Form of Aplindore Contingent Value Rights Agreement



 Exhibit 10.2 
 Form of Aplindore CVR Agreement 
 CONTINGENT VALUE RIGHTS AGREEMENT 
 THIS CONTINGENT VALUE RIGHTS AGREEMENT, dated as of [ — ], 2009 (this “Agreement”, is
entered into by and among Ligand Pharmaceuticals Incorporated, a Delaware corporation (“Buyer”), Neurogen Corporation, a Delaware corporation (“Target”), and [ — ],
a [ — ], as Rights Agent (the “Rights Agent”) and as initial Aplindore CVR Registrar (as defined herein). 
 Preamble 
 Buyer, Neon Signal, LLC, a Delaware limited liability company and wholly-owned subsidiary
of Buyer (“Sub”), and Target have entered into an Agreement and Plan of Merger dated as of August 23, 2009 (the “Merger Agreement”), pursuant to which Sub will merge with and into Target (the
“Merger”), with Target surviving the Merger as a subsidiary of Buyer. 
 Pursuant to the Merger Agreement, Buyer
agreed to create and issue to Target’s stockholders of record immediately before the effective time of the Merger, contingent value rights as hereinafter described. 
 The parties have done all things necessary to make the contingent value rights, when issued pursuant to the Merger Agreement and hereunder, the valid obligations of Buyer and to make this Agreement a valid and binding
agreement of Buyer, in accordance with its terms. 
 NOW, THEREFORE, for and in consideration of the premises and the consummation of the
transactions referred to above, it is mutually covenanted and agreed, for the equal and proportionate benefit of all Holders (as hereinafter defined), as follows: 
 ARTICLE I 
 DEFINITIONS 
 Section 1.1. Definitions. 
 (a)
For all purposes of this Agreement, except as otherwise expressly provided or unless the context otherwise requires: 
 (i) the terms
defined in this Article have the meanings assigned to them in this Article, and include the plural as well as the singular; 
 (ii) all
accounting terms used herein and not expressly defined herein shall have the meanings assigned to such terms in accordance with United States generally accepted accounting principles, as in effect on the date hereof; 
 (iii) the words “herein,” “hereof” and “hereunder” and other words of similar import refer to this Agreement as a whole
and not to any particular Article, Section or other subdivision; 
 (iv) unless the context otherwise requires, words describing the
singular number shall include the plural and vice versa, words denoting any gender shall include all genders and words denoting natural Persons shall include corporations, partnerships and other Persons and vice versa; and 







 (v) all references to “including” shall be deemed to mean including without limitation.

 (b) Capitalized terms used but not otherwise defined herein shall have the meanings ascribed thereto in the Merger Agreement. The
following terms shall have the meanings ascribed to them as follows: 
 “Achievement Certificate” has the meaning set forth
in Section 2.4(a). 
 “Aplindore Expense Reserve Balance” means the balance, if any, as of the CVR Outside Date of
funds not paid or payable from the Expense Reserve Amount received by Buyer as provided in Section 5.15(a) of the Merger Agreement. 
 “Aplindore CVR Payment Amount” means an amount equal to (x) the aggregate cash proceeds and/or (to the extent such shares of stock received are listed for trading on a U.S. national securities exchange) shares of stock
received by Buyer, or any of its subsidiaries, after the effective time of the Merger and before the CVR Outside Date, from any purchaser (other than Buyer) of all or substantially all of the assets and property of the Aplindore Program, with
respect to a purchase thereof which closed or closes on or before the CVR Outside Date, plus (y) any Aplindore Expense Reserve Balance, less (i) any costs and expenses reasonably incurred by the Buyer, or any of its subsidiaries, in
connection with the sale of all or substantially all of the assets and property of the Aplindore Program (including commissions and amounts paid to the Consulting Committee as contemplated by Section 5.15(c) of the Merger Agreement) and
(ii) any amounts previously paid to the Holders pursuant to the Aplindore CVRs. For the avoidance of doubt, any amounts deducted from Net Cash Amount as accounts payable relating to the Aplindore Program and any amounts paid by Buyer from the
Expense Reserve Amount shall not be considered “costs and expenses” incurred by Buyer hereunder. 
 “Aplindore CVR Payment
Date” means the date (if any and if ever) that an Aplindore CVR Payment Amount is payable by Buyer to the Holders, which date shall be established pursuant to Section 2.4. 
 “Aplindore CVR Payment Event” means the receipt by Buyer of cash proceeds and/or (to the extent such shares of stock received are listed
for trading on a U.S. national securities exchange) shares of stock of any purchaser (other than Buyer) from the sale of all or substantially all of the assets and property of the Aplindore Program. 
 “Aplindore CVR Register” has the meaning set forth in Section 2.3(b). 
 “Aplindore CVR Registrar” has the meaning set forth in Section 2.3(b). 
 “Aplindore CVRs” means the Aplindore Contingent Value Rights issued by Buyer pursuant to the Merger Agreement and this Agreement.

