8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 22, 2005

NEKTAR THERAPEUTICS

(Exact name of Registrant as specified in its charter)

Delaware	0-24006	94-3134940
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

150 Industrial Road

San Carlos, California 94070

(Address of principal executive offices and Zip Code)

Registrant’s telephone number, including area code: (650) 631-3100

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement.

On September 28, 2005, we completed the sale of $315 million aggregate principal amount of our 3.25% convertible subordinated notes due 2012 (the “Notes”), pursuant to the terms of a Purchase Agreement, dated as of September 22, 2005 (the “Purchase Agreement”) among us and the initial purchasers named therein (the “Initial Purchasers”). Pursuant to the Purchase Agreement, the Initial Purchasers exercised their option to purchase an additional $40 million principal amount of such Notes for an aggregate principal amount of $315 million.

The Notes bear interest at a rate of 3.25% per annum and will be convertible into shares of our common stock at an initial conversion rate of 46.4727 shares per $1,000 principal amount of Notes (subject to adjustment in certain circumstances), which is equivalent to an initial conversion price of approximately $21.52 per share. If a holder of the notes elects to convert notes in connection with certain fundamental changes to our company, such holder may also be entitled to receive a make-whole premium upon conversion in certain circumstances.

The Notes are subordinated to all of our present and future senior debt.

Beginning on September 28, 2008 we may redeem the notes in whole or in part at any time at a redemption price equal to 100% of the principal amount of the notes to be redeemed plus accrued and unpaid interest, if any, to but not including the redemption date if the closing price of our common stock as exceeded 150% of the conversion price of the Notes for at least 20 trading days in any consecutive 30-day trading period ending on the trading day before the date of mailing of the provisional redemption notice.

Pursuant to a Registration Rights Agreement dated as of September 28, 2005 by and between us and the Initial Purchasers, we have agreed to file a shelf registration statement with respect to the resale of the Notes and the common stock issuable upon conversion thereof. In the event we fail to comply with our obligations under the Registration Rights Agreement, we will pay additional interest on the Notes.

The Notes were issued under an indenture between us and J.P. Morgan Trust Company, National Association, as trustee.

We have agreed with a limited number of holders of our outstanding convertible noted due 2007 to repurchase approximately $71 million in aggregate principal amount of such notes. We are using a portion of the proceeds from the sale of the Notes to complete these repurchases.

Item 2.03 Creation of a Direct Financial Obligation.

The information set forth in Item 1.01 is hereby incorporated into Item 2.03 by reference.

Item 3.02 Unregistered Sales of Equity Securities.

The information provided in response to Item 1.01 is hereby incorporated by reference into this Item 3.02.

The company sold the Notes to the Initial Purchasers under an exemption from registration pursuant to Section 4(2) of the Securities Act of 1933 (the “Securities Act”). The Notes were offered and sold only to qualified institutional buyers pursuant to Rule 144A under the Securities Act. Both the exemption under Section 4(2) of the Securities Act for the initial sale of the Notes and the Rule 144A exemption for resale are based upon the representations of the Initial Purchasers in the Purchase Agreement that, among other things, the Initial Purchasers would offer the Notes for resale in the United States solely to qualified institutional buyers under the Securities Act, and in compliance with the other provisions of Rule 144A.

The Notes were offered by the Initial Purchasers as a price of 100.0% of the principal amount of the Notes. The aggregate discount provided to the Initial Purchasers was $8,977,500. Our expenses related to the offer and sale of the Notes are expected to be approximately $325,000.

Item 7.01. Other Events and Required FD Disclosure

On September 27, 2005, Nektar Therapeutics announced that initial purchasers have exercised their option to purchase an additional $40 million of Nektar’s 3.25% convertible subordinated notes due in 2012 pursuant to a purchase agreement dated September 22, 2005. This purchase increased the aggregate principal amount of 3.25% convertible subordinated notes sold in the offering to $315 million. The offering of the notes was made to qualified institutional buyers under Rule 144A of the Securities Act of 1933, as amended. The offering closed on September 28, 2005.

Nektar’s press release, dated September 27, 2005, titled “Nektar Announces Exercise of Option to Purchase $40 Million of Convertible Subordinated Notes” is attached hereto as Exhibit 99.1.

Item 9.01. Financial Statements and Exhibits.

(c) Exhibits

Exhibit Number	Description
4.1	Indenture dated September 28, 2005 by and between Nektar Therapeutics and J.P. Morgan Trust Company, National Association, including the form of 3.25% Convertible Subordinated Notes due 2012 attached as an exhibit thereto.
4.2	Registration Rights Agreement dated September 28, 2005, by and between Nektar Therapeutics and the Initial Purchasers.
10.1	Purchase Agreement dated September 22, 2005 by and between Nektar Therapeutics and the Initial Purchasers.
99.1	Press Release titled “Nektar Announces Exercise of Option to Purchase $40 million of Convertible Subordinated Notes.”

SIGNATURES

Pursuant to the requirement of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

By:	/s/ Nevan Elam
	Nevan Elam Senior Vice President Corporate Operations and General Counsel
Date:	September 28, 2005

EX-4.1

Exhibit 4.1

INDENTURE

between

NEKTAR THERAPEUTICS,

as Issuer

and

J.P. MORGAN TRUST COMPANY,

NATIONAL ASSOCIATION

as Trustee

3.25% CONVERTIBLE SUBORDINATED NOTES DUE 2012

Dated as of September 28, 2005

TABLE OF CONTENTS

		Page
	ARTICLE I
	DEFINITIONS AND INCORPORATION BY REFERENCE
Section 1.1.	Definitions	1
Section 1.2.	Incorporation by Reference of Trust Indenture Act	11
Section 1.3.	Rules of Construction	12
	ARTICLE II
	THE SECURITIES
Section 2.1.	Title and Terms	12
Section 2.2.	Form of Securities	13
Section 2.3.	Legends.	14
Section 2.4.	Execution, Authentication, Delivery and Dating	18
Section 2.5.	Registrar and Paying Agent	18
Section 2.6.	Paying Agent to Hold Assets in Trust	19
Section 2.7.	General Provisions Relating to Transfer and Exchange	19
Section 2.8.	Book-Entry Provisions for the Global Securities.	20
Section 2.9.	Special Transfer Provisions	21
Section 2.10.	Holder Lists	23
Section 2.11.	Persons Deemed Owners	23
Section 2.12.	Mutilated, Destroyed, Lost or Stolen Securities	23
Section 2.13.	Treasury Securities	24

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		Page
Section 2.14.	Temporary Securities	24
Section 2.15.	Cancellation	24
Section 2.16.	CUSIP Numbers	25
Section 2.17.	Defaulted Interest	25
	ARTICLE III
	SATISFACTION AND DISCHARGE
Section 3.1.	Satisfaction and Discharge of Indenture.	25
Section 3.2.	Deposited Monies to be Held in Trust	26
Section 3.3.	Return of Unclaimed Monies	27
	ARTICLE IV
	DEFAULTS AND REMEDIES
Section 4.1.	Events of Default	27
Section 4.2.	Acceleration of Maturity; Rescission and Annulment	28
Section 4.3.	Other Remedies	29
Section 4.4.	Waiver of Past Defaults	29
Section 4.5.	Control by Majority	30
Section 4.6.	Limitation on Suit	30
Section 4.7.	Unconditional Rights of Holders to Receive Payment and to Convert	31
Section 4.8.	Collection of Indebtedness and Suits for Enforcement by the Trustee	31
Section 4.9.	Trustee May File Proofs of Claim	32
Section 4.10.	Restoration of Rights and Remedies	33

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		Page
Section 4.11.	Rights and Remedies Cumulative	33
Section 4.12.	Delay or Omission Not Waiver	33
Section 4.13.	Application of Money Collected	33
Section 4.14.	Undertaking for Costs	33
Section 4.15.	Waiver of Stay or Extension Laws	34
	ARTICLE V
	THE TRUSTEE
Section 5.1.	Certain Duties and Responsibilities	34
Section 5.2.	Certain Rights of Trustee	36
Section 5.3.	Individual Rights of Trustee	36
Section 5.4.	Money Held in Trust	37
Section 5.5.	Trustee’s Disclaimer	37
Section 5.6.	Notice of Defaults	37
Section 5.7.	Reports by Trustee to Holders	37
Section 5.8.	Compensation and Indemnification	37
Section 5.9.	Replacement of Trustee	38
Section 5.10.	Successor Trustee by Merger, Etc	39
Section 5.11.	Corporate Trustee Required; Eligibility	39
Section 5.12.	Collection of Claims Against the Company	39

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		Page
	ARTICLE VI
	CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE
Section 6.1.	Company May Consolidate, Etc., Only on Certain Terms	39
Section 6.2.	Successor Corporation Substituted	40
	ARTICLE VII
	AMENDMENTS, SUPPLEMENTS AND WAIVERS
Section 7.1.	Without Consent of Holders of Securities	40
Section 7.2.	With Consent of Holders of Securities	41
Section 7.3.	Compliance with Trust Indenture Act	42
Section 7.4.	Revocation of Consents and Effect of Consents or Votes	42
Section 7.5.	Notation on or Exchange of Securities	43
Section 7.6.	Trustee to Sign Amendment, Etc	43
	ARTICLE VIII
	MEETING OF HOLDERS OF SECURITIES
Section 8.1.	Purposes for Which Meetings May Be Called	43
Section 8.2.	Call Notice and Place of Meetings	44
Section 8.3.	Persons Entitled to Vote at Meetings	44
Section 8.4.	Quorum; Action	44
Section 8.5.	Determination of Voting Rights; Conduct and Adjournment of Meetings	45
Section 8.6.	Counting Votes and Recording Action of Meetings	45

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		Page
	ARTICLE IX
	COVENANTS
Section 9.1.	Payment of Principal and Interest	46
Section 9.2.	Maintenance of Offices or Agencies	46
Section 9.3.	Corporate Existence	47
Section 9.4.	Maintenance of Properties	47
Section 9.5.	Payment of Taxes and Other Claims	47
Section 9.6.	Reports	47
Section 9.7.	Compliance Certificate	48
Section 9.8.	Resale of Certain Securities	48
	ARTICLE X
	REDEMPTION OF SECURITIES
Section 10.1.	Redemption	48
Section 10.2.	[Reserved]	48
Section 10.3.	Notice to Trustee	48
Section 10.4.	Selection of Securities to Be Redeemed	49
Section 10.5.	Notice of Redemption	49
Section 10.6.	Effect of Notice of Redemption	50
Section 10.7.	Deposit of Redemption Price	50
Section 10.8.	Securities Redeemed in Part	51

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		Page
	ARTICLE XI
	REPURCHASE AT THE OPTION OF A HOLDER UPON A FUNDAMENTAL CHANGE
Section 11.1.	Repurchase Right	51
Section 11.2.	[Reserved]	51
Section 11.3.	Notices; Method of Exercising Repurchase Right, Etc	51
	ARTICLE XII
	CONVERSION OF SECURITIES
Section 12.1.	Conversion Right and Conversion Rate	54
Section 12.2.	Exercise of Conversion Right	54
Section 12.3.	Fractions of Shares	55
Section 12.4.	Adjustment of Conversion Rate	56
Section 12.5.	Notice of Adjustments of Conversion Rate	65
Section 12.6.	Notice Prior to Certain Actions	65
Section 12.7.	Company to Reserve Common Stock	66
Section 12.8.	Taxes on Conversions	66
Section 12.9.	Covenant as to Common Stock	67
Section 12.10.	Cancellation of Converted Securities	67
Section 12.11.	Effect of Recapitalization, Reclassification, Consolidation, Merger or Sale	67
Section 12.12.	Responsibility of Trustee for Conversion Provisions	68
Section 12.13.	Make-Whole Premium.	69

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		Page
	ARTICLE XIII
	SUBORDINATION
Section 13.1.	Securities Subordinated to Senior Debt	70
Section 13.2.	Subrogation	72
Section 13.3.	Obligation of the Company is Absolute and Unconditional	73
Section 13.4.	Maturity of or Default on Senior Debt	73
Section 13.5.	Payments on Securities Permitted	73
Section 13.6.	Effectuation of Subordination by Trustee	73
Section 13.7.	Knowledge of Trustee	73
Section 13.8.	Trustee’s Relation to Senior Debt	74
Section 13.9.	Rights of Holders of Senior Debt Not Impaired	74
Section 13.10.	Modification of Terms of Senior Debt	74
Section 13.11.	Certain Conversions Not Deemed Payment	75
	ARTICLE XIV
	OTHER PROVISIONS OF GENERAL APPLICATION
Section 14.1.	Trust Indenture Act Controls	75
Section 14.2.	Notices	75
Section 14.3.	Communication by Holders with Other Holders	76
Section 14.4.	Acts of Holders of Securities	76
Section 14.5.	Certificate and Opinion as to Conditions Precedent	77
Section 14.6.	Statements Required in Certificate or Opinion	78
Section 14.7.	Effect of Headings and Table of Contents	78

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		Page
Section 14.8.	Successors and Assigns	78
Section 14.9.	Separability Clause	78
Section 14.10.	Benefits of Indenture	78
Section 14.11.	Governing Law	78
Section 14.12.	Counterparts	79
Section 14.13.	Legal Holidays	79
Section 14.14.	Recourse Against Others	79

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INDENTURE, dated as of September 28, 2005, between NEKTAR THERAPEUTICS, a corporation duly organized and existing under the laws of the State of Delaware, having its principal office at 150 Industrial Road, San Carlos, California 94070 (the “Company”), and J.P. MORGAN TRUST COMPANY, NATIONAL ASSOCIATION, a national banking association, as Trustee (the “Trustee”), having its principal corporate trust office at 600 Travis Street, Suite 1150, Houston, Texas 77002.

