the consent of a
Participant, in any respect deemed by the Board or the Committee to be necessary in order to preserve compliance with, or perfect an exemption from, section 409A of the Code. 
 (e) No Rights to Awards; No Shareholder Rights. No Eligible Person or employee shall have any claim to be granted any Award under the Plan, and there is no obligation for uniformity of treatment of
Eligible Persons and employees. No Award shall confer on any Eligible Person any of the rights of a shareholder of the Company unless and until Shares are duly issued or transferred to the Eligible Person in accordance with the terms of the Award.

  
 14 

 (f) Unfunded Status of Awards. The Plan is intended to constitute an
“unfunded” plan for incentive compensation. With respect to any payments not yet made to a Participant pursuant to an Award, nothing contained in the Plan or any Award shall give any such Participant any rights that are greater than those
of a general creditor of the Company; provided, however, that the Committee may authorize the creation of trusts or make other arrangements to meet the Company’s obligations under the Plan to deliver cash, Shares, other Awards, or other
property pursuant to any Award, which trusts or other arrangements shall be consistent with the “unfunded” status of the Plan unless the Committee otherwise determines with the consent of each affected Participant. 

(g) Nonexclusivity of the Plan. Neither the adoption of the Plan by the Board nor its submission to the shareholders of the
Company for approval shall be construed as creating any limitations on the power of the Board to adopt such other incentive arrangements as it may deem desirable, including, without limitation, the granting of options and other awards otherwise than
under the Plan, and such arrangements may be either applicable generally or only in specific cases. 
 (h) Not Compensation
for Benefit Plans. No Award payable under this Plan shall be deemed salary or compensation for the purpose of computing benefits under any benefit plan or other arrangement of the Company for the benefit of its employees, consultants or
directors unless the Company shall determine otherwise. 
 (i) No Fractional Shares. No fractional Shares shall be issued
or delivered pursuant to the Plan or any Award. The Committee shall determine whether cash, other Awards, or other property shall be issued or paid in lieu of such fractional Shares or whether such fractional Shares or any rights thereto shall be
forfeited or otherwise eliminated. 
 (j) Employees Subject to Taxation outside the United States. With respect to
Participants who are subject to taxation in countries other than the United States, the Committee may make Awards on such terms and conditions as the Committee deems appropriate to comply with the laws of the applicable countries, and the Committee
may create such procedures, addenda and subplans and make such modifications as may be necessary or advisable to comply with such laws. 
 (k) Company Policies. All Awards granted under the Plan shall be subject to any applicable clawback or recoupment policies, share trading policies and other policies that may be implemented by the
Board from time to time. 
 (l) Governing Law. The validity, construction, and effect of the Plan, any rules and
regulations relating to the Plan, and any Award Agreement shall be determined in accordance with the laws of Ireland, without giving effect to principles of conflict of laws thereof. 

(m) Effective Date; Plan Termination. The Plan shall be effective on the date that the spin-off of Prothena Corporation plc from
Elan Corporation plc is first effective (the “Effective Date”), provided that the Plan has been approved by the Company’s shareholders prior to that date. The Plan shall terminate as to future awards on the date which is ten
(10) years after the Effective Date. 
 (n) Section 409A. The Plan is intended to comply with section 409A of
the Code, or an exemption, and payments may only be made under the Plan upon an event and in a manner permitted by section 409A of the Code, to the extent applicable. Notwithstanding anything in this Plan to the contrary, if required by section 409A
of the Code, if a Participant is considered a “specified employee” for purposes of section 409A and if payment of any Award under this Plan is required to be delayed for a period of six months after “separation from service”
within the meaning of section 409A of the Code, payment of such Award shall be delayed as required by section 409A, and the accumulated amounts with respect to such Award shall be paid in a lump sum payment within ten (10) days after the end of
the six (6) month period. If the Participant dies during the postponement period prior to the payment of benefits, the amounts 

  
 15 

 
withheld on account of section 409A shall be paid to the Participant’s Beneficiary within sixty (60) days after the date of the Participant’s death. For purposes of section 409A of
the Code, each payment under the Plan shall be treated as a separate payment. In no event shall a Participant, directly or indirectly, designate the calendar year of payment. To the extent that any provision of the Plan would cause a conflict with
the requirements of section 409A of the Code, or would cause the administration of the Plan to fail to satisfy the requirements of section 409A, such provision shall be deemed null and void to the extent permitted by applicable law. Notwithstanding
anything in the Plan or any Award Agreement to the contrary, each Participant shall be solely responsible for the tax consequences of Awards under the Plan, and in no event shall the Company have any responsibility or liability if an Award does not
meet any applicable requirements of section 409A of the Code. Although the Company intends to administer the Plan to prevent taxation under section 409A of the Code, the Company does not represent or warrant that the Plan or any Award complies with
any provision of Federal, state, local or other tax law. 
 (o) Titles and Headings. The titles and headings of the
sections in the Plan are for convenience of reference only. In the event of any conflict, the text of the Plan, rather than such titles or headings, shall control. 