 “Aplindore Sale” means the sale of all or substantially all of the assets and property of the Aplindore Program to a
Person other than Buyer. 
  

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 “Board of Directors” means the board of directors of Buyer. 
 “Board Resolution” means a copy of a resolution certified by the secretary or an assistant secretary of Buyer to have been duly adopted
by the Board of Directors and to be in full force and effect on the date of such certification, and delivered to the Rights Agent. 
 “Business Day” means any day other than a Saturday, Sunday or a day on which banking institutions in New York, New York are authorized or obligated by law or executive order to remain closed. 
 “CVR Outside Date” means [insert date that is six months from the Effective Date]. 
 “Holder” means a Person in whose name an Aplindore CVR is registered in the Aplindore CVR Register. 
 “Non-Achievement Certificate” has the meaning set forth in Section 2.4(b). 
 “Notice of Objection” has the meaning set forth in Section 2.4(d). 
 “Objection Period” has the meaning set forth in Section 2.4(d). 
 “Officer’s Certificate” means a certificate signed by the chief executive officer, president, chief financial officer, any vice
president, the controller, the treasurer or the secretary, in each case, of Buyer, in his or her capacity as such an officer, and delivered to the Rights Agent. 
 “Permitted Transfer” means: (i) the transfer of any or all of the Aplindore CVRs (upon the death of the Holder) by will or intestacy; (ii) transfer by instrument to an inter vivos or
testamentary trust in which the Aplindore CVRs are to be passed to beneficiaries upon the death of the trustee; (iii) transfers made pursuant to a court order of a court of competent jurisdiction (such as in connection with divorce, bankruptcy
or liquidation); (iv) if the Holder is a partnership or limited liability company, a distribution by the transferring partnership or limited liability company to its partners or members, as applicable; (v) a transfer made by operation of
law (including a consolidation or merger) or in connection with the dissolution, liquidation or termination of any corporation, limited liability company, partnership or other entity; (vi) a transfer from a participant’s account in a
tax-qualified employee benefit plan to the participant or to such participant’s account in a different tax-qualified employee benefit plan or to a tax-qualified individual retirement account for the benefit of such participant; or (vii) a
transfer from a participant in a tax-qualified employee benefit plan, who received the Aplindore CVRs from such participant’s account in such tax-qualified employee benefit plan, to such participant’s account in a different tax-qualified
employee benefit plan or to a tax-qualified individual retirement account for the benefit of such participant. 
 “Person”
means any natural person, corporation, partnership, limited liability company, trust, estate, other firm or entity, or governmental body. 
 “Rights Agent” means the Rights Agent named in the first paragraph of this Agreement, until a successor Rights Agent shall have become such pursuant to the applicable provisions of this Agreement, and thereafter
“Rights Agent” shall mean such successor Rights Agent. 
 “Rights Agent Fee” means the agreed-upon fee of the
Rights Agent to act in such capacity pursuant to the terms of this Agreement. 
 “Surviving Person” has the meaning set
forth in Section 6.1(a)(i). 
  