RECITALS OF THE COMPANY

The Company has duly authorized the creation of an issue of its 3.25% Convertible Subordinated Notes due 2012 (herein called the “Securities”) of substantially the tenor and amount hereinafter set forth, and to provide therefor the Company has duly authorized the execution and delivery of this Indenture.

All things necessary to make the Securities, when the Securities are executed by the Company and authenticated and delivered hereunder and duly issued by the Company, the valid obligations of the Company, and to make this Indenture a valid agreement of the Company, in accordance with their and its terms, have been done.

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

For and in consideration of the premises and the purchase of the Securities by the Holders thereof, it is mutually covenanted and agreed, for the equal and proportionate benefit of all Holders of the Securities, as follows:

ARTICLE I

DEFINITIONS AND INCORPORATION

BY REFERENCE

Section 1.1. Definitions. For all purposes of this Indenture and the Securities, the following terms are defined as follows:

“Act,” when used with respect to any Holder of a Security, has the meaning specified in Section 14.4(a) hereof.

“Affiliate” of any specified Person means any other Person directly or indirectly controlling or controlled by or under direct or indirect common control with such specified Person. For the purposes of this definition, “control,” when used with respect to any specified Person, means the power to direct the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise; and the terms “controlling” and “controlled” have meanings correlative to the foregoing.

“Applicable Procedures” means, with respect to any transfer or exchange of beneficial ownership interests in a Global Security, the rules and procedures of the Depositary, to the extent applicable to such transfer or exchange.

“Bankruptcy Law” means Title 11 of the U.S. Code or any similar federal or state law for the relief of debtors.

“Board of Directors” means either the board of directors of the Company or any committee of that board empowered to act for it with respect to this Indenture.

“Board Resolution” means a resolution duly adopted by the Board of Directors, a copy of which, certified by the Secretary or an Assistant Secretary of the Company to be in full force and effect on the date of such certification, has been delivered to the Trustee.

“Business Combination” has the meaning specified in Section 12.11 hereof.

“Business Day,” when used with respect to any Place of Payment or Place of Conversion, means each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on which banking institutions in that Place of Payment or Place of Conversion, as the case may be, are authorized or obligated by law to close.

“Change of Control” means the occurrence of any of the following after the original issuance of the Securities:

(1) the acquisition by any person of beneficial ownership, directly or indirectly, through a purchase, merger or other acquisition transaction or series of transactions, of shares of capital stock of the Company entitling such person to exercise 50% or more of the total voting power of all shares of capital stock of the Company entitled to vote generally in elections of directors, other than any such acquisition by the Company, any subsidiary of the Company or any employee benefit plan of the Company; or

(2) any consolidation or merger of the Company with or into any other person, any merger of another person into the Company, or any conveyance, transfer, sale, lease or other disposition of all or substantially all of the properties and assets of the Company to another person, other than (a) any such transaction (x) that does not result in any reclassification, conversion, exchange or cancellation of outstanding shares of capital stock of the Company and (y) pursuant to which holders of capital stock of the Company immediately prior to such transaction have the entitlement to exercise, directly or indirectly, 50% or more of the total voting power of all shares of capital stock of the Company entitled to vote generally in the election of directors of the continuing or surviving person immediately after such transaction or (b) any merger which is effected solely to change the jurisdiction of incorporation of the Company and results in a reclassification, conversion or exchange of outstanding shares of Common Stock solely into shares of common stock of the surviving entity;

provided, however, that a Change of Control shall not be deemed to have occurred if 100% of the consideration for the Common Stock (excluding cash payments for fractional shares and cash payments made in respect of dissenters’ appraisal rights) in the transaction or transactions constituting the Change of Control consists of common stock or American Depositary Shares representing shares of common stock traded on a U.S. national securities exchange or quoted on the Nasdaq National Market, or which will be so traded or quoted when issued or exchanged in

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connection with the Change of Control, and as a result of such transaction or transactions the Securities become convertible solely into such common stock or American Depositary Shares representing shares of common stock; provided that, with respect to an entity organized under the laws of a jurisdiction outside the United States of America, such entity has a worldwide total market capitalization of its equity securities of at least $5.0 billion before giving effect to the consolidation or merger. Beneficial ownership shall be determined in accordance with Rule 13d-3 promulgated by the SEC under the Exchange Act. The term “person” shall include any syndicate or group which would be deemed to be a “person” under Section 13(d)(3) of the Exchange Act.

“Chief Executive Officer” means the chief executive officer of the Company.

“close of business” means 5:00 p.m., New York City time.

“Closing Price” on any Trading Day means, with respect to the Company’s Common Stock, the reported last sale price per share of Common Stock (or if no last sale price is reported, the average of the bid and ask prices per share or, if more than one in either case, the average of the average bid and the average ask prices per share) on such date reported by the Nasdaq National Market or, if the Company’s Common Stock is not quoted on the Nasdaq National Market, as reported by the principal national securities exchange on which the Company’s Common Stock is listed, or if no such prices are available, the Closing Price per share shall be the fair value of a share of Common Stock as reasonably determined by the Board of Directors (which determination shall be conclusive and shall be evidenced by an Officers’ Certificate delivered to the Trustee).

“Common Stock” means any stock of any class of the Company which has no preference in respect of dividends or of amounts payable in the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company and which is not subject to redemption by the Company. However, subject to the provisions of Section 12.11 hereof, shares issuable on conversion of Securities shall include only shares of the class designated as Common Stock, par value $0.0001 per share, of the Company at the date of this Indenture or shares of any class or classes resulting from any reclassification or reclassifications thereof and which have no preference in respect of dividends or of amounts payable in the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company and which are not subject to redemption by the Company, provided that if at any time there shall be more than one such resulting class, the shares of each such class then so issuable shall be substantially in the proportion which the total number of shares of such class resulting from all such reclassifications bears to the total number of shares of all such classes resulting from all such reclassifications.

“Company” means the corporation named as the “Company” in the first paragraph of this instrument until a successor corporation shall have become such pursuant to the applicable provisions of this Indenture, and thereafter “Company” shall mean such successor corporation.

“Company Notice” has the meaning specified in Section 11.3 hereof.

“Company Order” means a written order signed in the name of the Company by an Officer of the Company and delivered to the Trustee.

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“Conversion Agent” means any Person authorized by the Company to convert Securities in accordance with Article XII hereof.

“Conversion Price” means, as of any date of determination, $1,000 divided by the Conversion Rate then in effect.

“Conversion Rate” has the meaning specified in Section 12.1 hereof.

“Corporate Trust Office” means for purposes of presentation or surrender of Securities for payment, registration, transfer, exchange or conversion or for service of notices or demands upon the Company, the office of the Trustee located in The City of New York at which at any particular time its corporate trust business shall be administered (which at the date of this Indenture is located at 4 New York Plaza, 15th Floor, New York, New York 10004), and for all other purposes, the office of the Trustee located in the City of Houston, Texas (which at the date of this Indenture is located at 600 Travis Street, Suite 1150, Houston, Texas 77002).

“corporation” means corporations, limited liability companies, partnerships and trusts.

“Current Market Price” has the meaning set forth in Section 12.4(g).

“Custodian” means any receiver, trustee, assignee, liquidator, sequestrator or similar official under any Bankruptcy Law.

“Default” means an event which is, or after notice or lapse of time or both would be, an Event of Default.

“Default Exception” has the meaning specified in Section 4.1(e) hereof.

“Defaulted Interest” has the meaning specified in Section 2.17 hereof.

“Depositary” means The Depository Trust Company, its nominees and their respective successors.

“Designated Senior Debt” means Senior Debt of the Company which is specifically designated in the instrument, agreement or other document evidencing or governing that Senior Debt as “Designated Senior Debt” for purposes of this Indenture.

“Dollar,” “U.S. Dollar” or “U.S. $” means a dollar or other equivalent unit in such coin or currency of the United States as at the time shall be legal tender for the payment of public and private debts.

“DTC Participants” has the meaning specified in Section 2.8(a) hereof.

“Event of Default” has the meaning specified in Section 4.1 hereof.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Expiration Time” has the meaning specified in Section 12.4(f) hereof.

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“fair market value” has the meaning set forth in Section 12.4(g)(ii) hereof.

“Fundamental Change” means the occurrence of either a Change of Control or a Termination of Trading.

“Fundamental Change Effective Date” means the date on which any Fundamental Change becomes effective.

“Fundamental Change Repurchase Notice” has the meaning specified in Section 11.3(b) hereof.

“Global Security” has the meaning specified in Section 2.2 hereof.

“guarantee” means any obligation, contingent or otherwise, of any Person, directly or indirectly guaranteeing any Indebtedness of any other Person and any obligation, direct or indirect, contingent or otherwise, of such Person:

(1) to purchase or pay (or advance or supply funds for the purchase or payment of) such Indebtedness of such other Person (whether arising by virtue of partnership arrangements, or by agreement to keep-well, to purchase assets, goods, securities or services, to take-or-pay, or maintain financial statement conditions or otherwise); or

(2) entered into for purposes of assuring in any other manner the obligee of such Indebtedness of the payment thereof or to protect such obligee against loss in respect thereof (in whole or in part);

provided, however, that the term “guarantee” will not include endorsements for collection or deposit in the ordinary course of business. The term “guarantee” used as a verb has a corresponding meaning.

“Holder,” when used with respect to any Security, means the Person in whose name the Security is registered in the Register.

“Indebtedness,” when used with respect to any Person, and without duplication means:

(1) all indebtedness, obligations and other liabilities (contingent or otherwise) of such Person for borrowed money (including obligations of the Company in respect of overdrafts, foreign exchange contracts, currency exchange agreements, Interest Rate Protection Agreements, and any loans or advances from banks, whether or not evidenced by notes or similar instruments) or evidenced by bonds, debentures, notes or other instruments for the payment of money, or incurred in connection with the acquisition of any property, services or assets (whether or not the recourse of the lender is to the whole of the assets of such Person or to only a portion thereof), other than any account payable or other accrued current liability or obligation to trade creditors incurred in the ordinary course of business in connection with the obtaining of materials or services;

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(2) all reimbursement obligations and other liabilities (contingent or otherwise) of such Person with respect to letters of credit, bank guarantees, bankers’ acceptances, surety bonds, performance bonds or other guaranty of contractual performance;

(3) all obligations and liabilities (contingent or otherwise) in respect of (a) leases of such Person required, in conformity with generally accepted accounting principles, to be accounted for as capitalized lease obligations on the balance sheet of such Person and (b) any lease or related documents (including a purchase agreement) in connection with the lease of real property which provides that such Person is contractually obligated to purchase or cause a third party to purchase the leased property and thereby guarantee a minimum residual value of the leased property to the landlord and the obligations of such Person under such lease or related document to purchase or to cause a third party to purchase the leased property;

(4) all obligations of such Person (contingent or otherwise) with respect to an interest rate or other swap, cap or collar agreement or other similar instrument or agreement or foreign currency hedge, exchange, purchase or similar instrument or agreement;

(5) all direct or indirect guaranties or similar agreements by such Person in respect of, and obligations or liabilities (contingent or otherwise) of such Person to purchase or otherwise acquire or otherwise assure a creditor against loss in respect of, indebtedness, obligations or liabilities of another Person of the kind described in clauses (1) through (4);

(6) any indebtedness or other obligations described in clauses (1) through (5) secured by any mortgage, pledge, lien or other encumbrance existing on property which is owned or held by such Person, regardless of whether the indebtedness or other obligation secured thereby shall have been assumed by such Person; and

(7) any and all deferrals, renewals, extensions and refundings of, or amendments, modifications or supplements to, any indebtedness, obligation or liability of the kind described in clauses (1) through (6).

“Indenture” means this instrument as originally executed or as it may from time to time be supplemented or amended by one or more indentures supplemental hereto entered into pursuant to the applicable provisions hereof.

“Initial Purchasers” mean Merrill Lynch, Pierce, Fenner & Smith Incorporated, Lehman Brothers Inc., Goldman Sachs & Co., Deutsche Bank Securities Inc., W.R. Hambrecht + Co, LLC, Leerink Swann & Company, SG Cowen & Co., LLC and SunTrust Capital Markets, Inc.

“Interest Payment Date” means each March 28 and September 28.

“Interest Rate Protection Agreement” means, with respect to any Person, any interest rate swap agreement, interest rate cap or collar agreement or other financial agreement or arrangement designed to protect such person against fluctuations in interest rates, as in effect from time to time.

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“Internal Revenue Service” means the United States Internal Revenue Service.

“Liquidated Damages” means all liquidated damages, if any, payable pursuant to Section 3 of the Registration Rights Agreement.

“Make-Whole Premium” has the meaning specified in Section 12.13 hereof.

“Maturity” means the date on which the principal of such Security becomes due and payable as therein or herein provided, whether at the Stated Maturity or by acceleration, conversion, call for redemption, exercise of a Repurchase Right or otherwise.

“Nasdaq National Market” means the National Association of Securities Dealers Automated Quotation National Market or any successor national securities exchange or automated over-the-counter trading market in the United States.

“Officer” of the Company means the Chairman of the Board, the Chief Executive Officer, the President, the Chief Financial Officer, the Treasurer, any Vice President, the Controller, the Comptroller or the Secretary of the Company.