  
 16Prothena Biosciences Inc Severance Plan

 Exhibit 10.5 
 PROTHENA BIOSCIENCES INC 

SEVERANCE PLAN 

 TABLE OF CONTENTS 

 

					
	 	  	Page	 
	ARTICLE I INTRODUCTION	  	 	1	  
		
	ARTICLE II DEFINITIONS	  	 	1	  
		
	ARTICLE III ELIGIBILITY	  	 	5	  
		
	ARTICLE IV PAY AND BENEFITS IN LIEU OF WARN NOTICE	  	 	7	  
		
	ARTICLE V SEVERANCE PAY AND SEVERANCE BENEFITS	  	 	7	  
		
	ARTICLE VI WAIVER AND RELEASE AGREEMENT	  	 	11	  
		
	ARTICLE VII PLAN ADMINISTRATION	  	 	11	  
		
	ARTICLE VIII PROCEDURES FOR MAKING AND APPEALING CLAIMS FOR
PLAN BENEFITS	  	 	12	  
		
	ARTICLE IX AMENDMENT/TERMINATION/VESTING	  	 	14	  
		
	ARTICLE X NO ASSIGNMENT	  	 	14	  
		
	ARTICLE XI CONFIDENTIAL INFORMATION/COOPERATION	  	 	14	  
		
	ARTICLE XII MISCELLANEOUS PROVISIONS	  	 	15	  

 PROTHENA BIOSCIENCES INC 

SEVERANCE PLAN 
 ARTICLE I 
 INTRODUCTION 

The Company has adopted this Plan, for the benefit of certain “Eligible Employees” of the Company and certain Affiliates
specified by the Company, effective as of the Effective Date. The Plan is intended to apply to United States based “Employees,” as described herein. The Plan shall be binding on any successor to all or substantially all of
the Company’s assets or business. 
 The Plan is an unfunded welfare benefit plan for purposes of the ERISA. Except as
otherwise provided herein, the Plan supersedes any prior formal or informal severance plans, programs or policies of the Company or its Affiliates covering Eligible Employees. The Plan operates on a calendar year. 

ARTICLE II 
 DEFINITIONS 
 2.1. “Act” means the Irish
Companies Act 1963, as amended from time to time. References to any provision of the Act shall be deemed to include successor provisions thereto and regulations thereunder. 
 2.2. “Affiliate” means any member of the group of corporations, trades or businesses or other organizations comprising the “controlled group” with the Company under Code
Section 414. 
 2.3. “Base Compensation” means an Eligible Employee’s highest rate of base
compensation during the thirteen (13) months prior to the date of the Eligible Employee’s Severance Date. 
 2.4.
“Change in Control” means: 
  

	 	(a)	The consummation of a merger or consolidation of Prothena Corporation plc with or into another entity or any other corporate reorganization (however effected, including
by general offer or court sanctioned compromise, arrangement or scheme under the Act or otherwise), if more than fifty percent (50%) of the combined voting power of the continuing or surviving entity’s issued shares or securities
outstanding immediately after such merger, consolidation or other reorganization is owned by persons who were not shareholders of Prothena Corporation plc immediately prior to such merger, consolidation or other reorganization;

	 	(b)	The sale, transfer or other disposition of all or substantially all of Prothena Corporation plc’s assets; 

 

	 	(c)	Individuals who, as of the date that the Board of Directors of Prothena Corporation plc first consists of at least seven members, constitute the Board of Directors of
Prothena Corporation plc (the “Incumbent Directors”) cease for any reason, including, without limitation, as a result of a tender offer, proxy contest, merger or similar transaction, to constitute at least a majority of the Board of
Directors of Prothena Corporation plc; provided, however, that any individual who becomes a director of Prothena Corporation plc subsequent to the date that the Board of Directors of Prothena Corporation plc first consists of at least seven members
shall be considered an Incumbent Director if such person’s election or nomination for election was approved by a vote of at least a majority of the Incumbent Directors; but, provided further that any such person whose initial assumption of
office is in connection with an actual or threatened solicitation of proxies or consents by or on behalf of a person other than the Board of Directors of Prothena Corporation plc, including by reason of agreement intended to avoid or settle any such
actual or threatened contest or solicitation, shall not be considered an Incumbent Director; 

  

	 	(d)	A transaction as a result of which a person or company obtains the ownership directly or indirectly of the ordinary shares in Prothena Corporation plc carrying more
than fifty percent (50%) of the total voting power represented by Prothena Corporation plc’s issued share capital in pursuance of a compromise or arrangement sanctioned by the court under section 201 of the Act or becomes bound or entitled
to acquire ordinary shares in Prothena Corporation plc under section 204 of the Act; or 

  

	 	(e)	Any transaction as a result of which any person becomes the “beneficial owner” (as defined in Rule 13d-3 under the Exchange Act), directly or indirectly, of
securities of Prothena Corporation plc representing at least fifty percent (50%) of the total voting power represented by Prothena Corporation plc’s then outstanding voting securities (e.g., issued shares). For purposes of this subsection
(e), the term “person” shall have the same meaning as when used in sections 13(d) and 14(d) of the Exchange Act but shall exclude (i) a trustee or other fiduciary holding securities under an employee benefit plan of Prothena
Corporation plc or of any subsidiary of Prothena Corporation plc and (ii) a company owned directly or indirectly by the shareholders of Prothena Corporation plc in substantially the same proportions as their ownership of the ordinary shares of
Prothena Corporation plc. 

  

	 	(f)	 Notwithstanding the foregoing, in the case of any amounts payable under the Plan that constitute deferred compensation subject to Code
Section 409A, the definition of “Change in Control” set forth above shall not apply, and the term “Change in Control” shall instead mean a “change in the ownership or effective control” of Prothena Corporation plc
or “in the ownership of a substantial portion 

  
 2 

	 	
of the assets” of Prothena Corporation plc within the meaning of Code Section 409A(a)(2)(A)(v) and the regulations and guidance issued thereunder, but only to the extent this substitute
definition is necessary in order for the payments to comply with the requirements prescribed by Code Section 409A. 