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 ARTICLE II 
 CONTINGENT VALUE RIGHTS 
 Section 2.1. Issuance of Aplindore CVRs; Appointment of Rights
Agent. 
 (a) The Aplindore CVRs shall be issued pursuant to the Merger Agreement at the time and in the manner set forth in the Merger
Agreement. 
 (b) Buyer hereby appoints [ — ] as the Rights Agent to act as rights agent for Buyer in
accordance with the instructions hereinafter set forth in this Agreement, and the Rights Agent hereby accepts such appointment. 
 Section 2.2. Nontransferable. 
 The Aplindore CVRs shall not be sold, assigned, transferred, pledged, encumbered or in
any other manner transferred or disposed of, in whole or in part, other than through a Permitted Transfer. 
 Section 2.3. No
Certificate; Registration; Registration of Transfer; Change of Address. 
 (a) The Aplindore CVRs shall not be evidenced by a certificate
or other instrument. 
 (b) The Rights Agent shall keep a register (the “Aplindore CVR Register”) for the
registration of Aplindore CVRs. The Rights Agent is hereby initially appointed “Aplindore CVR Registrar” for the purpose of registering Aplindore CVRs and transfers of Aplindore CVRs as herein provided. Upon any change
to the identity of the Rights Agent, the successor Rights Agent shall automatically also become the successor Aplindore CVR Registrar. 
 (c)
Subject to the restriction on transferability set forth in Section 2.2, every request made to transfer an Aplindore CVR must be in writing and accompanied by a written instrument or instruments of transfer and any other requested documentation
in a form reasonably satisfactory to Buyer and the Aplindore CVR Registrar, duly executed by the registered Holder or Holders thereof or by the duly appointed legal representative thereof or by a duly authorized attorney, such signature to be
guaranteed by a participant in a recognized Signature Guarantee Medallion Program. A request for a transfer of an Aplindore CVR shall be accompanied by such documentation establishing that the transfer is a Permitted Transfer as may be reasonably
requested by Buyer and/or the Aplindore CVR Registrar (including opinions of counsel), if appropriate. Upon receipt of such written request and materials, the Aplindore CVR Registrar shall, subject to its reasonable determination that the transfer
instrument is in proper form and the transfer otherwise complies with the other terms and conditions herein, register the transfer of the Aplindore CVRs in the Aplindore CVR Register. All duly transferred Aplindore CVRs registered in the
Aplindore CVR Register shall be the valid obligations of Buyer, evidencing the same right and shall entitle the transferee to the same benefits and rights under this Agreement, as those previously held by the transferor. No transfer of an Aplindore
CVR shall be valid until registered in the Aplindore CVR Register, and any transfer not duly registered in the Aplindore CVR Register will be void ab initio. Any transfer or assignment of the Aplindore CVRs shall be without charge (other than the
cost of any transfer tax which shall be the responsibility of the transferor) to the Holder. 
  

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 (d) A Holder may make a written request to the Aplindore CVR Registrar to change such Holder’s
address of record in the Aplindore CVR Register. The written request must be duly executed by the Holder. Upon receipt of such written notice, the Aplindore CVR Registrar shall promptly record the change of address in the Aplindore CVR Register.

 Section 2.4. Payment Procedures. 
 (a) Promptly following the occurrence of any Aplindore CVR Payment Event, but in no event later than five Business Days after the occurrence of such Aplindore CVR Payment Event, Buyer shall deliver to the Rights Agent
a certificate (the “Achievement Certificate”), certifying that the Holders are entitled to receive such Aplindore CVR Payment Amount. No transaction described in Section 6.1(a) hereof shall give the
Holders the right to receive an Aplindore CVR Payment Amount. 
 (b) If the Aplindore Sale has not occurred on or before the CVR Outside
Date, then, within five Business Days after the CVR Outside Date, Buyer shall deliver to the Rights Agent a certificate (the “Non-Achievement Certificate”), stating that the Aplindore Sale has not occurred on or before the
CVR Outside Date and no Aplindore CVR Payment Event can occur. 
 (c) Except as otherwise requested by any Holder, the Rights Agent shall
promptly (and in no event later than five Business Days after receipt thereof) send each Holder a copy of any Achievement Certificate or Non-Achievement Certificate at its registered address. 
 (d) Upon demand by any Holder or Holders of at least 20% in the aggregate of the outstanding Aplindore CVRs within 45 calendar days after
distribution by the Rights Agent of a Non-Achievement Certificate (the “Objection Period”), the Rights Agent shall deliver a written notice to Buyer prepared by such Holder or Holders specifying that such Holder or Holders
object to the determination of Buyer that the Aplindore Sale did not timely occur (a “Notice of Objection”) and stating the reason upon which such Holder or Holders have determined that the Aplindore Sale occurred on or
before the CVR Outside Date. Any dispute arising from a Notice of Objection shall be resolved in accordance with the procedure set forth in Section 7.12, which decision shall be binding on the parties hereto and every Holder (including Holders
not participating therein). 
 (e) If a Notice of Objection has not been delivered to Buyer within the Objection Period, then the Holders
shall have no right to receive any Aplindore CVR Payment Amount, and Buyer and the Rights Agent shall have no further obligations with respect to the Aplindore CVR Payment Amount(s). 
 (f) If (i) Buyer delivers an Achievement Certificate to the Rights Agent or (ii) an Aplindore CVR Payment Amount is determined to be payable
pursuant to Section 2.4(d) above or (iii) an Aplindore Expense Reserve Balance exists at the CVR Outside Date, then Buyer shall establish an Aplindore CVR Payment Date that is within 15 calendar days after the date of the Achievement
Certificate or the date of final determination pursuant to Section 2.4(d) above, as applicable. At least five Business Days before such Aplindore CVR Payment Date, Buyer shall cause the Aplindore CVR Payment Amount to be delivered to the Rights
Agent, who will in turn, on the Aplindore CVR Payment Date, distribute the Aplindore CVR Payment Amount to the Holders (each Holder being 

  