“Officers’ Certificate” means a certificate signed by both (1) the Chairman of the Board, the Chief Executive Officer, the President or a Vice President and (2) so long as not the same as the officer signing pursuant to clause (1), the Chief Financial Officer or the Secretary of the Company, and delivered to the Trustee.

“Opinion of Counsel” means a written opinion of counsel, who may be counsel to the Company (and may include directors or employees of the Company) and which opinion is reasonably acceptable to the Trustee.

“Outstanding,” when used with respect to Securities, means, as of the date of determination, all Securities theretofore authenticated and delivered under this Indenture, except Securities:

(1) previously canceled by the Trustee or delivered to the Trustee for cancellation;

(2) for the payment or redemption of which money in the necessary amount has been previously deposited with the Trustee or any Paying Agent (other than the Company) in trust or set aside and segregated in trust by the Company (if the Company shall act as its own Paying Agent) for the Holders of such Securities, provided that if such Securities are to be redeemed, notice of such redemption has been duly given pursuant to this Indenture; and

(3) which have been paid, in exchange for or in lieu of which other Securities have been authenticated and delivered pursuant to this Indenture, other than any such Securities in respect of which there shall have been presented to the Trustee proof satisfactory to it that such Securities are held by a bona fide purchaser in whose hands such Securities are valid obligations of the Company.

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“Paying Agent” has the meaning specified in Section 2.5 hereof.

“Payment Blockage Notice” has the meaning specified in Section 13.1(d) hereof.

“Person” means any individual, corporation, limited liability company, partnership, joint venture, association, joint-stock company, trust, estate, unincorporated organization or government or any agency or political subdivision thereof.

“Physical Securities” has the meaning specified in Section 2.2 hereof.

“Place of Conversion” means any city in which any Conversion Agent is located.

“Place of Payment” means any city in which any Paying Agent is located.

“Predecessor Security” of any particular Security means every previous Security evidencing all or a portion of the same debt as that evidenced by such particular Security; and, for the purposes of this definition, any Security authenticated and delivered under Section 2.12 hereof in exchange for or in lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen Security.

“Purchase Agreement” means the Purchase Agreement, dated September 22, 2005, among the Company and the Initial Purchasers.

“QIB” means a “qualified institutional buyer” as defined in Rule 144A.

“Record Date” means either a Regular Record Date or a Special Record Date, as the case may be, provided that, for purposes of Section 12.4 hereof, Record Date has the meaning specified in 12.4(g) hereof.

“Redemption” has the meaning specified in Section 10.1 hereof.

“Redemption Date,” when used with respect to any Security to be redeemed, means the dated fixed for such redemption pursuant to this Indenture.

“Redemption Price” has the meaning specified in Section 10.1 hereof.

“Reference Period” has the meaning set forth in Section 12.4(d) hereof.

“Register” has the meaning specified in Section 2.5 hereof.

“Registrar” has the meaning specified in Section 2.5 hereof.

“Registration Rights Agreement” means the Registration Rights Agreement dated as of September 28, 2005, among the Company and the Initial Purchasers.

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“Regular Record Date” for the interest on the Securities (including Liquidated Damages, if any) payable means the March 13 (whether or not a Business Day) next preceding a March 28 Interest Payment Date and the September 13 (whether or not a Business Day) next preceding a September 28 Interest Payment Date.

“Repurchase Date” has the meaning specified in Section 11.1 hereof.

“Repurchase Price” has the meaning specified in Section 11.1 hereof.

“Repurchase Right” has the meaning specified in Section 11.1 hereof.

“Responsible Officer,” when used with respect to the Trustee, means any officer of the Trustee, including any vice president, assistant vice president, secretary, assistant secretary, the treasurer, any assistant treasurer, the managing director or any other officer of the Trustee customarily performing functions similar to those performed by any of the above designated officers and also means, with respect to a particular corporate trust matter, any other officer to whom such matter is referred because of such officer’s knowledge of and familiarity with the particular subject.

“Restricted Securities” means the Securities defined as such in Section 2.3 hereof.

“Restricted Securities Legend” has the meaning set forth in Section 2.3(a) hereof.

“Rule 144” means Rule 144 under the Securities Act (including any successor rule thereof), as the same may be amended from time to time.

“Rule 144A” means Rule 144A as promulgated under the Securities Act (including any successor rule thereof), as the same may be amended from time to time.

“SEC” means the Securities and Exchange Commission.

“Securities” has the meaning ascribed to it in the first paragraph under the caption “Recitals of the Company.”

“Securities Act” means the Securities Act of 1933, as amended.

“Senior Debt” means the principal of, premium, if any, interest (including all interest accruing subsequent to the commencement of any bankruptcy or similar proceeding, whether or not a claim for post-petition interest is allowable as a claim in any such proceeding) and rent payable on or termination payment with respect to or in connection with, and all fees, costs, expenses and other amounts accrued or due on or in connection with, Indebtedness of the Company, whether outstanding on the date of this Indenture or thereafter created, incurred, assumed, guaranteed or in effect guaranteed by the Company (including all deferrals, renewals, extensions or refundings of, or amendments, modifications or supplements to, the foregoing), unless, in the case of any particular Indebtedness, the instrument creating or evidencing such Indebtedness or the assumption or guarantee thereof expressly provides that Indebtedness shall not be senior in right of payment to the Securities or expressly provides that such Indebtedness is pari passu or junior to the Securities. The Securities shall not be senior in right of payment to the

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outstanding 5% Convertible Subordinated Notes due February 2007 of the Company (the “February 2007 Notes”) or the 3 ¹/2% Convertible Subordinated Notes due October 2007 of the Company (the “October 2007 Notes”) and shall rank pari passu with the February 2007 Notes and the October 2007 Notes. Neither the February 2007 Notes nor the October 2007 Notes shall be Senior Debt, as that term is defined herein. Notwithstanding the foregoing, the term “Senior Debt” shall include, without limitation, all Designated Senior Debt, and shall not include Indebtedness of the Company to any Subsidiary.

“Significant Subsidiary” means any Subsidiary which is a “significant subsidiary” within the meaning of Rule 405 under the Securities Act.

“Special Record Date” for the payment of any Defaulted Interest means a date fixed by the Trustee pursuant to Section 2.17 hereof.

“Spinoff Securities” has the meaning specified in Section 12.4(d) hereof.

“Spinoff Valuation Period” has the meaning specified in Section 12.4(d) hereof.

“Stated Maturity” means the date specified in any Security as the fixed date for the payment of principal on such Security or on which an installment of interest (including Liquidated Damages, if any) on such Security is due and payable.

“Stock Price” means (i) in connection with a Fundamental Change in which the Holders receive only cash, the amount of cash paid per share of Common Stock in connection with the Fundamental Change, and (ii) in all other cases, the average of the Closing Prices of the Common Stock for each of the 20 Trading Days immediately prior to but not including the Fundamental Change Effective Date for such Fundamental Change.

“Subsidiary” means a corporation more than 50% of the outstanding voting stock of which is owned, directly or indirectly, by the Company or by one or more other Subsidiaries, or by the Company and one or more other Subsidiaries. For the purposes of this definition only, “voting stock” means stock which ordinarily has voting power for the election of directors, whether at all times or only so long as no senior class of stock has such voting power by reason of any contingency.

“TIA” means the Trust Indenture Act of 1939 (15 U.S. Code Section 77aaa-77bbbb), as in effect on the date of this Indenture; provided, however, that in the event the TIA is amended after such date, “TIA” means, to the extent required by such amendment, the Trust Indenture Act of 1939, as so amended, or any successor statute.

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“Trading Day” means any day on which the Nasdaq National Market or, if the Common Stock is not quoted on the Nasdaq National Market, the principal national securities exchange on which the Common Stock is listed, is open for trading or, if the Common Stock is not so listed, admitted for trading or quoted, any business day. A “Trading day” only includes those days that have a scheduled closing time of 4:00 p.m. (New York City time) or the then standard closing time for regular trading on the relevant exchange or trading system.

“Termination of Trading” means the occurrence of the Common Stock or any other common stock into which the Securities are then convertible being neither listed for trading on a United States national securities exchange nor approved for listing on the Nasdaq National Market or any similar U.S. system of automated dissemination of quotations of securities prices, or traded in over-the-counter securities markets, and no American Depositary Shares or similar instruments for such common stock are so listed or approved for listing in the United States.

“Transfer Agent” means any Person, which may be the Company, authorized by the Company to exchange or register the transfer of Securities.

“Trigger Event” has the meaning specified in Section 12.4(d) hereof.

“Trustee” means the Person named as the “Trustee” in the first paragraph of this instrument until a successor Trustee shall have become such pursuant to the applicable provisions of this Indenture, and thereafter “Trustee” shall mean such successor Trustee.

“U.S. Government Obligations” means: (1) direct obligations of the United States of America for the payment of which the full faith and credit of the United States of America is pledged or (2) obligations of a person controlled or supervised by and acting as an agency or instrumentality of the United States of America, the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States of America and which in either case, are non-callable at the option of the issuer thereof.

“Vice President,” when used with respect to the Company, means any vice president, whether or not designated by a number or a word or words added before or after the title “vice president.”

Section 1.2. Incorporation by Reference of Trust Indenture Act. Whenever this Indenture refers to a provision of the TIA, the provision is incorporated by reference in and made a part of this Indenture.

The following TIA terms used in this Indenture have the following meanings:

“indenture securities” means the Securities;

“indenture security holder” means a Holder;

“indenture to be qualified” means this Indenture;

“indenture trustee” or “institutional trustee” means the Trustee; and

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“obligor” on the Securities means the Company and any other obligor on the indenture securities.

All other TIA terms used in this Indenture that are defined by the TIA, defined by TIA reference to another statute or defined by SEC rule have the meanings assigned to them by such definitions.

Section 1.3. Rules of Construction. For all purposes of this Indenture, except as otherwise expressly provided or unless the context otherwise requires:

(a) the terms defined in this Article have the meanings assigned to them in this Article and include the plural as well as the singular;

(b) all accounting terms not otherwise defined herein have the meanings assigned to them in accordance with accounting principles generally accepted in the United States prevailing at the time of any relevant computation hereunder; and

(c) the words “herein,” “hereof” and “hereunder” and other words of similar import refer to this Indenture as a whole and not to any particular Article, Section or other subdivision.

ARTICLE II

THE SECURITIES

Section 2.1. Title and Terms. The Securities shall be known and designated as the “3.25% Convertible Subordinated Notes due 2012” of the Company. The aggregate principal amount of Securities which may be authenticated and delivered under this Indenture is limited to $275,000,000 (or $315,000,000 if the option set forth in Section 2 of the Purchase Agreement is exercised in full), except for securities authenticated and delivered upon registration of, transfer of, or in exchange for, or in lieu of other Securities pursuant to Section 2.7, 2.8, 2.9, 2.12, 7.5, 10.8, 11.1 or 12.2 hereof. The Securities shall be issuable in denominations of $1,000 or integral multiples thereof.

The Securities shall mature on September 28, 2012.

Interest shall accrue from September 28, 2005 at a rate of 3.25% per annum until the principal thereof is paid or made available for payment. Interest shall be payable semiannually in arrears on March 28 and September 28 of each year, commencing March 28, 2006, to Holders of record as of the close of business on the Regular Record Date for such interest payment.

Interest on the Securities shall be computed on the basis of a 360-day year of twelve 30-day months.

Principal of, and interest on, Global Securities shall be payable to the Depositary in immediately available funds.

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Principal on Physical Securities shall be payable at the office or agency of the Company maintained for such purpose, initially the Corporate Trust Office of the Trustee. Interest on Physical Securities will be payable by (i) check mailed to the address of the Person entitled thereto as such address shall appear in the Register, or (ii) upon application to the Registrar not later than the relevant Record Date by a Holder of an aggregate principal amount in excess of $5,000,000, wire transfer in immediately available funds.

The Securities shall be redeemable at the option of the Company as provided in Article X hereof.

The Securities shall have a Repurchase Right exercisable at the option of Holders as provided in Article XI hereof.

The Securities shall be convertible as provided in Article XII hereof.

The Securities shall be subordinated in right of payment to Senior Debt of the Company as provided in Article XIII hereof.

Section 2.2. Form of Securities. The Securities and the Trustee’s certificate of authentication to be borne by such Securities shall be substantially in the form annexed hereto as Exhibit A, which is incorporated in and made a part of this Indenture. The terms and provisions contained in the form of Security shall constitute, and are hereby expressly made, a part of this Indenture and to the extent applicable, the Company and the Trustee, by their execution and delivery of this Indenture, expressly agree to such terms and provisions and to be bound thereby.

Any of the Securities may have such letters, numbers or other marks of identification and such notations, legends and endorsements as the officers executing the same may approve (execution thereof to be conclusive evidence of such approval) and as are not inconsistent with the provisions of this Indenture, or as may be required to comply with any law or with any rule or regulation made pursuant thereto or with any rule or regulation of any securities exchange or automated quotation system on which the Securities may be listed or designated for issuance, or to conform to usage.

The Securities will be offered and sold only to QIBs in reliance on Rule 144A and shall be issued initially only in the form of one or more permanent Global Securities (each, a “Global Security”) in registered form without interest coupons. The Global Securities shall be:

(a) duly executed by the Company and authenticated by the Trustee as hereinafter provided;

(b) registered in the name of the Depositary (or its nominee) for credit to the respective accounts of the Holders at the Depositary; and

(c) deposited with the Trustee, as custodian for the Depositary.