 2.5. “Code” means the Internal Revenue Code of 1986, as amended. 

2.6. “Company” means Prothena Biosciences Inc. 
 2.7. “Comparable Position” means a position either with the Company or any of its Affiliates or with a successor or transferee of all or a part of the business of the Company or
Affiliate, on terms which do not cause a Significant Reduction in Scope or Base Compensation and do not entail a Relocation. The Plan Administrator, in its sole discretion, will determine whether a position is a Comparable Position. 

2.8. “Confidential Information” means trade secrets and other propriety information of an Employer or any Affiliate. If
an Eligible Employee entered into a separate confidentiality or proprietary rights agreement with an Employer or any Affiliate, the term “Confidential Information” for purposes of this Plan shall have the meaning ascribed to any such term
or concept as it is defined under, or used in, the separate agreement. 
 2.9. “Effective Date” means the date
that the spin-off of Prothena Corporation plc from Elan Corporation plc is first effective. 
 2.10. “Eligible
Employee” means each Employee who is not (i) covered by a written employment agreement that contains a severance provision, or covered by a written severance agreement (for the duration of that agreement); (ii) classified as
“temporary,” including without limitation, anyone classified as an “intern” or “co-op”; (iii) a consultant; (iv) a “leased employee” as defined in Code Section 414(n); or (v) a person
performing services for an Employer on a contract basis or as an independent contractor or consultant or through a purchase order, supplier agreement or any other form of agreement that the Employer enters into for services, regardless of whether
any of the above such individuals set forth in (iii), (iv) or (v) are subsequently determined by the Internal Revenue Service, the U.S. Department of Labor or a court to be Employees. 

2.11. “Employee” means any full-time or part-time employee of an Employer who regularly works thirty (30) hours or
more per calendar week for the Employer. 
 2.12. “Employer” means the Company and each Affiliate identified on
Attachment A, including the wholly-owned subsidiaries of the Affiliates identified on Attachment A. 
 2.13.
“ERISA” means the Employee Retirement Income Security Act of 1974, as amended. 
 2.14. “Exchange
Act” means the Securities Exchange Act of 1934, as amended. 

  
 3 

 2.15. “Executive Employee” means an Eligible Employee who was in Band VII
and higher or any other title ranked at or higher than Senior Vice President, in each case, as of the date immediately prior to the Effective Date. 
 2.16. “Involuntary Termination” means a termination of an Eligible Employee’s employment by the Employer due to a business condition, as determined in the sole discretion of the
Employer. The term Involuntary Termination shall include (i) a termination effective when the Eligible Employee exhausts a leave of absence during, or at the end of, a WARN Notice Period and (ii) a situation where an Eligible Employee on
an approved leave of absence during which the Employee’s position is protected under applicable law (e.g., a leave under the Family Medical Leave Act), returns from such leave, and cannot be placed in employment with the Employer. 

2.17. “Plan” means the Prothena Biosciences Inc Severance Plan, as set forth in this instrument and as hereafter
amended. 
 2.18. “Relocation” means a material change in the geographic location at which the Eligible
Employee is required to perform services. Such change in an Eligible Employee’s primary job site will be considered material if (i) for Eligible Employees other than field-based sales representatives (or similar field-based positions), the
new location increases the Eligible Employee’s commute between home and primary job site by at least thirty (30) miles, or (ii) in the Company’s reasonable opinion, the new location requires that the Eligible Employee move
his/her home to a new location at least thirty (30) miles away from the Eligible Employee’s home immediately prior to the change. 
 2.19. “Severance Date” means the final day of employment with the Employer which date shall be communicated in writing by the Employer to the Employee. 

2.20. “Significant Reduction in Scope or Base Compensation” means a material diminution in the Eligible Employee’s
authority, duties, or responsibilities or a material diminution in the Eligible Employee’s base compensation. For purposes herein, a material diminution in the Eligible Employee’s authority, duties, or responsibilities and a material
diminution in the Eligible Employee’s base compensation shall be measured in comparison to the Eligible Employee’s authority, duties, or responsibilities and the Eligible Employee’s base compensation, respectively, on the Effective
Date. The Plan Administrator, in its sole discretion, shall determine whether an Eligible Employee experiences a “Significant Reduction.” 
 2.21. “Target Bonus” means an Eligible Employee’s highest target annual bonus rate during the thirteen (13) months prior to the date of the Eligible Employee’s Severance
Date. 
 2.22. “Triggering Event” means an Involuntary Termination, Relocation or Significant Reduction in
Scope or Base Compensation. 
 2.23. “WARN Notice Date” means the date the Employer is required to notify an
Eligible Employee pursuant to the WARN Act or similar state law that he/she is to be terminated from employment with the Employer in conjunction with a “plant closing” or “mass layoff” as described in the WARN Act or similar
state law. 

  
 4 

 2.24. “WARN Notice Period” means the sixty (60) consecutive calendar
day period, or other applicable period under similar state law, commencing on an Eligible Employee’s WARN Notice Date. 