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entitled to receive its pro rata share of the Aplindore CVR Payment Amount based on the number of Aplindore CVRs held (as of the date of the
Achievement Certificate or the date of final determination pursuant to Section 2.4(d) above, as applicable) by such Holder as reflected on the Aplindore CVR Register) (i) by check mailed to the address of each such respective Holder as
reflected in the Aplindore CVR Register as of the close of business on the last Business Day before such Aplindore CVR Payment Date, or, (ii) with respect to any Holder that is due payment pursuant to this Agreement in excess of $1,000,000 who
has provided the Rights Agent with wire transfer instructions, by wire transfer of immediately available funds to such account. 
 (g) Buyer
shall be entitled to deduct and withhold, or cause to be deducted or withheld, from each Aplindore CVR Payment Amount otherwise payable pursuant to this Agreement, such amounts as Buyer or the applicable subsidiary of Buyer is required to deduct and
withhold with respect to the making of such payment under the Internal Revenue Code, or any provision of state, local or foreign tax law. To the extent that amounts are so withheld or paid over to or deposited with the relevant governmental entity,
such withheld amounts shall be treated for all purposes of this Agreement as having been paid to the Holder in respect of which such deduction and withholding was made. 
 (h) Subject to prior execution and delivery by the Rights Agent of a reasonable and customary confidentiality/nonuse agreement, Buyer shall promptly furnish to the Rights Agent all information and documentation in
connection with this Agreement and the Aplindore CVRs that the Rights Agent or any Holder or Holders of at least 20% in the aggregate of the outstanding Aplindore CVRs may reasonably request in connection with the determination of whether an
Aplindore CVR Payment Event has occurred. Subject to prior execution and delivery by the applicable Holders of a reasonable and customary confidentiality/nonuse agreement, the Rights Agent shall forward any information and documentation it receives
to the Holders who request such information. 
 Section 2.5. No Voting, Dividends or Interest; No Equity or Ownership Interest in
Buyer. 
 (a) The Aplindore CVRs shall not have any voting or dividend rights, and interest shall not accrue on any amounts payable on the
Aplindore CVRs to any Holder. 
 (b) The Aplindore CVRs shall not represent any equity or ownership interest in Buyer or in any constituent
company to the Merger. 
 Section 2.6. Sole Discretion and Decision Making Authority; No Fiduciary Duty. 
 (a) (a) Notwithstanding anything else in this Agreement to the contrary, Buyer shall attempt to sell the Aplindore Program for the benefit of the Holders
of the Aplindore CVRs, but shall have sole discretion and decision making authority, which shall be exercised in good faith and with commercial reasonableness, over (a) any continued operation of, development of or investment in the Aplindore
Program and (b) when (if ever) to consummate the sale of all or any portion of the Aplindore Program to any purchaser, and upon what terms and conditions; provided, however, that before the CVR Outside Date Buyer shall not sell
all or any portion of the Aplindore Program for any consideration other than cash or shares of stock listed for trading on a U.S. national securities exchange. If Buyer, after engaging in the efforts described above in this paragraph, is unable
to sell the Aplindore Program at any price by the CVR Outside Date, then Buyer shall deliver to the Rights Agent a certificate of an executive officer of Buyer to that effect on the CVR Outside Date.  
  

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 ARTICLE III 
 THE RIGHTS AGENT 
 Section 3.1. Certain Duties and Responsibilities. 
 (a) The Rights Agent shall not have any liability for any actions taken or not taken in connection with this Agreement, except to the extent of its
willful misconduct, bad faith or gross negligence. No provision of this Agreement shall require the Rights Agent to expend or risk its own funds or otherwise incur any financial liability in the performance of any of its duties hereunder or in the
exercise of any of its rights or powers. 
 (b) Any Holder or Holders of at least 20% in the aggregate of the outstanding Aplindore CVRs may
direct the Rights Agent to act on behalf of the Holders in enforcing any of its or their rights hereunder, including, without limitation, the delivery of any Notice of Objection and negotiation or arbitration pursuant to Section 7.12. The
Rights Agent shall be under no obligation to institute any action, suit or legal proceeding or to take any other action likely to involve material expense unless such Holder or Holders shall furnish the Rights Agent with reasonable security and
indemnity for any costs and expenses which may be incurred. All rights of action under this Agreement may be enforced by the Rights Agent, and any action, suit or proceeding instituted by the Rights Agent shall be brought in its name as Rights
Agent, and any recovery of judgment shall be for the ratable benefit of all the Holders, as their respective rights or interests may appear. 
 Section 3.2. Certain Rights of Rights Agent. 
 The Rights Agent undertakes to perform such duties and only such duties
as are specifically set forth in this Agreement, and no implied covenants or obligations shall be read into this Agreement against the Rights Agent. In addition: 
 (a) the Rights Agent may rely and shall be protected in acting or refraining from acting upon any resolution, certificate, statement, instrument, opinion, report, notice, request, direction, consent, order or other
paper or document believed by it to be genuine and to have been signed or presented by the proper party or parties; 
 (b) whenever the
Rights Agent shall deem it desirable that a matter be proved or established before taking, suffering or omitting any action hereunder, the Rights Agent may, in the absence of willful misconduct, bad faith or gross negligence on its part, rely upon
an Officer’s Certificate; 
 (c) the Rights Agent may engage and consult with counsel of its selection and the written advice of such
counsel or any opinion of counsel shall be full and complete authorization and protection in respect of any action taken, suffered or omitted by it hereunder in good faith and in reliance thereon; 
 (d) in the event of arbitration, the Rights Agent may engage and consult with tax experts, valuation firms and other experts and third parties that it,
in its sole and absolute discretion, deems appropriate or necessary to enable it to discharge its duties hereunder; 
  