The Global Securities shall be substantially in the form of Security set forth in Exhibit A annexed hereto (including the text and schedule called for by footnotes 1 and 2 thereto). The aggregate principal amount of the Global Securities may from time to time be increased or

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decreased by adjustments made on the records of the Trustee, as custodian for the Depositary (or its nominee), in accordance with the instructions given by the Holder thereof, as hereinafter provided.

Securities issued in exchange for interests in the Global Securities pursuant to Section 2.8(d) hereof shall be issued in the form of permanent definitive Securities (the “Physical Securities”) in registered form without interest coupons. The Physical Securities shall be substantially in the form set forth in Exhibit A annexed hereto.

The Securities shall be typed, printed, lithographed or engraved or produced by any combination of these methods or may be produced in any other manner permitted by the rules of any securities exchange on which the Securities may be listed, all as determined by the Officer executing such Securities, as evidenced by his/her execution of such Securities.

Section 2.3. Legends.

(a) Restricted Securities Legends. Each Security issued hereunder, and each share of Common Stock issuable upon conversion of Securities, shall, upon issuance, bear the legend set forth in Section 2.3(a)(i) or Section 2.3(a)(ii) (each, a “Restricted Securities Legend”), as the case may be, and such legend shall not be removed except as provided in Section 2.3(a)(iii). Each Security that bears or is required to bear the Restricted Securities Legend set forth in Section 2.3(a)(i) (together with any Common Stock issued upon conversion of the Securities and required to bear the Restricted Securities Legend set forth in Section 2.3(a)(ii), collectively, the “Restricted Securities”) shall be subject to the restrictions on transfer set forth in this Section 2.3(a) (including the Restricted Securities Legend set forth below), and the Holder of each such Restricted Security, by such Holder’s acceptance thereof, shall be deemed to have agreed to be bound by all such restrictions on transfer.

As used in Section 2.3(a), the term “transfer” encompasses any sale, pledge, transfer or other disposition whatsoever of any Restricted Security.

(i) Restricted Securities Legend for Securities. Except as provided in Section 2.3(a)(iii), until two years after the original issuance date of any Security, any certificate evidencing such Security (and all securities issued in exchange therefor or substitution thereof, other than Common Stock, if any, issued upon conversion thereof which shall bear the legend set forth in Section 2.3(a)(ii), if applicable) shall bear a Restricted Securities Legend in substantially the following form:

THE SECURITY EVIDENCED BY THIS CERTIFICATE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED OR SOLD EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE. BY ACQUISITION HEREOF, THE HOLDER (1) REPRESENTS THAT IT IS A “QUALIFIED INSTITUTIONAL BUYER” AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT; (2) AGREES THAT IT WILL NOT WITHIN TWO YEARS AFTER THE ORIGINAL ISSUANCE OF THIS SECURITY RESELL OR OTHERWISE

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TRANSFER THE SECURITY EVIDENCED HEREBY OR THE COMMON STOCK ISSUABLE UPON CONVERSION OF SUCH SECURITY EXCEPT (A) TO NEKTAR THERAPEUTICS (THE “COMPANY”) OR ANY SUBSIDIARY THEREOF, (B) TO A QUALIFIED INSTITUTIONAL BUYER IN COMPLIANCE WITH RULE 144A UNDER THE SECURITIES ACT, (C) PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE), (D) PURSUANT TO ANY OTHER AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT OR (E) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER; AND (3) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THE SECURITY EVIDENCED HEREBY IS TRANSFERRED (OTHER THAN A TRANSFER PURSUANT TO CLAUSE 2(E) ABOVE) A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. IN CONNECTION WITH ANY TRANSFER OF THE SECURITY EVIDENCED HEREBY WITHIN TWO YEARS AFTER THE ORIGINAL ISSUANCE OF SUCH SECURITY (OTHER THAN A TRANSFER PURSUANT TO CLAUSE (2)(E) ABOVE), THE HOLDER MUST CHECK THE APPROPRIATE BOX SET FORTH ON THE REVERSE HEREOF RELATING TO THE MANNER OF SUCH TRANSFER AND SUBMIT THIS CERTIFICATE TO THE TRUSTEE (OR ANY SUCCESSOR TRUSTEE, AS APPLICABLE). IF THE PROPOSED TRANSFER IS PURSUANT TO CLAUSE (2)(C) OR (2)(D) ABOVE, THE HOLDER MUST, PRIOR TO SUCH TRANSFER, FURNISH TO THE TRUSTEE (OR ANY SUCCESSOR TRUSTEE, AS APPLICABLE), SUCH CERTIFICATIONS, LEGAL OPINIONS OR OTHER INFORMATION AS THE COMPANY MAY REASONABLY REQUIRE TO CONFIRM THAT SUCH TRANSFER IS BEING MADE PURSUANT TO AN EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT. THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF THE SECURITY EVIDENCED HEREBY PURSUANT TO CLAUSE (2)(E) ABOVE OR THE EXPIRATION OF TWO YEARS FROM THE ORIGINAL ISSUANCE OF THE SECURITY EVIDENCED HEREBY.

(ii) Restricted Securities Legend for Common Stock Issued Upon Conversion of the Securities. Until two years after the original issuance date of any Security, any stock certificate representing Common Stock issued upon conversion of such Security shall bear a Restricted Securities Legend in substantially the following form:

THE SECURITY EVIDENCED HEREBY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED OR SOLD EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE. THE HOLDER HEREOF AGREES THAT UNTIL THE EXPIRATION OF TWO YEARS AFTER THE ORIGINAL ISSUANCE

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OF THE SECURITY UPON THE CONVERSION OF WHICH THE COMMON STOCK EVIDENCED HEREBY WAS ISSUED, (1) IT WILL NOT RESELL OR OTHERWISE TRANSFER THE SECURITY EXCEPT (A) TO NEKTAR THERAPEUTICS (THE “COMPANY”) OR ANY SUBSIDIARY THEREOF, (B) PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE) OR (C) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER; (2) PRIOR TO ANY SUCH TRANSFER OTHER THAN A TRANSFER PURSUANT TO CLAUSE 1(C) ABOVE, IT WILL FURNISH TO SUCH TRANSFER AGENT (OR ANY SUCCESSOR TRANSFER AGENT, AS APPLICABLE), SUCH CERTIFICATIONS, LEGAL OPINIONS OR OTHER INFORMATION AS THE COMPANY MAY REASONABLY REQUIRE TO CONFIRM THAT SUCH TRANSFER IS BEING MADE PURSUANT TO AN EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT; AND (3) IT WILL DELIVER TO EACH PERSON TO WHOM THE COMMON STOCK EVIDENCED HEREBY IS TRANSFERRED (OTHER THAN A TRANSFER PURSUANT TO A CLAUSE (1)(C) ABOVE) A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF THE COMMON STOCK EVIDENCED HEREBY PURSUANT TO CLAUSE (1)(C) ABOVE OR THE EXPIRATION OF TWO YEARS FROM THE ORIGINAL ISSUANCE OF THE SECURITY UPON THE CONVERSION OF WHICH THE COMMON STOCK EVIDENCED HEREBY WAS ISSUED.

(iii) Removal of the Restricted Securities Legends. Each Security or share of Common Stock issued upon conversion of such Security shall bear the Restricted Securities Legend set forth in Section 2.3(a)(i) or 2.3(a)(ii), as the case may be, until the earlier of:

(A) two years after the original issuance date of such Security;

(B) such Security or Common Stock has been sold pursuant to a registration statement that has been declared effective under the Securities Act (and which continues to be effective at the time of such sale); or

(C) such Common Stock has been issued upon conversion of Securities that have been sold pursuant to a registration statement that has been declared effective under the Securities Act (and which continues to be effective at the time of such sale).

The Holder must give notice thereof to the Trustee and any transfer agent for the Common Stock, as applicable.

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Notwithstanding the foregoing, the Restricted Securities Legend may be removed if there is delivered to the Company such satisfactory evidence, which may include an opinion of independent counsel, as may be reasonably required by the Company that neither such legend nor the restrictions on transfer set forth therein are required to ensure that transfers of such Security will not violate the registration requirements of the Securities Act. Upon provision of such satisfactory evidence, the Trustee, at the written direction of the Company, shall authenticate and deliver in exchange for such Securities another Security or Securities having an equal aggregate principal amount that does not bear such legend. If the Restricted Securities Legend has been removed from a Security as provided above, no other Security issued in exchange for all or any part of such Security shall bear such legend, unless the Company has reasonable cause to believe that such other Security is a “restricted security” within the meaning of Rule 144 and instructs the Trustee in writing to cause a Restricted Securities Legend to appear thereon.

Any Security (or security issued in exchange or substitution thereof) as to which such restrictions on transfer shall have expired in accordance with their terms or as to which the conditions for removal of the Restricted Securities Legend set forth in Section 2.3(a)(i) as set forth therein have been satisfied may, upon surrender of such Security for exchange to the Registrar in accordance with the provisions of Section 2.7 hereof, be exchanged for a new Security or Securities, of like tenor and aggregate principal amount, which shall not bear the Restricted Securities Legend required by Section 2.3(a)(i).

Any such Common Stock as to which such restrictions on transfer shall have expired in accordance with their terms or as to which the conditions for removal of the Restricted Securities Legend set forth in Section 2.3(a)(ii) as set forth therein have been satisfied may, upon surrender of the certificates representing such shares of Common Stock for exchange in accordance with the procedures of the transfer agent for the Common Stock, be exchanged for a new certificate or certificates for a like aggregate number of shares of Common Stock, which shall not bear the Restricted Securities Legend required by Section 2.3(a)(ii).

(b) Global Security Legend. Each Global Security shall also bear the following legend on the face thereof:

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (“DTC”) TO NEKTAR THERAPEUTICS (OR ITS SUCCESSOR) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, CONVERSION OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

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Section 2.4. Execution, Authentication, Delivery and Dating. An Officer shall execute the Securities on behalf of the Company by manual or facsimile signature. If the Officer whose signature is on a Security no longer holds that office at the time the Security is authenticated, the Security shall be valid nevertheless.

At any time and from time to time after the execution and delivery of this Indenture, the Company may deliver Securities executed by the Company to the Trustee for authentication, together with a Company Order for the authentication and delivery of such Securities, and the Trustee in accordance with such Company Order shall authenticate and deliver such Securities as in this Indenture provided and not otherwise.

Each Security shall be dated the date of its authentication.

No Security shall be entitled to any benefit under this Indenture, or be valid or obligatory for any purpose, unless there appears on such Security a certificate of authentication substantially in the form provided for herein executed by or on behalf of the Trustee by manual signature, and such certificate upon any Security shall be conclusive evidence, and the only evidence, that such Security has been duly authenticated and delivered hereunder.

The Trustee may appoint an authenticating agent or agents reasonably acceptable to the Company with respect to the Securities. Unless limited by the terms of such appointment, an authenticating agent may authenticate Securities whenever the Trustee may do so. Each reference in this Indenture to authentication by the Trustee includes authentication by such agent.

Section 2.5. Registrar and Paying Agent. The Company shall maintain an office or agency where Securities may be presented for registration of transfer or for exchange (the “Registrar”) and an office or agency where Securities may be presented for payment (the “Paying Agent”). The Registrar shall keep a register of the Securities (the “Register”) and of their transfer and exchange. The Company may appoint one or more co-Registrars and one or more additional Paying Agents for the Securities. The term “Paying Agent” includes any additional paying agent and the term “Registrar” includes any additional registrar. The Company may change any Paying Agent or Registrar without prior notice to any Holder.

The Company will cause each Paying Agent (other than the Trustee) to execute and deliver to the Trustee an instrument in which such Paying Agent shall agree with the Trustee, subject to the provisions of this Section, that such Paying Agent will:

(a) hold all sums held by it for the payment of the principal of or interest (including Liquidated Damages, if any) on Securities in trust for the benefit of the Persons entitled thereto until such sums shall be paid to such Persons or otherwise disposed of as provided in this Indenture;

(b) give the Trustee notice of any Default by the Company in the making of any payment of principal or interest (including Liquidated Damages, if any); and

(c) at any time during the continuance of any such Default, upon the written request of the Trustee, forthwith pay to the Trustee all sums so held in trust by such Paying Agent.

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The Company shall give prompt written notice to the Trustee of the name and address of any Paying Agent who is not a party to this Indenture. If the Company fails to appoint or maintain another entity as Registrar or Paying Agent, the Trustee shall act as such. The Company or any Affiliate of the Company may act as Paying Agent or Registrar; provided, however, that none of the Company, its subsidiaries or the Affiliates of the foregoing shall act:

(i) as Paying Agent in connection with redemptions, offers to purchase and discharges, as otherwise specified in this Indenture; and

(ii) as Paying Agent or Registrar if a Default or Event of Default has occurred and is continuing.

The Company hereby initially appoints the Trustee as Registrar and Paying Agent for the Securities.

Section 2.6. Paying Agent to Hold Assets in Trust. Not later than 12:00 p.m. (New York City time) on each due date of the principal and interest (including Liquidated Damages, if any) on any Securities, the Company shall deposit with one or more Paying Agents money in immediately available funds sufficient to pay such principal and interest (including Liquidated Damages, if any) so becoming due. The Company at any time may require a Paying Agent to pay all money held by it to the Trustee. Upon payment over to the Trustee, the Paying Agent (if other than the Company) shall have no further liability for the money so paid over to the Trustee.