2.25. “Week of Pay” shall be determined based on the Eligible Employee’s status as a salaried or hourly Employee.
If the Eligible Employee is a salaried Employee, Week of Pay shall be the Eligible Employee’s weekly Base Compensation. If the Eligible Employee is an hourly Employee, Week of Pay shall be the Eligible Employee’s hourly Base Compensation
multiplied by his/her regularly scheduled number of hours worked per week at the highest weekly level in effect during the thirteen (13) months prior to the Eligible Employee’s Severance Date. If the Eligible Employee works part-time,
his/her Week of Pay is determined on a prorated basis by calculating his/her average number of hours per week actually worked during the prior Year of Service. 
 2.26. “Years of Service” shall be determined in accordance with the Employer’s personnel records. An Eligible Employee shall receive credit for a Year of Service for each twelve
(12) month period of active service with the Employer. For partial years of employment, the Eligible Employee shall receive credit for a full Year of Service if he/she completes at least six (6) full months of active service. If an
Eligible Employee has not completed at least six (6) full months of active service during a partial year, he/she shall not receive credit for a Year of Service. 
 ARTICLE III 
 ELIGIBILITY 

3.1. Conditions of Eligibility. To be eligible for benefits as described in Article V, the Eligible Employee must (i) remain
an Employee through the Severance Date, (ii) through the Severance Date, fulfill the normal responsibilities of his/her position, including meeting regular attendance, workload and other standards of the Employer, as applicable, and
(iii) submit the signed Waiver and Release Agreement required by the Plan Administrator on, or within forty-five (45) days after, his/her Severance Date or receipt of the Waiver and Release Agreement (whichever occurs later) and not revoke
the signed Waiver and Release Agreement. In addition, in the event of a Relocation or a Significant Reduction in Scope or Base Compensation, the Eligible Employee must provide his/her Employer with written notice within ninety (90) days after
the occurrence of such event. The Employer shall then have thirty (30) days to cure such event. 
 3.2. Conditions of
Ineligibility. An otherwise Eligible Employee shall not receive severance pay or severance benefits under the Plan if: 
  

	 	(a)	the Employee ceases to be an Eligible Employee as defined by the Plan; 

  

	 	(b)	the Employee terminates employment with the Employer by reason of death; 

  
 5 

	 	(c)	the Employer terminates the Employee’s employment for one or more of the following reasons (determined in the sole discretion of the Plan Administrator):
Commission by the Employee of an act of fraud, theft, misappropriation of funds, dishonesty, bad faith or disloyalty; violation by the Employee of any federal, state, local law or regulation; violation by the Employee of any rule, regulation or
policy of the Employer or other job related misconduct; failure to perform the duties of the position held by such Employee in a manner which satisfies the reasonable expectations of the Employer; failure by the Employee to meet any requirement
reasonably imposed upon such Employee by the Employer as a condition of continued employment; or dereliction or neglect by the Employee in the performance of such Employee’s job duties; 

 

	 	(d)	the Employee terminates employment with the Employer through job abandonment; 

 

	 	(e)	other than as set forth in Section 2.14(ii), the individual is no longer an Employee and is receiving long-term disability benefits from the Employer (as
determined under the applicable Employer-sponsored long-term disability plan) as of the date the Triggering Event would have occurred had the individual been an Employee on such date; 

 

	 	(f)	the Employee is employed in an operation, division, department or facility, that is sold, leased or otherwise transferred, in whole or in part, from an Employer, and
(i) the Employee accepts any position with the new owner/operator, or (ii) the Employee is offered a Comparable Position by the new owner/operator; 

 

	 	(g)	the Employee gives notice of his/her voluntary termination (other than as provided in Section 2.19) prior to his/her Severance Date or the effective date of a
sale, lease or transfer of an operation, division, department or facility, as described in Section 3.2(f), regardless of the effective date of such termination; 

 

	 	(h)	the Employee ceases working with the Employer and receives severance benefits under the terms of another group reorganization/restructuring benefit plan or severance
program sponsored by the Employer; 

  

	 	(i)	the Employee is offered a Comparable Position from an Employer, or accepts any position with an Employer, even if it is not a Comparable Position;

  

	 	(j)	the Employee experiences a Triggering Event after the Plan is terminated; 

  

	 	(k)	the Employee does not timely execute and return to the Plan Administrator a valid Waiver and Release Agreement; 

 

	 	(l)	 the Employee works primarily in an office located in a country other than the United States and is entitled to severance benefits under the laws of
such country or the policies of the company at which he/she is based and such severance benefits may not be waived; or 

  
 6 

	 	(m)	the Employee is offered a Comparable Position by, or accepts any position with, an employer with which the Company or any of its Affiliates has reached an agreement or
arrangement under which the employer agrees to offer employment to the otherwise Eligible Employee. 

 The
foregoing list of conditions is intended to be illustrative and may not be all inclusive; the Plan Administrator will determine in the Plan Administrator’s sole discretion whether an Eligible Employee is eligible for severance pay and severance
benefits under the Plan. 
 ARTICLE IV 
 PAY AND BENEFITS IN LIEU OF WARN NOTICE 

4.1. Wage Payments. If an Eligible Employee is entitled to advance notice of a “plant closing” or a “mass
layoff” under the WARN Act or similar state law, but experiences a Triggering Event before the end of a WARN Notice Period, the Eligible Employee shall be entitled to receive Weeks of Pay until the end of the WARN Notice Period as if he/she
were still employed through such date. The Weeks of Pay under this Section 4.1 will be issued according to the normal payroll practices of the Employer and shall not be subject to the Waiver and Release Agreement. 