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 (e) the permissive rights of the Rights Agent to do things enumerated in this Agreement shall not be
construed as a duty; 
 (f) the Rights Agent shall not be required to give any note or surety in respect of the execution of such powers or
otherwise in respect of the premises; 
 (g) Buyer agrees to indemnify the Rights Agent for, and hold the Rights Agent harmless against, any
loss, liability, claim, demands, suits or expense (in each case pertaining to the Rights Agent’s own account only) arising out of or in connection with the Rights Agent’s duties under this Agreement, including the costs and expenses of
defending the Rights Agent against any claims, charges, demands, suits or loss, unless such loss shall have been determined by a court of competent jurisdiction to be a result of the Rights Agent’s willful misconduct, bad faith or gross
negligence; and 
 (h) Buyer agrees (i) to pay the fees and expenses of the Rights Agent in connection with this Agreement, as set forth
on Schedule 1 hereto, and (ii) to reimburse the Rights Agent for all taxes and governmental charges, reasonable expenses and other charges of any kind and nature incurred by the Rights Agent in the execution of this Agreement (other than taxes
measured by the Rights Agent’s net income). The Rights Agent shall also be entitled to reimbursement from Buyer for all reasonable and necessary out-of-pocket expenses (including reasonable fees and expenses of the Rights Agent’s counsel
and agent) paid or incurred by it in connection with the administration by the Rights Agent of its duties hereunder. An invoice for the Rights Agent Fee will be rendered a reasonable time before, and paid on, the effective date of the applicable
transaction. An invoice for any out-of-pocket expenses and per item fees realized will be rendered and payable within 30 calendar days after receipt by Buyer. Buyer agrees to pay to Rights Agent any amounts, including fees and expenses, payable in
favor of the Rights Agent in connection with any dispute, resolution or arbitration arising under or in connection with the Agreement; provided, however, that in the event of a resolution in favor of Buyer, any amounts, including fees and expenses,
payable by Buyer in favor of the Rights Agent or payable in favor of Buyer related to such dispute, resolution or arbitration shall be offset against the Aplindore CVR Payment Amount, if any, or any payment to be made thereafter under any of the
other CVR Agreements. 
 Section 3.3. Resignation and Removal; Appointment of Successor. 
 (a) The Rights Agent may resign at any time by giving written notice thereof to Buyer specifying a date when such resignation shall take effect, which
notice shall be sent at least 30 days before the date so specified. 
 (b) If the Rights Agent shall resign, be removed or become
incapable of acting, Buyer, by way of a Board Resolution, shall promptly appoint a qualified successor Rights Agent who may (but need not) be a Holder but shall not be an officer of Buyer. The successor Rights Agent so appointed shall, forthwith
upon its acceptance of such appointment in accordance with this Section 3.3(b), become the successor Rights Agent. 
 (c) Buyer shall
give notice of each resignation and each removal of a Rights Agent and each appointment of a successor Rights Agent by mailing written notice of such event by first-class mail, postage prepaid, to the Holders as their names and addresses appear in
the Aplindore CVR Register. Each notice shall include the name and address of the successor Rights Agent. If Buyer fails to send such notice within ten days after acceptance of appointment by a successor Rights Agent, the successor Rights Agent
shall cause such notice to be mailed at the expense of Buyer. 
  