If the Company shall act as a Paying Agent, it shall, prior to or on each due date of the principal of or interest (including Liquidated Damages, if any) on any of the Securities, segregate and hold in trust for the benefit of the Holders a sum sufficient with monies held by all other Paying Agents, to pay the principal or interest (including Liquidated Damages, if any) so becoming due until such sums shall be paid to such Persons or otherwise disposed of as provided in this Indenture, and shall promptly notify the Trustee of its action or failure to act.

Section 2.7. General Provisions Relating to Transfer and Exchange. The Securities are issuable only in registered form. A Holder may transfer a Security only by written application to the Registrar stating the name of the proposed transferee and otherwise complying with the terms of this Indenture. No such transfer shall be effected until, and such transferee shall succeed to the rights of a Holder only upon, final acceptance and registration of the transfer by the Registrar in the Register. Furthermore, any Holder of a Global Security shall, by acceptance of such Global Security, agree that transfers of beneficial interests in such Global Security may be effected only through a book-entry system maintained by the Holder of such Global Security (or its agent) and that ownership of a beneficial interest in the Security shall be required to be reflected in a book-entry. Notwithstanding the foregoing, in the case of a Restricted Security, a beneficial interest in a Global Security being transferred in reliance on an exemption from the registration requirements of the Securities Act other than in accordance with Rule 144 and Rule 144A may only be transferred for a Physical Security.

When Securities are presented to the Registrar with a request to register the transfer or to exchange them for an equal aggregate principal amount of Securities of other authorized denominations, the Registrar shall register the transfer or make the exchange as requested if its

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requirements for such transactions are met (including that such Securities are duly endorsed or accompanied by a written instrument of transfer duly executed by the Holder thereof or by an attorney who is authorized in writing to act on behalf of the Holder). Subject to Section 2.4 hereof, to permit registrations of transfers and exchanges, the Company shall execute and the Trustee shall authenticate Securities at the Registrar’s request. No service charge shall be made for any registration of transfer or exchange or redemption of the Securities, but the Company may require payment of a sum sufficient to cover any transfer tax or similar governmental charge payable in connection therewith (other than any such transfer taxes or other similar governmental charge payable upon exchanges pursuant to Section 2.14, 7.5 or 10.8 hereof).

Neither the Company nor the Registrar shall be required to exchange or register a transfer of any Securities:

(a) for a period of 15 Business Days prior to the day of any selection of Securities for redemption under Article X hereof;

(b) so selected for redemption or, if a portion of any Security is selected for redemption, such portion thereof selected for redemption; or

(c) surrendered for conversion or, if a portion of any Security is surrendered for conversion, such portion thereof surrendered for conversion.

Section 2.8. Book-Entry Provisions for the Global Securities.

(a) The Global Securities initially shall:

(i) be registered in the name of the Depositary (or a nominee thereof);

(ii) be delivered to the Trustee as custodian for such Depositary; and

(iii) bear the Restricted Securities Legend as set forth in Section 2.3(a)(i) hereof.

Members of, or participants in, the Depositary (“DTC Participants”) shall have no rights under this Indenture with respect to any Global Security held on their behalf by the Depositary, or the Trustee as its custodian, or under such Global Security, and the Depositary may be treated by the Company, the Trustee and any agent of the Company or the Trustee as the absolute owner of such Global Security for all purposes whatsoever. Notwithstanding the foregoing, nothing contained herein shall prevent the Company, the Trustee or any agent of the Company or Trustee from giving effect to any written certification, proxy or other authorization furnished by the Depositary or impair, as between the Depositary and the DTC Participants, the operation of customary practices governing the exercise of the rights of a Holder of any Security.

(b) The registered Holder of a Global Security may grant proxies and otherwise authorize any Person, including DTC Participants and Persons that may hold interests through DTC Participants, to take any action which a Holder is entitled to take under this Indenture or the Securities.

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(c) A Global Security may not be transferred, in whole or in part, to any Person other than the Depositary (or a nominee thereof), and no such transfer to any such other Person may be registered. Beneficial interests in a Global Security may be transferred in accordance with the rules and procedures of the Depositary and the provisions of Section 2.9 hereof.

(d) If at any time:

(i) the Depositary notifies the Company in writing that it is no longer willing or able to continue to act as Depositary for the Global Securities, or the Depositary ceases to be a “clearing agency” registered under the Exchange Act and a successor depositary for the Global Securities is not appointed by the Company within 90 days of such notice or cessation;

(ii) the Company, at its option, notifies the Trustee in writing that it elects to cause the issuance of the Securities in definitive form under this Indenture in exchange for all or any part of the Securities represented by a Global Security or Global Securities; or

(iii) an Event of Default has occurred and is continuing and the Registrar has received a request from the Depositary for the issuance of Physical Securities in exchange for such Global Security or Global Securities,

the Depositary shall surrender such Global Security or Global Securities to the Trustee for cancellation and the Company shall execute, and the Trustee, upon receipt of an Officers’ Certificate and Company Order for the authentication and delivery of Securities, shall authenticate and deliver in exchange for such Global Security or Global Securities, Physical Securities of like tenor as that of the Global Securities in an aggregate principal amount equal to the aggregate principal amount of such Global Security or Global Securities. Such Physical Securities shall be registered in such names as the Depositary shall identify in writing as the beneficial owners of the Securities represented by such Global Security or Global Securities (or any nominee thereof).

Notwithstanding the foregoing, in connection with any transfer of beneficial interests in a Global Security to beneficial owners pursuant to Section 2.8(d) hereof, the Registrar shall reflect on its books and records the date and a decrease in the principal amount of such Global Security in an amount equal to the principal amount of the beneficial interest in such Global Security to be transferred.

Section 2.9. Special Transfer Provisions. Unless a Security is transferred after the time period referred to in Rule 144(k) under the Securities Act or otherwise sold pursuant to a registration statement that has been declared effective under the Securities Act (and which continues to be effective at the time of such sale), the following provisions shall apply.

With respect to the registration of any proposed transfer of Securities to a QIB:

(a) If the Securities to be transferred consist of an interest in the Global Securities, the transfer of such interest may be effected only through the book-entry system maintained by the Depositary.

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(b) If the Securities to be transferred consist of Physical Securities, the Registrar shall register the transfer if such transfer is being made by a proposed transferor who has checked the box provided for on the form of Security stating, or has otherwise advised the Company and the Registrar in writing, that the sale has been made in compliance with the provisions of Rule 144A to a transferee who has signed the certification provided for on the form of Security stating or has otherwise advised the Company and the Registrar in writing that:

(i) it is purchasing the Securities for its own account or an account with respect to which it exercises sole investment discretion, in each case for investment and not with a view to distribution;

(ii) it and any such account is a QIB within the meaning of Rule 144A;

(iii) it is aware that the sale to it is being made in reliance on Rule 144A;

(iv) it acknowledges that it has received such information regarding the Company as it has requested pursuant to Rule 144A or has determined not to request such information; and

(v) it is aware that the transferor is relying upon its foregoing representations in order to claim the exemption from registration provided by Rule 144A.

In addition, the Registrar shall reflect on its books and records the date and an increase in the principal amount of the Global Securities in an amount equal to the principal amount of the Physical Securities to be transferred, and the Trustee shall cancel the Physical Securities so transferred.

By its acceptance of any Security bearing the Restricted Securities Legend, each Holder of such a Security acknowledges the restrictions on transfer of such Security set forth in this Indenture and agrees that it will transfer such Security only as provided in this Indenture. The Registrar shall not register a transfer of any Security unless such transfer complies with the restrictions on transfer of such Security set forth in this Indenture. The Registrar shall be entitled to receive and rely on written instructions from the Company verifying that such transfer complies with such restrictions on transfer. In connection with any transfer of Securities, each Holder agrees by its acceptance of the Securities to furnish the Registrar or the Company such certifications, legal opinions or other information as either of them may reasonably require to confirm that such transfer is being made pursuant to an exemption from, or a transaction not subject to, the registration requirements of the Securities Act; provided that the Registrar shall not be required to determine (but may rely on a determination made by the Company with respect to) the sufficiency of any such certifications, legal opinions or other information.

The Registrar shall retain copies of all letters, notices and other written communications received pursuant to Section 2.8 hereof or this Section 2.9. The Company shall have the right to inspect and make copies of all such letters, notices or other written communications at any reasonable time upon the giving of reasonable written notice to the Registrar.

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Section 2.10. Holder Lists. The Trustee shall preserve in as current a form as is reasonably practicable the most recent list available to it of the names and addresses of Holders and shall otherwise comply with Section 312(a) of the TIA. If the Trustee is not the Registrar, the Company shall furnish to the Trustee prior to or on each Interest Payment Date and at such other times as the Trustee may request in writing a list in such form and as of such date as the Trustee may reasonably require of the names and addresses of Holders relating to such Interest Payment Date or request, as the case may be.

Section 2.11. Persons Deemed Owners. The Company, the Trustee and any agent of the Company or the Trustee may treat the registered Holder of a Global Security as the absolute owner of such Global Security for the purpose of receiving payment thereof or on account thereof and for all other purposes whatsoever, whether or not such Security be overdue, and notwithstanding any notice of ownership or writing thereon, or any notice of previous loss or theft or other interest therein. The Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name any Security is registered as the owner of such Security for the purpose of receiving payment of principal of and interest (including Liquidated Damages, if any) on such Security and for all other purposes whatsoever, whether or not such Security be overdue, and notwithstanding any notice of ownership or writing thereon, or any notice of previous loss or theft or other interest therein.

Section 2.12. Mutilated, Destroyed, Lost or Stolen Securities. If any mutilated Security is surrendered to the Trustee, the Company shall execute and the Trustee shall authenticate and deliver in exchange therefor a new Security of like tenor and principal amount and bearing a number not contemporaneously outstanding.

If there is delivered to the Company and the Trustee

(a) evidence to their satisfaction of the destruction, loss or theft of any Security, and

(b) such security or indemnity as may be required by them to save each of them and any agent of either of them harmless, then, in the absence of notice to the Company or the Trustee that such Security has been acquired by a bona fide purchaser, the Company shall execute and, upon request, the Trustee shall authenticate and deliver, in lieu of any such destroyed, lost or stolen Security, a new Security of like tenor and principal amount and bearing a number not contemporaneously outstanding.

In case any such mutilated, destroyed, lost or stolen Security has become or is about to become due and payable, the Company in its discretion, but subject to any conversion rights, may, instead of issuing a new Security, pay such Security, upon satisfaction of the condition set forth in the preceding paragraph.

Upon the issuance of any new Security under this Section, the Company may require the payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in relation thereto and any other expenses (including the fees and expenses of the Trustee) connected therewith.

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Every new Security issued pursuant to this Section in lieu of any destroyed, lost or stolen Security shall constitute an original additional contractual obligation of the Company, whether or not the destroyed, lost or stolen Security shall be at any time enforceable by anyone, and such new Security shall be entitled to all the benefits of this Indenture equally and proportionately with any and all other Securities duly issued hereunder.

The provisions of this Section are exclusive and shall preclude (to the extent lawful) all other rights and remedies with respect to the replacement or payment of mutilated, destroyed, lost or stolen Securities.

Section 2.13. Treasury Securities. In determining whether the Holders of the requisite principal amount of Outstanding Securities are present at a meeting of Holders for quorum purposes or have given any request, demand, authorization, direction, notice, consent or waiver hereunder, Securities owned by the Company or any Affiliate of the Company shall be disregarded and deemed not to be Outstanding, except that, in determining whether the Trustee shall be protected in relying upon any such determination as to the presence of a quorum or upon any such request, demand, authorization, direction, notice, consent or waiver, only such Securities of which the Trustee has received written notice and are so owned shall be so disregarded.

Section 2.14. Temporary Securities. Pending the preparation of Securities in definitive form, the Company may execute and the Trustee shall, upon written request of the Company, authenticate and deliver temporary Securities (printed or lithographed). Temporary Securities shall be issuable in any authorized denomination, and substantially in the form of the Securities in definitive form but with such omissions, insertions and variations as may be appropriate for temporary Securities, all as may be determined by the Company. Every such temporary Security shall be executed by the Company and authenticated by the Trustee upon the same conditions and in substantially the same manner, and with the same effect, as the Securities in definitive form. Without unreasonable delay, the Company will execute and deliver to the Trustee Securities in definitive form (other than in the case of Securities in global form) and thereupon any or all temporary Securities (other than any such Securities in global form) may be surrendered in exchange therefor, at each office or agency maintained by the Company pursuant to Section 9.2 and the Trustee shall authenticate and deliver in exchange for such temporary Securities an equal aggregate principal amount of Securities in definitive form. Such exchange shall be made by the Company at its own expense and without any charge therefor. Until so exchanged, the temporary Securities shall in all respects be entitled to the same benefits and subject to the same limitations under this Indenture as Securities in definitive form authenticated and delivered hereunder.

Section 2.15. Cancellation. All securities surrendered for payment, redemption, repurchase, conversion, registration of transfer or exchange shall, if surrendered to any Person other than the Trustee, be delivered to the Trustee. All Securities so delivered shall be canceled promptly by the Trustee, and no Securities shall be issued in lieu thereof except as expressly permitted by any of the provisions of this Indenture. Upon written instructions of the Company, the Trustee shall destroy canceled Securities and, after such destruction, shall deliver a certificate of such destruction to the Company. If the Company shall acquire any of the Securities, such acquisition shall not operate as a redemption or satisfaction of the indebtedness represented by such Securities unless the same are delivered to the Trustee for cancellation.