4.2. Benefits. An Eligible Employee described in Section 4.1 shall be entitled to benefits under an Employer-sponsored
medical, dental and vision benefit plans, as amended from time to time, through the end of the WARN Notice Period on the same terms and under the same conditions as applied to the Eligible Employee immediately prior to the Triggering Event. The
benefits under this Section 4.2 are not subject to the Waiver and Release Agreement. 
 ARTICLE V 

SEVERANCE PAY AND SEVERANCE BENEFITS 

5.1. Generally. In exchange for providing the Employer with an enforceable Waiver and Release Agreement, in a form acceptable to
the Plan Administrator, an Eligible Employee who terminates employment on account of a Triggering Event shall be eligible to receive severance pay and severance benefits as described below and subject to the other provisions of this Plan. The
consideration for the voluntary Waiver and Release Agreement shall be the severance pay and severance benefits the Eligible Employee would not otherwise be eligible to receive. 

5.2. Severance Pay. Severance pay shall be determined in accordance with the table below based on the Eligible Employee’s
“Band” classification immediately prior to the Effective Date and in accordance with the terms hereof. If the applicable Triggering Event occurs on or within two (2) years following a Change in Control and the Eligible Employee was an
Employee at the time of the Change in Control, the Eligible Employee’s severance pay shall be determined under the column in the table below titled “Change in Control Severance Pay” and shall be paid

  
 7 

 
in accordance with the terms hereof. The Band applicable to any Eligible Employee shall be determined by the Plan Administrator, in its sole discretion, based on the Eligible Employee’s job
position relative to the job grading system in place for the applicable Employer. 
  

					
	 Employment

Classification

Immediately
 prior to
the
 Effective
Date
	  	 Severance Pay prior to a Change in Control
	  	 Change in Control Severance Pay

			
	 Band I
	  	Six (6) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of Service, limited to a maximum period of thirty-nine (39) Weeks of Pay.	  	Same as severance pay
			
	 Band II
	  	Nine (9) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of Service, limited to a maximum period of thirty-nine (39) Weeks of Pay.	  	Same as severance pay
			
	 Band III
	  	Fifteen (15) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of Service, limited to a maximum period of forty-five (45) Weeks of Pay.	  	Same as severance pay
			
	 Band IV
	  	Fifteen (15) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of Service, limited to a maximum period of forty-five (45) Weeks of Pay.	  	Same as severance pay
			
	 Band V
	  	Twenty-four (24) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of Service, limited to a maximum period of fifty-two (52) Weeks of Pay.	  	The greater of (i) severance pay described at left or (ii) twenty-six (26) Weeks of Pay plus an amount equal to the Eligible Employee’s Target Bonus.
			
	 Band VI
	  	Fifty-two (52) Weeks of Pay.*	  	Seventy-eight (78) Weeks of Pay plus an amount equal to the Eligible Employee’s Target Bonus.
			
	 Band VII
	  	Fifty-two (52) Weeks of Pay plus an amount equal to the Eligible Employee’s Target Bonus.*	  	Two times (2x) the sum of (a) fifty-two weeks (52) Weeks of Pay (prior to any reduction due to a Significant Reduction in Scope or Base Compensation, if applicable) and (b) the
Eligible Employee’s Target Bonus.

  
 8 

					
			
	 Band VIII and

higher
	  	Seventy-eight (78) Weeks of Pay plus an amount equal to the Eligible Employee’s Target Bonus.	  	Two and one half times (2.5x) the sum of (a) fifty-two weeks (52) Weeks of Pay (prior to any reduction due to a Significant Reduction in Scope or Base Compensation, if applicable)
and (b) the Eligible Employee’s Target Bonus.

 * Eligible Employees in Bands VI and VII who had been continuously employed by Athena Neurosciences, Inc,
Elan Pharmaceuticals, Inc., Elan Drug Delivery, Inc., Elan Holdings, Inc. from April 1, 2011 through the Effective Date shall be eligible to receive thirty-six (36) Weeks of Pay plus two (2) additional Weeks of Pay for each Year of
Service, limited to a maximum period of seventy-eight (78) Weeks of Pay, if such amount provides a greater benefit to such Eligible Employee than that described in the table above. 

Severance pay shall be paid in a lump sum payment within seventy-five (75) days following the Severance Date. Notwithstanding the
foregoing, any severance pay and severance benefits which become payable shall be paid only if the Eligible Employee has executed and not revoked a signed Waiver and Release Agreement prior to the payment. All legally required taxes and any sums
owed the Employer shall be deducted from Plan severance pay. 
 If an Employer reemploys an Eligible Employee who is receiving
or has received severance pay and benefits under the Plan, the individual shall become ineligible and such pay and benefits shall cease effective as of the reemployment date. Further, the former Eligible Employee must repay the portion of the
severance pay attributable to the period that begins on the date the Eligible Employee was reemployed. If the Plan Administrator, in its sole discretion, determines that the former Eligible Employee’s services address a critical business need,
then the Plan Administrator may provide that no such repayment is required. 
 5.3. Severance Benefits. 