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 Section 3.4. Acceptance of Appointment by Successor. 
 Every successor Rights Agent appointed hereunder shall execute, acknowledge and deliver to Buyer and to the retiring Rights Agent an instrument accepting
such appointment and a counterpart of this Agreement, and thereupon such successor Rights Agent, without any further act, deed or conveyance, shall become vested with all the rights, powers, trusts and duties of the retiring Rights Agent; provided,
that upon the request of Buyer or the successor Rights Agent, such retiring Rights Agent shall execute and deliver an instrument transferring to such successor Rights Agent all the rights, powers and trusts of the retiring Rights Agent and shall
cooperate in the transfer of all relevant data, including the Aplindore CVR Register, to the successor Rights Agent. 
 ARTICLE IV 

 COVENANTS 
 Section 4.1. List of Holders. 
 Buyer shall furnish or cause to be furnished to the Rights Agent in such form as Buyer
receives from its transfer agent (or other agent performing similar services for Buyer), the names, addresses and shareholdings of the Holders, within five Business Days after the effective time of the Merger. 
 Section 4.2. Payment of Aplindore CVR Payment Amount. 
 Buyer shall duly and promptly pay each Aplindore CVR Payment Amount, if any, in immediately available funds, to the Rights Agent to be distributed to the Holders in the manner provided for in Section 2.4 and in
accordance with the terms of this Agreement. 
 Section 4.3. Section 4.3 Assignments 
 Buyer shall not, in whole or in part, assign any of its obligations under this Agreement other than in accordance with the terms of Section 6.1
hereof. 
 ARTICLE V 
 AMENDMENTS 
 Section 5.1. Amendments Without Consent of Holders. 
 (a) Without the consent of any Holders or the Rights Agent, Buyer, when authorized by a Board Resolution, at any time and from time to time, may enter
into one or more amendments hereto, for any of the following purposes: 
 (i) to evidence the succession of another Person to Buyer and the
assumption by any such successor of the covenants of Buyer herein in a transaction contemplated by Section 6.1 hereof; or 
  

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 (ii) to evidence the termination of the Aplindore CVR Registrar and the succession of another Person as
a successor Aplindore CVR Registrar and the assumption by any successor of the obligations of the Aplindore CVR Registrar herein. 
 (b)
Without the consent of any Holders, Buyer, when authorized by a Board Resolution, and the Rights Agent, in the Rights Agent’s sole and absolute discretion, at any time and from time to time, may enter into one or more amendments hereto, for any
of the following purposes: 
 (i) to evidence the succession of another Person as a successor Rights Agent and the assumption by any
successor of the covenants and obligations of the Rights Agent herein; 
 (ii) to add to the covenants of Buyer such further covenants,
restrictions, conditions or provisions as the Board of Directors and the Rights Agent shall consider to be for the protection of the Holders; provided, that in each case, such provisions shall not adversely affect the interests of the Holders;

 (iii) to cure any ambiguity, to correct or supplement any provision herein that may be defective or inconsistent with any other provision
herein, or to make any other provisions with respect to matters or questions arising under this Agreement; provided, that in each case, such provisions shall not adversely affect the interests of the Holders; or 
 (iv) to add, eliminate or change any provision of this Agreement unless such addition, elimination or change is adverse to the interests of the Holders.

 (c) Promptly after the execution by Buyer and the Rights Agent of any amendment pursuant to the provisions of this Section 5.1, Buyer
shall mail a notice thereof by first-class mail to each of the Holders at their addresses as they shall appear on the Aplindore CVR Register, setting forth in general terms the substance of such amendment. 
 Section 5.2. Amendments With Consent of Holders. 
 (a) Subject to Section 5.1 (which amendments pursuant to Section 5.1 may be made without the consent of the Holders), with the consent of the Holders of not less than a majority of the outstanding Aplindore
CVRs, whether evidenced in writing or taken at a meeting of the Holders, Buyer, when authorized by a Board Resolution, and the Rights Agent may enter into one or more amendments hereto for the purpose of adding, eliminating or changing any
provisions of this Agreement, even if such addition, elimination or change is in any way adverse to the interests of the Holders. 
 (b)
Promptly after the execution by Buyer and the Rights Agent of any amendment pursuant to the provisions of this Section 5.2, Buyer shall mail a notice thereof by first-class mail to the Holders at their addresses as they shall appear on the
Aplindore CVR Register, setting forth in general terms the substance of such amendment. 
 Section 5.3. Execution of Amendments.

 In executing any amendment permitted by this Article V, the Rights Agent shall be entitled to receive, and shall be fully protected in
relying upon, an opinion of counsel stating that the execution of such amendment is authorized or permitted by this Agreement. The Rights Agent may, but is not obligated to, enter into any such amendment that affects the Rights Agent’s own
rights, privileges, covenants or duties under this Agreement or otherwise. 
  