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Section 2.16. CUSIP Numbers. The Company in issuing the Securities may use “CUSIP” numbers (if then generally in use), and the Trustee shall use CUSIP numbers in notices of redemption or exchange as a convenience to Holders; provided that any such notice shall state that no representation is made as to the correctness of such numbers either as printed on the Securities or as contained in any such notice and that reliance may be placed only on the other identification numbers printed on the Securities, and any such redemption shall not be affected by any defect in or omission of such numbers. The Company shall promptly notify the Trustee of any change in the CUSIP numbers.

Section 2.17. Defaulted Interest. If the Company fails to make a payment of interest (including Liquidated Damages, if any) on any Security when due and payable (“Defaulted Interest”), it shall pay such Defaulted Interest plus (to the extent lawful) any interest payable on the Defaulted Interest, in any lawful manner. It may elect to pay such Defaulted Interest, plus any such interest payable on it, to the Persons who are Holders of such Securities on which the interest is due on a subsequent Special Record Date. The Company shall notify the Trustee in writing of the amount of Defaulted Interest proposed to be paid on each such Security. The Company shall fix any such Special Record Date and payment date for such payment. At least 15 days before any such Special Record Date, the Company shall mail to Holders affected thereby a notice that states the Special Record Date, the Interest Payment Date, and amount of such interest (and such Liquidated Damages, if any) to be paid.

ARTICLE III

SATISFACTION AND DISCHARGE

Section 3.1. Satisfaction and Discharge of Indenture.

When:

(a) The Company shall deliver to the Trustee for cancellation all Securities previously authenticated (other than any Securities which have been destroyed, lost or stolen and in lieu of, or in substitution for which, other Securities shall have been authenticated and delivered) and not previously canceled, or

(b) (i) all the Securities not previously canceled or delivered to the Trustee for cancellation shall have become due and payable, or are by their terms to become due and payable within one year or have been called for redemption under arrangements satisfactory to the Trustee for the giving of notice of redemption,

(ii) the Company shall deposit with the Trustee, in trust, cash in U.S. dollars and/or U.S. Government Obligations which through the payment of interest and principal in respect thereof, in accordance with their terms, will provide (and without reinvestment and assuming no tax liability will be imposed on such Trustee), not later than one day before the due date of any payment of money, an amount in cash, sufficient, in the opinion of a nationally recognized firm of independent public accountants expressed in a

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written certification thereof delivered to the Trustee, to pay principal of or interest (including Liquidated Damages, if any) on all of the Securities (other than any Securities which shall have been mutilated, destroyed, lost or stolen and in lieu of or in substitution for which other Securities shall have been authenticated and delivered) not previously canceled or delivered to the Trustee for cancellation, on the dates such payments of principal or interest (including Liquidated Damages, if any) are due to such date of maturity or redemption, as the case may be, and

(iii) the Company shall have delivered to the Trustee an Officers’ Certificate and an Opinion of Counsel to the effect that (x) the Company has received from, or there has been published by, the Internal Revenue Service a ruling or (y) since the date of execution of this Indenture, there has been a change in the applicable federal income tax law, in the case of either clause (x) or (y) to the effect that, and based thereon such Opinion of Counsel shall confirm that, the Holders will not recognize income, gain or loss for federal income tax purposes as a result of such deposit and discharge and will be subject to federal income tax on the same amount and in the same manner and at the same times as would have been the case if such deposit and discharge had not occurred, and

if, in the case of either clause (1) or (2), the Company shall also pay or cause to be paid all other sums payable hereunder by the Company, then this Indenture shall cease to be of further effect (except as to:

(i) remaining rights of registration of transfer, substitution and exchange and conversion of Securities,

(ii) rights hereunder of Holders to receive payments of principal of and interest (including Liquidated Damages, if any) on, the Securities and the other rights, duties and obligations of Holders, as beneficiaries hereof with respect to the amounts, if any, so deposited with the Trustee, and

(iii) the rights, obligations and immunities of the Trustee hereunder),

and the Trustee, on demand of the Company accompanied by an Officers’ Certificate and an Opinion of Counsel and at the cost and expense of the Company, shall execute proper instruments acknowledging satisfaction of and discharging this Indenture; provided, however, the Company shall reimburse the Trustee for all amounts due the Trustee under Section 5.8 hereof and for any costs or expenses thereafter reasonably and properly incurred by the Trustee and to compensate the Trustee for any services thereafter reasonably and properly rendered by the Trustee in connection with this Indenture or the Securities.

Section 3.2. Deposited Monies to be Held in Trust. Subject to Section 3.3 hereof, all monies deposited with the Trustee pursuant to Section 3.1 hereof shall be held in trust and applied by it to the payment, notwithstanding the provisions of Article XIII hereof, either directly or through any Paying Agent (including the Company if acting as its own Paying Agent), to the Holders of the particular Securities for the payment or redemption of which such monies have been deposited with the Trustee, of all sums due and to become due thereon for principal and

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interest (including Liquidated Damages, if any). All monies deposited with the Trustee pursuant to Section 3.1 hereof (and held by it or any Paying Agent) for the payment of Securities subsequently converted shall be returned to the Company upon written request of the Company.

Section 3.3. Return of Unclaimed Monies. The Trustee and the Paying Agent shall pay to the Company any money held by them for the payment of principal or interest (including Liquidated Damages, if any) that remains unclaimed for two years after the date upon which such payment shall have become due. After payment to the Company, Holders entitled to the money must look to the Company for payment as general creditors unless an applicable abandoned property law designates another Person, and all liability of the Trustee and such Paying Agent with respect to such money shall cease.

ARTICLE IV

DEFAULTS AND REMEDIES

Section 4.1. Events of Default. An “Event of Default” with respect to the Securities occurs when any of the following occurs (whatever the reason for such Event of Default and whether it shall be occasioned by the provisions of Article XIII hereof or be voluntary or involuntary or be effected by operation of law or pursuant to any judgment, decree or order of any court or any order, rule or regulation of any administrative or governmental body):

(a) the Company defaults in the payment of the principal on any of the Securities when it becomes due and payable at Maturity, upon redemption or exercise of a Repurchase Right or otherwise, whether or not such payment is prohibited by Article XIII hereof; or

(b) the Company defaults in the payment of interest (including Liquidated Damages, if any) on any of the Securities when it becomes due and payable and such default continues for a period of 30 days, whether or not such payment is prohibited by Article XIII hereof; or

(c) the Company fails to deliver shares of Common Stock, together with cash instead of fractional shares, when such shares of Common Stock and cash instead of fractional shares are required to be delivered following conversion of a Security in accordance with Article XII, and such failure continues for 10 days; or

(d) the Company fails to perform or observe any other term, covenant or agreement contained in the Securities or this Indenture and the default continues for a period of 60 days after written notice of such failure, requiring the Company to remedy the same, shall have been given to the Company by the Trustee or to the Company and the Trustee by the Holders of at least 25% in aggregate principal amount of the Outstanding Securities; or

(e) (i) the Company fails to make any payment by the end of the applicable grace period, if any, after the maturity of any Indebtedness for borrowed money in an amount in excess of $25,000,000 (provided that such failure shall not constitute an Event

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of Default if (1) the Company determines, in good faith, that a lessor under a lease described in clause (3)(b) of the definition of Indebtedness breached a covenant under the lease and the Company has given notice of the breach to the lessor and the Trustee and (2) as a result of the breach, the Company withholds payment under the lease (a “Default Exception”)), or (ii) there is an acceleration of any Indebtedness for borrowed money in an amount in excess of $25,000,000 because of a default with respect to such Indebtedness (other than a Default Exception) without such Indebtedness having been discharged or such acceleration having been cured, waived, rescinded or annulled, in the case of either (i) or (ii) above, for a period of 30 days after written notice to the Company by the Trustee or to the Company and the Trustee by Holders of at least 25% in aggregate principal amount of the Outstanding Securities; or

(f) the Company fails to provide the Company Notice in accordance with the terms of Section 11.3(a) hereof; or

(g) the entry by a court having jurisdiction in the premises of (i) a decree or order for relief in respect of the Company in an involuntary case or proceeding under any applicable U.S. federal or state bankruptcy, insolvency, reorganization or other similar law or (ii) a decree or order adjudging the Company a bankrupt or insolvent, or approving as properly filed a petition seeking reorganization, arrangement, adjustment or composition of or in respect of the Company under any applicable U.S. federal or state law, or appointing a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or of any substantial part of its property, or ordering the winding up or liquidation of its affairs, and the continuance of any such decree or order for relief or any such other decree or order unstayed and in effect for a period of 60 consecutive days; or

(h) the commencement by the Company of a voluntary case or proceeding under any applicable U.S. federal or state bankruptcy, insolvency, reorganization or other similar law or of any other case or proceeding to be adjudicated a bankrupt or insolvent, or the consent by the Company to the entry of a decree or order for relief in respect of the Company in an involuntary case or proceeding under any applicable U.S. federal or state bankruptcy, insolvency, reorganization or other similar law or to the commencement of any bankruptcy or insolvency case or proceeding against the Company, or the filing by the Company of a petition or answer or consent seeking reorganization or relief under any applicable U.S. federal or state law, or the consent by the Company to the filing of such petition or to the appointment of or the taking possession by a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or of any substantial part of its property, or the making by the Company of an assignment for the benefit of creditors, or the admission by the Company in writing of its inability to pay its debts generally as they become due, or the taking of corporate action by the Company expressly in furtherance of any such action.

Section 4.2. Acceleration of Maturity; Rescission and Annulment. If an Event of Default with respect to Outstanding Securities (other than an Event of Default specified in Section 4.1(g) or 4.1(h) hereof) occurs and is continuing, the Trustee or the Holders of at least 25% in aggregate principal amount of the Outstanding Securities, by written notice to the Company, may declare

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due and payable 100% of the principal amount of all Outstanding Securities plus any accrued and unpaid interest to the date of payment. Upon a declaration of acceleration, such principal and accrued and unpaid interest to the date of payment shall be immediately due and payable.

If an Event of Default specified in Section 4.1(g) or 4.1(h) hereof occurs, all unpaid principal and accrued and unpaid interest (including Liquidated Damages, if any) on the Outstanding Securities shall become and be immediately due and payable, without any declaration or other act on the part of the Trustee or any Holder.

Any payments by the Company on the Securities following any such acceleration will be subject to the subordination provisions of Article XIII to the extent provided therein.

The Holders of a majority in aggregate principal amount of the Outstanding Securities by written notice to the Trustee and the Company may rescind and annul an acceleration and waive such defaults and their consequences if:

(a) all existing Events of Default, other than the nonpayment of principal of or interest on the Securities which have become due solely because of the acceleration, have been remedied, cured or waived,

(b) the rescission would not conflict with any judgment or decree of a court of competent jurisdiction, and

(c) the principal of any Securities which has become due otherwise than by such declaration of acceleration and any interest thereon at the rate or rates prescribed therefor has been deposited with the Trustee;

provided, however, that in the event such declaration of acceleration has been made based on the existence of an Event of Default under Section 4.1(e) hereof and such Event of Default has been remedied, cured or waived in accordance with Section 4.1(e) hereof, then, without any further action by the Holders, such declaration of acceleration shall be rescinded automatically and the consequences of such declaration shall be annulled. No such rescission or annulment shall affect any subsequent Default or impair any right consequent thereon.

Section 4.3. Other Remedies. If an Event of Default with respect to Outstanding Securities occurs and is continuing, the Trustee may pursue any available remedy by proceeding at law or in equity to collect the payment of principal of or interest on the Securities or to enforce the performance of any provision of the Securities.

The Trustee may maintain a proceeding in which it may prosecute and enforce all rights of action and claims under this Indenture or the Securities, even if it does not possess any of the Securities or does not produce any of them in the proceeding.

Section 4.4. Waiver of Past Defaults. The Holders, either (a) through the written consent of not less than a majority in aggregate principal amount of the Outstanding Securities, or (b) by the adoption of a resolution, at a meeting of Holders of the Outstanding Securities at which a quorum is present, by the Holders of at least a majority in aggregate principal amount of the

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Outstanding Securities represented at such meeting, may, on behalf of the Holders of all of the Securities, waive an existing Default or Event of Default, except a Default or Event of Default:

(a) in the payment of the principal of or interest (including Liquidated Damages, if any) on any Security (provided, however, that subject to Section 4.7 hereof, the Holders of a majority in aggregate principal amount of the Outstanding Securities may rescind an acceleration and its consequences, including any related payment default that resulted from such acceleration); or

(b) in respect of the right to convert any Security in accordance with Article XII; or

(c) in respect of a covenant or provision hereof which, under Section 7.2 hereof, cannot be modified or amended without the consent of the Holders of each Outstanding Security affected.

Upon any such waiver, such Default shall cease to exist, and any Event of Default arising therefrom shall be deemed to have been cured, for every purpose of this Indenture; provided, however, that no such waiver shall extend to any subsequent or other Default or impair any right consequent thereon.

Section 4.5. Control by Majority. The Holders either (a) through the written consent of not less than a majority in aggregate principal amount of the Outstanding Securities, or (b) by the adoption of a resolution, at a meeting of Holders of the Outstanding Securities at which a quorum is present, by the Holders of at least a majority in aggregate principal amount of the Outstanding Securities represented at such meeting, shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the Trustee or exercising any trust or power conferred on the Trustee. However, the Trustee may refuse to follow any direction that:

(a) conflicts with any law or with this Indenture;

(b) the Trustee determines may be unduly prejudicial to the rights of the Holders not joining therein, or

(c) may expose the Trustee to personal liability.