(a) Medical, Dental and Vision Benefits Coverage Continuation. Under federal health care continuation coverage law (referred to as
“COBRA”), the Eligible Employee who is receiving health care coverage under an Employer-sponsored plan is entitled to elect health care continuation coverage under the applicable Employer health plan if his/her employment terminates
for certain reasons. Any of the Triggering Events would qualify the Eligible Employee to receive such continuation coverage, subject to the terms of the applicable health plan and governing law. If an Eligible Employee experiences a Triggering Event
before his/her WARN Notice Period (if applicable) expires, his/her COBRA rights begin when the WARN Notice Period expires. 
 If
an Eligible Employee elects to exercise his/her applicable COBRA continuation rights under the Employer health plan, for the lesser of six (6) months or the applicable Benefit Continuation Period (as defined below), the Eligible Employee will
only be required to pay the same share of the applicable premium that would apply if he/she were participating in the applicable Employer health plan as an active employee. For the balance of the Benefit

  
 9 

 
Continuation Period, if any, the Eligible Employee will be required to pay the full monthly COBRA premium. On a monthly basis, the Employer will reimburse the Eligible Employee for the full cost
of the COBRA premiums paid, less the amount that would apply if he/she were participating in the applicable Employer health plan as an active employee. For purposes of the Plan, “Benefit Continuation Period” shall mean for Eligible
Employees in Bands I through V, the period of time following the Severance Date in which the Eligible Employee is entitled to receive regular severance pay under the Plan (regardless of whether the Eligible Employee is entitled to Change in Control
severance pay) not to exceed six (6) months; for Eligible Employees in Band VI and VII, twelve (12) months; and for Eligible Employees in Band VIII or higher, eighteen (18) months. Any partial month will be rounded up to the next
whole month. 
 All of the terms and conditions of an Employer-sponsored medical, dental and vision benefit plans, as amended
from time to time, shall be applicable to an Eligible Employee (and his/her eligible dependents, if applicable) participating in any form of continuation coverage under a Employer-sponsored medical, dental and vision benefit plans. This Plan is not
to be interpreted to expand an Eligible Employee’s health care continuation rights under COBRA. 
 (b) Career Transition
Assistance. A career transition assistance firm selected and paid for by an Employer shall provide career transition assistance. An Eligible Employee must begin the available career transition assistance services within sixty (60) days
following his/her Severance Date. 
 Subject to the limitations set forth above, career transition assistance shall be provided
in accordance with the following table, provided that, to the extent these programs are not available following the Effective Date, substantially comparable career transition assistance shall be provided: 

 

			
	 Employment
 Classification
	  	 Career Transition Services

	 Band I
	  	QuickLaunch or reasonably equivalent program.
		
	 Band II
	  	One month Powerstart Program or reasonable equivalent.
		
	 Band III
	  	Three-month executive program.
		
	 Band IV
	  	Six-month executive program.
		
	 Band V
	  	Nine-month executive program.
		
	 Band VI
	  	Twelve-month executive program.
		
	 Bands VII and higher
	  	Twelve-month Key Executive Program.

 5.4. Taxes. If any payment or benefit the Eligible Employee would receive pursuant to this Plan
(“Payment”) would (a) constitute a “Parachute Payment” within the meaning of Code Section 280G, and (b) but for this sentence, be subject to the excise tax imposed by Code Section 4999 (the
“Excise Tax”), then such Payment shall be equal to the Reduced Amount. The “Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no

  
 10 

 
portion of the Payment being subject to the Excise Tax or (y) the largest portion, up to and including the total of the Payment, whichever amount, after taking into account all applicable
federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in the Eligible Employee’s receipt, on an after-tax basis, of the greatest economic benefit
notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in payments or benefits constituting Parachute Payments is necessary so that the Payment equals the Reduced Amount, reduction shall occur in the
manner that results in the greatest economic benefit for the Eligible Employee. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata. 

ARTICLE VI 
 WAIVER AND RELEASE AGREEMENT 
 In order to receive the severance pay and severance benefits available under the Plan, an Eligible Employee must submit a signed Waiver and Release Agreement form to the Plan Administrator on or within
forty-five (45) days after his/her Severance Date or receipt of the Waiver and Release Agreement, whichever occurs later. The required Waiver and Release Agreement form is attached to the Summary Plan Description as Attachment III, as the same
may be changed in the Company’s sole discretion. An Eligible Employee may revoke his/her signed Waiver and Release Agreement within seven (7) days of his/her signing the Waiver and Release Agreement. Only with respect to Eligible Employees
whose severance under the Plan is “non-qualified deferred compensation” subject to Section 409A of the Code, notwithstanding any provision of this Plan to the contrary, in no event shall the timing of such Eligible Employee’s
execution of the Waiver and Release Agreement, directly or indirectly, result in the Eligible Employee designating the calendar year of payment, and if a payment that is subject to execution of the Waiver and Release Agreement could be made in more
than one taxable year, payment shall be made in the later taxable year. 
 Any such revocation must be made in writing and must
be received by the Plan Administrator within such seven-(7) day period. An Eligible Employee who timely revokes his/her Waiver and Release Agreement shall not be eligible to receive any severance pay or severance benefits under the Plan.
An Eligible Employee who timely submits a signed Waiver and Release Agreement form and who does not exercise his/her right of revocation shall be eligible to receive severance pay and severance benefits under the Plan. 

Eligible Employees shall be advised to contact their personal attorney at their own expense to review the Waiver and Release Agreement
form if they so desire. 
 ARTICLE VII 
 PLAN ADMINISTRATION 
 The Company
shall designate a committee to serve as the “Plan Administrator” of the Plan and the “named fiduciary” within the meaning of such terms as defined in ERISA. The Plan Administrator shall have full power and discretionary authority
to determine eligibility for Plan severance pay and severance benefits and to construe the terms of the Plan, including, but 

  
 11 

 
not limited to, the making of factual determinations, the determination of all questions concerning benefits and procedures for claim review and the resolution of all other questions arising
under the Plan. Severance pay and severance benefits under the Plan will be payable only if the Plan Administrator determines in the Plan Administrator’s discretion that the Eligible Employee is entitled to them. The decisions of the Plan
Administrator shall be final and conclusive with respect to all questions concerning the administration of this Plan. 
 The
Plan Administrator may delegate to other persons responsibilities for performing certain of the duties of the Plan Administrator under the terms of this Plan and may seek such expert advice as the Plan Administrator deems reasonably necessary with
respect to the Plan. The Plan Administrator shall be entitled to rely upon the information and advice furnished by such delegatees and experts, unless actually knowing such information and advice to be inaccurate or unlawful. The Plan Administrator
shall establish and maintain a reasonable claims procedure, including a procedure for appeal of denied claims. The Plan Administrator has discretionary authority to grant or deny benefits under this Plan. In no event shall an Eligible Employee or
any other person be entitled to challenge a decision of the Plan Administrator in court or in any other administrative proceeding unless and until the claim and appeals procedures established under this Plan have been complied with and exhausted.