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 Section 5.4. Effect of Amendments. 
 Upon the execution of any amendment under this Article V, this Agreement shall be modified in accordance therewith, such amendment shall form a part of
this Agreement for all purposes and every Holder shall be bound thereby. 
 ARTICLE VI 
 CONSOLIDATION, MERGER, SALE OR CONVEYANCE 
 Section 6.1. Buyer May Consolidate, Etc. 
 (a) Buyer shall not consolidate with or merge into any other Person or
convey, transfer or lease its properties and assets substantially as an entirety to any Person, unless: 
 (i) the Person formed by such
consolidation or into which Buyer is merged or the Person that acquires by conveyance or transfer, or that leases, the properties and assets of Buyer substantially as an entirety (the “Surviving Person”) shall expressly
assume payment (if and to the extent required hereunder) of amounts on all the Aplindore CVRs and the performance of every duty and covenant of this Agreement on the part of Buyer to be performed or observed; and 
 (ii) Buyer has delivered to the Rights Agent an Officer’s Certificate, stating that such consolidation, merger, conveyance, transfer or lease
complies with this Article VI and that all conditions precedent herein provided for relating to such transaction have been complied with. 
 (b) In the event Buyer conveys, transfers or leases its properties and assets substantially as an entirety in accordance with the terms and conditions of this Section 6.1, Buyer and the Surviving Person shall be jointly and severally
liable for the payment of the Aplindore CVR Payment Amount and the performance of every duty and covenant of this Agreement on the part of the Buyer to be performed or observed. 
 Section 6.2. Successor Substituted. 
 Upon any consolidation of or merger by Buyer with or into any other Person, or any conveyance, transfer or lease of the properties and assets substantially as an entirety to any Person in accordance with Section 6.1, the Surviving
Person shall succeed to, and be substituted for, and may exercise every right and power of, Buyer under this Agreement with the same effect as if the Surviving Person had been named as Buyer herein, and thereafter the predecessor Person shall be
relieved of all obligations and covenants under this Agreement and the Aplindore CVRs. 
 ARTICLE VII 
 OTHER PROVISIONS OF GENERAL APPLICATION 
 Section 7.1. Notices to Rights Agent and Buyer. 
 Any request, demand, authorization, direction, notice, consent, waiver
or other document provided or permitted by this Agreement shall be sufficient for every purpose hereunder if in writing and sent by facsimile transmission, delivered personally, or by 

  

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certified or registered mail (return receipt requested and first-class postage prepaid) or sent by a nationally recognized overnight courier (with proof of
service), addressed as follows, and shall be deemed to have been given upon receipt: 
 (a) if to the Rights Agent, addressed to it at [
— ], facsimile at [ — ], or at any other address previously furnished in writing to the Holders and Buyer by the Rights Agent in accordance with this Section 7.1; or

 (b) if to Buyer, addressed to it at 10275 Science Center Drive, San Diego, California 92121, facsimile at (858) 550-7272, or at any
other address previously furnished in writing to the Rights Agent and the Holders by Buyer in accordance with this Section 7.1. 
 Section 7.2. Notice to Holders. 
 Where this Agreement provides for notice to Holders, such notice shall be sufficiently
given (unless otherwise herein expressly provided) if in writing and mailed, first-class postage prepaid, to each Holder affected by such event, at his, her or its address as it appears in the Aplindore CVR Register, not later than the latest date,
and not earlier than the earliest date, prescribed for the giving of such notice. In any case where notice to Holders is given by mail, neither the failure to mail such notice, nor any defect in any notice so mailed, to any particular Holder shall
affect the sufficiency of such notice with respect to other Holders. 
 Section 7.3. Effect of Headings. 
 The Article and Section headings herein are for convenience only and shall not affect the construction hereof. 
 Section 7.4. Successors and Assigns. 
 All covenants and agreements in this Agreement by Buyer shall bind its successors and assigns, whether so expressed or not. 
 Section 7.5. Benefits of Agreement. 
 Nothing in this Agreement, express or implied, shall give to any Person (other
than the parties hereto, the Holders and their permitted successors and assigns hereunder) any benefit or any legal or equitable right, remedy or claim under this Agreement or under any covenant or provision herein contained, all such covenants and
provisions being for the sole benefit of the parties hereto, the Holders and their permitted successors and assigns. The Holders shall have no rights or remedies hereunder except as expressly set forth herein. 
 Section 7.6. Governing Law. 
 This Agreement and the Aplindore CVRs shall be governed by and construed in accordance with the laws of the State of Delaware without regards to its rules of conflicts of laws. 
 Section 7.7. Legal Holidays. 
 In
the event that an Aplindore CVR Payment Date shall not be a Business Day, then, notwithstanding any provision of this Agreement to the contrary, any payment required to be made in respect of the Aplindore CVRs on such date need not be made on such
date, but may be made on the next succeeding Business Day with the same force and effect as if made on the Aplindore CVR Payment Date. 
  