The Trustee may take any other action deemed proper by the Trustee which is not inconsistent with such direction.

Section 4.6. Limitation on Suit. No Holder of any Security shall have any right to pursue any remedy with respect to this Indenture or the Securities (including, instituting any proceeding, judicial or otherwise, with respect to this Indenture or for the appointment of a receiver or trustee) unless:

(a) such Holder has previously given written notice to the Trustee of an Event of Default that is continuing;

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(b) the Holders of at least 25% in aggregate principal amount of the Outstanding Securities shall have made written request to the Trustee to pursue the remedy;

(c) such Holder or Holders have furnished to the Trustee indemnity satisfactory to it against any costs, expenses and liabilities incurred in complying with such request;

(d) the Trustee has failed to comply with the request for 60 days after its receipt of such notice, request and furnishing of indemnity; and

(e) during such 60-day period, no direction inconsistent with such written request has been given to the Trustee by the Holders of a majority in aggregate principal amount of the Outstanding Securities (or such amount as shall have acted at a meeting pursuant to the provisions of this Indenture);

provided, however, that no one or more of such Holders may use this Indenture to prejudice the rights of another Holder or to obtain preference or priority over another Holder.

Section 4.7. Unconditional Rights of Holders to Receive Payment and to Convert. Notwithstanding any other provision in this Indenture, the Holder of any Security shall have the right, which is absolute and unconditional, to receive payment of the principal of and interest (including Liquidated Damages, if any) on such Security on the Stated Maturity expressed in such Security (or, in the case of redemption, on the Redemption Date, or in the case of the exercise of a Repurchase Right, on the Repurchase Date) and to convert such Security in accordance with Article XII, and to bring for the enforcement of any such payment on or after such respective dates and right to convert, and such rights shall not be impaired or affected without the consent of such Holder.

Section 4.8. Collection of Indebtedness and Suits for Enforcement by the Trustee. The Company covenants that if:

(a) a Default or Event of Default is made in the payment of any interest (including Liquidated Damages, if any) on any Security when such interest (including Liquidated Damages, if any) becomes due and payable and such Default or Event of Default continues for a period of 30 days, or

(b) a Default or Event of Default is made in the payment of the principal on any Security at the Maturity thereof,

the Company will, upon demand of the Trustee, pay to it, for the benefit of the Holders of such Securities, the whole amount then due and payable (as expressed therein or as a result of any acceleration effected pursuant to Section 4.2 hereof) on such Securities for principal and interest (including Liquidated Damages, if any) and, to the extent that payment of such interest shall be legally enforceable, interest on any overdue principal and on any overdue interest (including Liquidated Damages, if any), calculated using the rate of interest on the Security, and, in addition thereto, such further amount as shall be sufficient to cover the costs and expenses of collection, including the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel.

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If the Company fails to pay such amounts forthwith upon such demand, the Trustee, in its own name and as trustee of an express trust, may institute a judicial proceeding for the collection of the sums so due and unpaid, may prosecute such proceeding to judgment or final decree and may enforce the same against the Company and collect the moneys adjudged or decreed to be payable in the manner provided by law out of the property of the Company, wherever situated.

If an Event of Default occurs and is continuing, the Trustee may in its discretion proceed to protect and enforce its rights and the rights of the Holders of Securities by such appropriate judicial proceedings as the Trustee shall deem most effectual to protect and enforce any such rights, whether for the specific enforcement of any covenant or agreement in this Indenture or in aid of the exercise of any power granted herein, or to enforce any other proper remedy.

Section 4.9. Trustee May File Proofs of Claim. In case of the pendency of any receivership, insolvency, liquidation, bankruptcy, reorganization, arrangement, adjustment, composition or other judicial proceeding relative to the Company or the property of the Company or its creditors, the Trustee (irrespective of whether the principal of the Securities shall then be due and payable as therein expressed or by declaration or otherwise and irrespective of whether the Trustee shall have made any demand on the Company for the payment of overdue principal or interest (including Liquidated Damages, if any)) shall be entitled and empowered, by intervention in such proceeding or otherwise,

(a) to file and prove a claim for the whole amount of principal and interest (including Liquidated Damages, if any) owing and unpaid in respect of the Securities and to file such other papers or documents as may be necessary or advisable in order to have the claims of the Trustee (including any claim for the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel) and of the Holders of Securities allowed in such judicial proceeding, and

(b) to collect and receive any moneys or other property payable or deliverable on any such claim and to distribute the same;

and any Custodian or other similar official in any such judicial proceedings is hereby authorized by each Holder of Securities to make such payments to the Trustee and, in the event that the Trustee shall consent to the making of such payments directly to the Holders of Securities, to pay to the Trustee any amount due to it for the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel and any other amounts due the Trustee under Section 5.8.

Nothing contained herein shall be deemed to authorize the Trustee to authorize or consent to or accept, or adopt on behalf of any Holder of a Security, any plan of reorganization, arrangement, adjustment or composition affecting the Securities or the rights of any Holder thereof or to authorize the Trustee to vote in respect of the claim of any Holder of a Security in any such proceeding.

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Section 4.10. Restoration of Rights and Remedies. If the Trustee or any Holder of a Security has instituted any proceeding to enforce any right or remedy under this Indenture and such proceeding has been discontinued or abandoned for any reason, or has been determined adversely to the Trustee or to such Holder, then and in every such case, subject to any determination in such proceeding, the Company, the Trustee and the Holders of Securities shall be restored severally and respectively to their former positions hereunder and thereafter all rights and remedies of the Trustee and the Holders shall continue as though no such proceeding had been instituted.

Section 4.11. Rights and Remedies Cumulative. Except as otherwise provided with respect to the replacement or payment of mutilated, destroyed, lost or stolen Securities in the last paragraph of Section 2.12, no right or remedy conferred in this Indenture upon or reserved to the Trustee or to the Holders of Securities is intended to be exclusive of any other right or remedy, and every right and remedy shall, to the extent permitted by law, be cumulative and in addition to every other right and remedy given hereunder or hereafter existing at law or in equity or otherwise. The assertion or employment of any right or remedy hereunder, or otherwise, shall not prevent the concurrent assertion or employment of any other appropriate right or remedy.

Section 4.12. Delay or Omission Not Waiver. No delay or omission of the Trustee or of any Holder of any Security to exercise any right or remedy accruing upon any Event of Default shall impair any such right or remedy or constitute a waiver of any such Event of Default or any acquiescence therein. Every right and remedy given by this Article or by law to the Trustee or to the Holders of Securities may be exercised from time to time, and as often as may be deemed expedient, by the Trustee or by the Holders of Securities, as the case may be.

Section 4.13. Application of Money Collected. Subject to Article XIII, any money collected by the Trustee pursuant to this Article shall be applied in the following order, at the date or dates fixed by the Trustee and, in case of the distribution of such money on account of principal or interest (including Liquidated Damages, if any), upon presentation of the Securities and the notation thereon of the payment if only partially paid and upon surrender thereof if fully paid:

FIRST: To the payment of all amounts due the Trustee;

SECOND: To the payment of the amounts then due and unpaid for principal of and interest (including Liquidated Damages, if any) on the Securities in respect of which or for the benefit of which such money has been collected, ratably, without preference or priority of any kind, according to the amounts due and payable on such Securities for principal and interest (including Liquidated Damages, if any), respectively; and

THIRD: Any remaining amounts shall be repaid to the Company.

Section 4.14. Undertaking for Costs. All parties to this Indenture agree, and each Holder of any Security by such Holder’s acceptance thereof shall be deemed to have agreed, that any court may in its discretion require, in any suit for the enforcement of any right or remedy under this Indenture, or in any suit against the Trustee for any action taken, suffered or omitted by it as Trustee, the filing by any party litigant in such suit of an undertaking to pay the costs of such

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suit, and that such court may in its discretion assess reasonable costs, including reasonable attorneys’ fees, against any party litigant in such suit, having due regard to the merits and good faith of the claims or defenses made by such party litigant; but the provisions of this Section shall not apply to any suit instituted by the Company, to any suit instituted by the Trustee, to any suit instituted by any Holder, or group of Holders, holding in the aggregate more than 10% in aggregate principal amount of the Outstanding Securities, or to any suit instituted by any Holder of any Security for the enforcement of the payment of the principal of or interest (including Liquidated Damages, if any) on any Security on or after the Stated Maturity expressed in such Security (or, in the case of redemption or exercise of a Repurchase Right, on or after the Redemption Date) or for the enforcement of the right to convert any Security in accordance with Article XII.

Section 4.15. Waiver of Stay or Extension Laws. The Company covenants (to the extent that it may lawfully do so) that it will not at any time insist upon, or plead, or in any manner whatsoever claim to take the benefit or advantage of, any stay or extension law wherever enacted, now or at any time hereafter in force, which may affect the covenants or the performance of this Indenture; and the Company (to the extent that it may lawfully do so) hereby expressly waives all benefit or advantage of any such law and covenants that it will not hinder, delay or impede the execution of any power herein granted to the Trustee, but will suffer and permit the execution of every such power as though no such law had been enacted.

ARTICLE V

THE TRUSTEE

Section 5.1. Certain Duties and Responsibilities. (a) Except during the continuance of an Event of Default,

(i) The Trustee undertakes to perform such duties and only such duties as are specifically set forth in this Indenture or the TIA, and no implied covenants or obligations shall be read into this Indenture against the Trustee; and

(ii) In the absence of bad faith on its part, the Trustee may conclusively rely, as to the truth of the statements and the correctness of the opinions expressed therein, upon certificates or opinions furnished to the Trustee and conforming to the requirements of this Indenture; provided, however, that in the case of any such certificates or opinions which by any provision hereof are specifically required to be furnished to the Trustee, the Trustee shall examine the certificates or opinions to determine whether or not, on their face, they conform to the requirements to this Indenture (but need not investigate or confirm the accuracy of any facts stated therein).

(b) In case an Event of Default actually known to a Responsible Officer of the Trustee has occurred and is continuing, the Trustee shall exercise such of the rights and powers vested in it by this Indenture, and use the same degree of care and skill in their exercise, as a prudent person would exercise or use under the circumstances in the conduct of such person’s own affairs.

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(c) No provision of this Indenture shall be construed to relieve the Trustee from liability for its own negligent action, its own negligent failure to act, or its own willful misconduct, except that:

(i) This paragraph (c) shall not be construed to limit the effect of paragraph (a) of this Section 5.1;

(ii) The Trustee shall not be liable for any error of judgment made in good faith by a Responsible Officer, unless it shall be proved that the Trustee was negligent in ascertaining the pertinent facts; and

(iii) The Trustee shall not be liable with respect to any action taken or omitted to be taken by it in good faith in accordance with a direction received by it of the Holders of a majority in principal amount of the Outstanding Securities (or such lesser amount as shall have acted at a meeting pursuant to the provisions of this Indenture) relating to the time, method and place of conducting any proceeding for any remedy available to the Trustee, or exercising any trust or power conferred upon the Trustee, under this Indenture.

(d) Whether or not herein expressly so provided, every provision of this Indenture relating to the conduct or affecting the liability of or affording protection to the Trustee shall be subject to the provisions of this Section 5.1.

(e) No provision of this Indenture shall require the Trustee to expend or risk its own funds or otherwise incur any liability in the performance of any of its duties hereunder, or in the exercise of any of its rights or powers. The Trustee may refuse to perform any duty or exercise any right or power unless it receives indemnity reasonably satisfactory to it against any loss, liability, cost or expense (including, without limitation, reasonable fees of counsel).

(f) The Trustee shall not be obligated to pay interest on any money or other assets received by it unless otherwise agreed in writing with the Company. Assets held in trust by the Trustee need not be segregated from other funds except to the extent required by law.

(g) The Trustee shall not be bound to make any investigation into the facts or matters stated in any resolution, certificate, statement, instrument, opinion, report, notice, request, direction, consent, order, bond, debenture, note, coupon, other evidence of indebtedness or other paper or document, but the Trustee, in its discretion, may make such further inquiry or investigation into such facts or matters as it may see fit, and, if the Trustee shall determine to make such further inquiry or investigation, it shall be entitled to examine the books, records and premises of the Company, personally or by agent or attorney.

(h) The Trustee shall not be deemed to have notice or actual knowledge of any Event of Default or a Registration Default (as such term is defined in Section 3(a) of the Registration Rights Agreement) or the obligation of the Company to pay Liquidated Damages unless a Responsible Officer of the Trustee has actual knowledge thereof or unless written notice of any event which is in fact a Default is received by the Trustee pursuant to Section 14.2 hereof, and such notice references the Securities and this Indenture.

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(i) The rights, privileges, protections, immunities and benefits given to the Trustee hereunder, including, without limitation, its right to be indemnified, are extended to, and shall be enforceable by, the Trustee in each of its capacities hereunder, and each Paying Agent, authenticating agent, Conversion Agent or Registrar acting hereunder.

Section 5.2. Certain Rights of Trustee. Subject to the provisions of Section 5.1 hereof:

(a) The Trustee may rely on any document reasonably believed by it to be genuine and to have been signed or presented by the proper person. The Trustee need not investigate any fact or matter stated in the document.

(b) Before the Trustee acts or refrains from acting, it may require an Officers’ Certificate or an Opinion of Counsel, or both. The Trustee shall not be liable for any action it takes or omits to take in good faith in reliance on the Officers’ Certificate or Opinion of Counsel.