 In the event of a group termination, as determined in the sole discretion of the Plan Administrator, the Plan Administrator
shall furnish affected Eligible Employees with such additional information as may be required by law. 
 ARTICLE VIII

 PROCEDURES FOR MAKING AND
APPEALING 
 CLAIMS FOR PLAN BENEFITS

 8.1. Claim for Benefits. It is not necessary that an Eligible Employee apply for severance pay and severance
benefits under the Plan. However, if an Eligible Employee wishes to file a claim for severance pay and severance benefits, such claim must be in writing and filed with the Plan Administrator. If the Eligible Employee does not provide all the
necessary information for the Plan Administrator to process the claim, the Plan Administrator may request additional information and set deadlines for the Eligible Employee to provide that information. Within ninety (90) days after receiving a
claim, the Plan Administrator will: 
  

	 	(a)	either accept or deny the claim completely or partially; and 

  

	 	(b)	notify the claimant of acceptance or denial of the claim. 

 8.2. Benefits Review. If the claim is completely or partially denied, the Plan Administrator will furnish a written notice to the claimant containing the following information: 

 

	 	(a)	specific reasons for the denial; 

  

	 	(b)	specific references to the Plan provisions on which any denial is based; 

  
 12 

	 	(c)	a description of any additional material or information that must be provided by the claimant in order to support the claim and an explanation of why such material or
information is necessary; and 

  

	 	(d)	an explanation of the Plan’s appeal procedures which shall also include a statement of the claimant’s right to bring a civil action under Section 502(a)
of ERISA following a denial of the claim upon review. 

 8.3. Appeal of Denied Claim. A claimant may appeal
the denial of his/her claim and have the Plan Administrator reconsider the decision. The claimant or the claimant’s authorized representative has the right to: 
  

	 	(a)	request an appeal by written request to the Plan Administrator not later than sixty (60) days after receipt of notice from the Plan Administrator denying his
claim; 

  

	 	(b)	review or receive copies, upon request and free of charge, any documents, records or other information “relevant” (within the meaning of Department of Labor
Regulation 2560.503-1(m)(8)) to the claimant’s claim; and 

  

	 	(c)	submit written comments, documents, records and other information relating to his/her claim. 

In deciding a claimant’s appeal the Plan Administrator shall take into account all comments, documents, records and other
information submitted by the claimant relating to the claim, without regard to whether such information was submitted or considered in the initial review of the claim. If the claimant does not provide all the necessary information for the Plan
Administrator to decide the appeal, the Plan Administrator may request additional information and set deadlines for the claimant to provide that information. 
 The Plan Administrator will make a decision with respect to such an appeal within sixty (60) days after receiving the written request for such appeal or, in special circumstances, within one-hundred
twenty (120) days after receiving the written request for such appeal. The claimant will be advised of the Plan Administrator’s decision on the appeal in writing. The notice will set forth (1) the specific reasons for the decision,
(2) specific reference to Plan provisions upon which the decision on the appeal is based, (3) a statement that the claimant is entitled to receive, upon request and free of charge, reasonable access to, and copies of, all documents,
records or other information relevant to the claimant’s claim, and (4) a statement of the claimant’s right to bring a civil action under Section 502(a) of ERISA following a wholly or partially denied claim for benefits.

 In no event shall a claimant or any other person be entitled to challenge a decision of the Plan Administrator in court or in
any other administrative proceeding unless and until the claim and appeal procedures described above have been complied with and exhausted. 

  
 13 

 ARTICLE IX 

AMENDMENT/TERMINATION/VESTING 

Eligible Employees do not have any vested right to severance pay and/or severance benefits under the Plan and the Company reserves the
right, in its sole discretion, to amend or terminate the Plan at any time in writing, signed by an authorized officer of the Company, provided, however, that (i) no amendment nor termination shall reduce severance pay or severance benefits
attributable to a Triggering Event that occurs prior to the date the Plan is amended or terminates, and (ii) any amendment or termination that becomes effective after a Change in Control shall not adversely affect the rights of any Eligible
Employee compared with such Eligible Employee’s rights if his/her employment terminated effective immediately before such amendment or termination became effective. 
 The Plan shall be effective only with respect to Triggering Events that occur on or before December 31, 2013. The Company may extend the Plan in its sole discretion. 