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 Section 7.8. Severability Clause. 
 In case any one or more of the provisions contained in this Agreement shall for any reason be held to be invalid, illegal or unenforceable in any respect,
such invalidity, illegality or unenforceability shall not affect any other provisions of this Agreement, but this Agreement shall be construed as if such invalid or illegal or unenforceable provision had never been contained herein. Upon such
determination that any term or other provision is invalid, illegal or unenforceable, the court or other tribunal making such determination is authorized and instructed to modify this Agreement so as to effect the original intent of the parties as
closely as possible so that the transactions and agreements contemplated herein are consummated as originally contemplated to the fullest extent possible. 
 Section 7.9. Counterparts. 
 This Agreement may be signed in any number of counterparts (which
may be effectively delivered by facsimile or other electronic means), each of which shall be deemed to constitute but one and the same instrument 
 Section 7.10. Termination. 
 This Agreement shall terminate and be of no further force or effect, and the parties hereto
shall have no liability hereunder, upon the earliest to occur of (a) the payment of the last possible Aplindore CVR Payment Amount, (b) in the event that a Notice of Objection is not delivered within the Objection Period, the expiration of
the Objection Period or (c) in the event of the delivery of a Notice of Objection, either (i) the final determination in accordance with this Agreement that the Aplindore Sale was not closed on or before the CVR Outside Date or
(ii) the fulfillment of the last possible payment or other obligation required pursuant to a final determination made in accordance with this Agreement. 
 Section 7.11. Entire Agreement. 
 This Agreement and the Merger Agreement represent the entire
understanding of the parties hereto with reference to the Aplindore CVRs and this Agreement supersedes any and all other oral or written agreements made with respect to the Aplindore CVRs, except for the Merger Agreement. If and to the extent that
any provision of this Agreement is inconsistent or conflicts with the Merger Agreement, this Agreement shall govern and be controlling. 
 Section 7.12. Negotiation; Arbitration. 
 (a) Before any arbitration pursuant to Section 7.12(b), Buyer, the Rights
Agent and, if available, any Holder or Holders of at least 20% in the aggregate of the outstanding Aplindore CVRs shall negotiate in good faith for a period of 30 days to resolve any controversy or claim arising out of or relating to this Agreement
or the breach thereof. 
  

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 (b) After expiration of the 30-day period contemplated by Section 7.12(a), such controversy or
claim, including any claims for breach of this Agreement, shall be settled by arbitration administered by the American Arbitration Association under its Commercial Arbitration Rules, and judgment on the award rendered by the arbitrators may be
entered in any court having jurisdiction thereof. Buyer, the Rights Agent and/or any Holder or Holders of at least 20% in the aggregate of the outstanding Aplindore CVRs may initiate an arbitration for any matter relating to this Agreement. However,
in the event of a dispute arising from the delivery of a Notice of Objection, the sole matter to be settled by arbitration shall be whether an Aplindore Sale was closed on or before the CVR Outside Date. The number of arbitrators shall be three.
Within 15 days after the commencement of arbitration, each party shall select one person to act as arbitrator, and the two selected shall select a third arbitrator within 15 days of their appointment. If the arbitrators selected by the parties are
unable or fail to agree upon the third arbitrator, the third arbitrator shall be selected by the American Arbitration Association. The place of the arbitration shall be San Diego, California. The arbitrators shall be lawyers or retired judges with
experience in the life sciences industry and with mergers and acquisitions. Except as may be required by law, neither a party nor an arbitrator may disclose the existence, content or results of any arbitration hereunder without the prior written
consent of both parties (provided that the Rights Agent may disclose to the Holders any such information without the consent of Buyer). Any award payable in favor of the Holders or the Rights Agent as a result of arbitration shall be distributed to
the Holders on a pro rata basis, based on the number of Aplindore CVRs held by each Holder. Buyer shall pay all fees and expenses of the arbitration forum, including the costs and expenses billed by the arbitrators in connection with the performance
of their duties described herein; provided, however, that if the arbitrator rules in favor of Buyer, the Arbitrator’s fees and expenses shall be offset against the current or any future Aplindore CVR Payment Amount, if any, or any payment to be
made thereafter under any of the other CVR Agreements. Each party shall be responsible for its own attorney fees, expenses and costs of investigation. 
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 IN WITNESS WHEREOF, each of the parties has caused this Agreement to be executed on its behalf by
its duly authorized officers as of the day and year first above written. 
  

			
	LIGAND PHARMACEUTICALS INCORPORATED
		
	By:	 	  

	Name:	 	  

	Title:	 	  

	
	NEUROGEN CORPORATION
		
	By:	 	  

	Name:	 	  

	Title:	 	  

	
	[RIGHTS AGENT]
		
	By:	 	  

	Name:	 	  

	Title:	 	  



  

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