ARTICLE X 
 NO ASSIGNMENT 
 Severance pay and
severance benefits payable under the Plan shall not be subject to anticipation, alienation, pledge, sale, transfer, assignment, garnishment, attachment, execution, encumbrance, levy, lien, or charge, and any attempt to cause such severance pay and
severance benefits to be so subjected shall not be recognized, except to the extent required by law. 
 ARTICLE XI

 CONFIDENTIAL INFORMATION/COOPERATION 

Recognizing that the disclosure or improper use of Confidential Information will cause serious and irreparable injury to an Employer,
Eligible Employees with such access acknowledge that (i) they will not at any time, directly or indirectly, disclose Confidential Information to any third party or otherwise use such Confidential Information for their own benefit or the benefit
of others and (ii) in addition to any other remedy permissible by law, payment of severance pay and severance benefits under the Plan shall cease if an Eligible Employee discloses or improperly uses such Confidential Information. Any Eligible
Employee subject to an individual confidentiality agreement or proprietary rights agreement with an Employer or any Affiliate will be deemed to violate the terms of this Article XI if he/she violates the terms of the individual confidentiality
agreement or proprietary rights agreement. 
 Subject to the terms of the Waiver and Release Agreement, each Eligible Employee
shall cooperate with any Employer and its legal counsel in connection with any current or future investigation or litigation relating to any matter to which the Eligible Employee was involved or of which the Eligible Employee has knowledge or
which occurred during the Eligible Employee’s employment. Such assistance shall include, but not be limited to, depositions and testimony and shall continue until such matters are resolved. In addition, an Eligible Employee shall not in any way
disparage any Employer nor any person associated with an Employer to any person, corporation, or other entity. 

  
 14 

 ARTICLE XII 

MISCELLANEOUS PROVISIONS 

12.1. Return of Property. In order for an Eligible Employee to commence receiving severance pay and severance benefits under the
Plan, (i) he/she shall be required to return all Employer property (including, but not limited to, Confidential Information, client lists, keys, credit cards, documents and records, identification cards, equipment, laptop computers, software,
and pagers), and (ii) repay any outstanding bills, advances, debts, amounts due to an Employer, as of his/her Severance Date. To the extent the Eligible Employee has any Employer property stored electronically (including, but not limited to, in
the form of email) on his/her personal computer, in a personal email account, on a personal storage device, or otherwise, such Eligible Employee shall promptly provide copies of all such information to the Employer and thereafter permanently delete
or otherwise destroy the Eligible Employee’s personal copy. 
 All pay and other benefits (except Plan severance pay and
severance benefits) payable to an Eligible Employee as of his/her Severance Date according to the established policies, plans, and procedures of the Employer shall be paid in accordance with the terms of those established policies, plans and
procedures. In addition, any benefit continuation or conversion rights which an Eligible Employee has as of his/her Severance Date according to the established policies, plans, and procedures of the Employer shall be made available to him/her.

 12.2. Code Section 409A Compliance. It is the Company’s intent that amounts paid under this Plan shall not
constitute “deferred compensation” as that term is defined under Code Section 409A and the regulations promulgated thereunder because the amounts paid under this Plan are structured to comply with the “short-term deferral”
exception to Code Section 409A. However, if any amount paid under this Plan is determined to be “deferred compensation” within the meaning of Code Section 409A and compliance with one or more of the provisions of this Plan causes
or results in a violation of Code Section 409A, then such provision shall be interpreted or reformed in the manner necessary to achieve compliance with Code Section 409A, including but not limited to, the imposition of a six (6) month
delay in payment to any “specified employee” (as defined in Code Section 409A) following such specified employee’s date of termination which entitles him/her to a payment under this Plan. All payments to be made upon a
termination of employment under this Plan may only be made upon a “separation from service” under Code Section 409A. In no event may the Eligible Employee, directly or indirectly, designate the calendar year of a payment. 

12.3. Representations Contrary To The Plan. No employee, officer, or director of an Employer has the authority to alter, vary, or
modify the terms of the Plan except by means of an authorized written amendment to the Plan. No verbal or written representations contrary to the terms of the Plan and its written amendments shall be binding upon the Plan, the Plan Administrator, or
an Employer. 
 12.4. No Employment Rights. This Plan shall not confer employment rights upon any person. No person shall
be entitled, by virtue of the Plan, to remain in the employ of an Employer and nothing in the Plan shall restrict the right of an Employer to terminate the employment of any Eligible Employee or other person at any time. 

  
 15 

 12.5. Plan Funding. No Eligible Employee shall acquire by reason of the Plan any
right in or title to any assets, funds, or property of the Employer. Any severance pay, which becomes payable under the Plan is an unfunded obligation and shall be paid from the general assets of the Company. No employee, officer, director or agent
of the Employer personally guarantees in any manner the payment of Plan severance pay and severance benefits. 
 12.6.
Applicable Law. This Plan shall be governed and construed in accordance with ERISA and in the event that any reference shall be made to State law, the laws of the State of Delaware shall apply, without regard to its conflicts of law
provisions. 
 12.7. Severability. If any provision of the Plan is found, held or deemed by a court of competent
jurisdiction to be void, unlawful or unenforceable under any applicable statute or other controlling law, the remainder of the Plan shall continue in full force and effect. 
 12.8. Recovery Of Payments Made By Mistake. An Eligible Employee shall be required to return to the Company any severance pay payment and any severance benefits payment, or portion thereof, made by
a mistake, including but not limited to, any mistake of fact or law. 
  

			
	PROTHENA BIOSCIENCES INC
		
	By:	 	/s/ Dale B. Schenk
	Its:	 	Chief Executive Officer

 __ 

  
 16 

 PROTHENA BIOSCIENCES INC 

SEVERANCE PLAN 
 ATTACHMENT A 
 For purposes of this Plan, “Employer” means
Prothena Biosciences Inc and each of the following Affiliates to the extent each remains an Affiliate (including wholly-owned subsidiaries of these Affiliates): 
 1. 
 2. 
 3.

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