(c) The Trustee may act through attorneys and agents and shall not be responsible for the misconduct or negligence of any attorney or agent appointed with due care.

(d) The Trustee shall not be liable for any action taken or omitted to be taken by it in good faith which it believed to be authorized or within the discretion or rights or powers conferred upon it by this Indenture, unless the Trustee’s conduct constitutes negligence.

(e) The Trustee may consult with counsel of its selection and the written advice of such counsel as to matters of law shall be full and complete authorization and protection in respect of any action taken, omitted or suffered by it hereunder in good faith and in accordance with the advice or opinion of such counsel; provided, however, that the provisions shall not protect the Trustee from liability for its own negligence or willful misconduct.

(f) Unless otherwise specifically provided in this Indenture, any demand, request, direction or notice from the Company shall be sufficient if signed by an Officer of the Company.

(g) The permissive rights of the Trustee to do things enumerated in this Indenture shall not be construed as a duty unless so specified herein.

Section 5.3. Individual Rights of Trustee. The Trustee in its individual or any other capacity may become the owner or pledgee of Securities and may otherwise deal with the Company or any Affiliate of the Company with the same rights it would have if it were not Trustee. However, in the event that the Trustee acquires any conflicting interest (as such term is defined in Section 310(b) of the TIA), it must eliminate such conflict within 90 days, apply to the SEC for permission to continue as trustee (to the extent permitted under Section 310(b) of the TIA) or resign. Any agent may do the same with like rights and duties. The Trustee is also subject to Sections 5.11 and 5.12 hereof.

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Subject to the limitations imposed by the Trust Indenture Act, nothing in this Indenture shall prohibit the Trustee from becoming and acting as trustee under other indentures under which other securities, or certificates of interest of participation in other securities, of the Company are outstanding in the same manner as if it were not Trustee hereunder.

Section 5.4. Money Held in Trust. Money held by the Trustee in trust hereunder need not be segregated from other funds except to the extent required by law. The Trustee shall be under no liability for interest on any money received by it hereunder except as otherwise expressly agreed in writing with the Company.

Section 5.5. Trustee’s Disclaimer. The recitals contained herein and in the Securities (except for those in the certificate of authentication) shall be taken as the statements of the Company, and the Trustee assumes no responsibility for their correctness. The Trustee makes no representations as to the validity, sufficiency or priority of this Indenture or of the Securities. The Trustee shall not be accountable for the use or application by the Company of Securities or the proceeds thereof.

Section 5.6. Notice of Defaults. Within 90 days after the occurrence of any Default or Event of Default hereunder of which the Trustee has received written notice, the Trustee shall give notice to Holders pursuant to Section 14.2 hereof, unless such Default or Event of Default shall have been cured or waived; provided, however, that, except in the case of a Default or Event of Default in the payment of the principal of or interest (including Liquidated Damages, if any), or in the payment of any redemption or repurchase obligation on any Security, the Trustee shall be protected in withholding such notice if and so long as Responsible Officers of the Trustee in good faith determine that the withholding of such notice is in the interest of the Holders.

Section 5.7. Reports by Trustee to Holders. The Trustee shall transmit to Holders such reports concerning the Trustee and its actions under this Indenture as may be required by Section 313 of the TIA at the times and in the manner provided by the TIA.

A copy of each report at the time of its mailing to Holders shall be filed with the SEC, if required, and each stock exchange, if any, on which the Securities are listed. The Company shall promptly notify the Trustee when the Securities become listed on any stock exchange.

Section 5.8. Compensation and Indemnification. The Company covenants and agrees to pay to the Trustee from time to time, and the Trustee shall be entitled to, reasonable compensation (which shall not be limited by any provision of law in regard to the compensation of a trustee of an express trust) and the Company covenants and agrees to pay or reimburse the Trustee upon its request for all reasonable expenses, disbursements and advances incurred or made by or on behalf of it in accordance with any of the provisions of this Indenture (including the reasonable compensation and the expenses and disbursements of its counsel and of all agents and other persons not regularly in its employ), except to the extent that any such expense, disbursement or advance is due to its negligence or willful misconduct. When the Trustee incurs expenses or renders services in connection with an Event of Default specified in Section 4.1 hereof, the expenses (including the reasonable charges and expenses of its counsel) and the compensation for the services are intended to constitute expenses of administration under any

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bankruptcy law. The Company also covenants to indemnify the Trustee and its officers, directors, employees and agents for, and to hold such Persons harmless against, any loss, liability or expense incurred by them, arising out of or in connection with the acceptance or administration of this Indenture or the trusts hereunder or the performance of their duties hereunder, including the costs and expenses of defending themselves against or investigating any claim of liability in the premises, except to the extent that any such loss, liability or expense was due to the negligence or willful misconduct of such Persons. The obligations of the Company under this Section 5.8 to compensate and indemnify the Trustee and its officers, directors, employees and agents and to pay or reimburse such Persons for expenses, disbursements and advances shall constitute additional indebtedness hereunder and shall survive the satisfaction and discharge of this Indenture or the earlier resignation or removal of the Trustee. Such additional indebtedness shall be a senior claim to that of the Securities upon all property and funds held or collected by the Trustee as such, except funds held in trust for the benefit of the Holders of particular Securities, and the Securities are hereby subordinated to such senior claim. “Trustee” for purposes of this Section 5.8 shall include any predecessor Trustee, but the negligence or willful misconduct of any Trustee shall not affect the indemnification of any other Trustee.

Section 5.9. Replacement of Trustee. A resignation or removal of the Trustee and appointment of a successor Trustee shall become effective only upon the successor Trustee’s acceptance of appointment as provided in this Section 5.9.

The Trustee may resign and be discharged from the trust hereby created by so notifying the Company in writing. The Holders of at least a majority in aggregate principal amount of Outstanding Securities may remove the Trustee by so notifying the Trustee and the Company in writing. The Company must remove the Trustee if:

(a) the Trustee fails to comply with Section 5.11 hereof or Section 310 of the TIA;

(b) the Trustee becomes incapable of acting.

(c) the Trustee is adjudged a bankrupt or an insolvent or an order for relief is entered with respect to the Trustee under any Bankruptcy Law; or

(d) a Custodian or public officer takes charge of the Trustee or its property.

If the Trustee resigns or is removed or if a vacancy exists in the office of the Trustee for any reason, the Company shall promptly appoint a successor Trustee. The Trustee shall be entitled to payment of its fees and reimbursement of its expenses while acting as Trustee. Within one year after the successor Trustee takes office, the Holders of at least a majority in aggregate principal amount of Outstanding Securities may appoint a successor Trustee to replace the successor Trustee appointed by the Company.

In the event the Trustee fails to comply with Section 5.11 hereof, (a) the Company may remove the Trustee or (b) any Holder may, on behalf of himself or herself and all others similarly situated, petition any court of competent jurisdiction for the removal of the Trustee and the appointment of a successor Trustee.

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If an instrument of acceptance by a successor Trustee shall not have been delivered to the Trustee within 30 days after the giving of such notice of resignation or removal, the resigning or removed Trustee, as the case may be, may petition, at the expense of the Company, any court of competent jurisdiction for the appointment of a successor Trustee.

A successor Trustee shall deliver a written acceptance of its appointment to the retiring Trustee and to the Company. Thereupon the resignation or removal of the retiring Trustee shall become effective, and the successor Trustee shall have all the rights, powers and duties of the Trustee under this Indenture. The Company shall mail a notice of the successor Trustee’s succession to the Holders. The retiring Trustee shall promptly transfer all property held by it as Trustee to the successor Trustee. Notwithstanding replacement of the Trustee pursuant to this Section 5.9, the Company’s obligations under Section 5.8 hereof shall continue for the benefit of the retiring Trustee with respect to expenses, losses and liabilities incurred by it prior to such replacement.

Section 5.10. Successor Trustee by Merger, Etc. Subject to Section 5.11 hereof, if the Trustee consolidates with, merges or converts into, or transfers or sells all or substantially all of its corporate trust business to, another corporation or national banking association, the successor entity without any further act shall be the successor Trustee as to the Securities.

Section 5.11. Corporate Trustee Required; Eligibility. The Trustee shall at all times satisfy the requirements of Section 310(a)(1), (2) and (5) of the TIA. The Trustee shall at all times have (or, in the case of a corporation included in a bank holding company system, the related bank holding company shall at all times have), a combined capital and surplus of at least $100 million as set forth in its (or its related bank holding company’s) most recent published annual report of condition. The Trustee is subject to Section 310(b) of the TIA.

Section 5.12. Collection of Claims Against the Company. The Trustee is subject to Section 311(a) of the TIA, excluding any creditor relationship listed in Section 311(b) of the TIA. A Trustee who has resigned or been removed shall be subject to Section 311(a) of the TIA to the extent indicated therein.

ARTICLE VI

CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

Section 6.1. Company May Consolidate, Etc., Only on Certain Terms. The Company shall not consolidate with or merge into any other Person or convey, transfer or lease all or substantially all of its properties and assets to any Person, unless:

(a) it is the continuing corporation or the Person formed by such consolidation or into which the Company is merged or the Person which acquires by conveyance or transfer, or which leases, all or substantially all of the properties and assets of the Company is a corporation organized and validly existing under the laws of the United States of America, any State thereof or the District of Columbia and expressly assumes, by an indenture supplemental hereto, executed and delivered to the Trustee, in form reasonably satisfactory to the Trustee, the due and punctual payment of the principal of

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and interest (including Liquidated Damages, if any), on all the Securities and the performance of every covenant of this Indenture on the part of the Company to be performed or observed, which supplemental indenture shall provide for conversion rights in accordance with Section 12.11 hereof;

(b) at the time of consummation of such transaction, no Event of Default, and no event which, after notice or lapse of time or both, would become an Event of Default, shall have happened and be continuing;

(c) if as a result of such transaction the Securities become convertible into common stock or other securities issued by any Person other than the Company, such Person fully and unconditionally guarantees all obligations of the Company or the surviving or transferee entity under the Securities and this Indenture; and

(d) the Company shall have delivered to the Trustee an Officers’ Certificate and an Opinion of Counsel, each stating that such consolidation, merger, conveyance, transfer or lease and, if a supplemental indenture is required in connection with such transaction, such supplemental indenture comply with this Article and that all conditions precedent herein provided for relating to such transaction have been complied with.

Section 6.2. Successor Corporation Substituted. Upon any consolidation or merger by the Company with or into any other corporation or any conveyance, transfer or lease of the properties and assets of the Company substantially as an entirety to any Person, in accordance with Section 6.1 hereof, the successor corporation formed by such consolidation or into which the Company is merged or to which such conveyance, transfer or lease is made shall succeed to, and be substituted for, and may exercise every right and power of, the Company under this Indenture with the same effect as if such successor corporation had been named as the Company herein, and thereafter, except in the case of a lease to another Person, the predecessor corporation shall be relieved of all obligations and covenants under this Indenture and the Securities.

ARTICLE VII

AMENDMENTS, SUPPLEMENTS AND WAIVERS

Section 7.1. Without Consent of Holders of Securities. Without the consent of any Holders of Securities, the Company, when authorized by a Board Resolution, and the Trustee, at any time and from time to time, may amend this Indenture and the Securities to:

(a) add to the covenants of the Company for the benefit of the Holders of Securities;

(b) surrender any right or power herein conferred upon the Company;

(c) make provision with respect to the conversion rights of Holders of Securities pursuant to Section 12.11 hereof;

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(d) provide for the assumption of the Company’s obligations to the Holders of Securities in the case of a merger, consolidation, conveyance, transfer or lease pursuant to Article VI hereof;

(e) increase the Conversion Rate; provided, that such increase in the Conversion Rate shall not adversely affect the interests of the Holders of Securities (after taking into account tax and other consequences of such reduction) in any material respect;

(f) comply with the requirements of the SEC in order to effect or maintain the qualification of this Indenture under the TIA;

(g) make any changes or modifications to this Indenture necessary in connection with the registration of any Securities under the Securities Act as contemplated in the Registration Rights Agreement, provided, that such action pursuant to this clause (g) does not adversely affect the interests of the Holders of Securities in any material respect;

(h) cure any ambiguity or correct or supplement any defective provision herein, provided that such modification or amendment does not, in the good faith opinion of the Board of Directors and the Trustee, adversely affect the interests of the Holders of Securities in any material respect;

(i) add or modify any other provisions with respect to matters or questions arising under this Indenture which the Company and the Trustee may deem necessary or desirable and which shall not adversely affect the interests of the Holders of Securities in any material respect; or

(j) provide for Global Securities in addition to or in place of Physical Securities.

Section 7.2. With Consent of Holders of Securities. Except as provided below in this Section 7.2, this Indenture or the Securities may be amended or supplemented, and noncompliance in any particular instance with any provision of this Indenture or the Securities may be waived, in each case (i) with the written consent of the Holders of at least a majority in aggregate principal amount of the Outstanding Securities or (ii) by the adoption of a resolution, at a meeting of Holders of the Outstanding Securities at which a quorum is present, by the Holders of a majority in aggregate principal amount of the Outstanding Securities represented at such meeting.

Without the written consent or the affirmative vote of each Holder of Securities, an amendment or waiver under this Section 7.2 may not:

(a) change the Stated Maturity of the principal of, or any installment of interest (including Liquidated Damages, if any) on, any Security;

(b) reduce the principal amount of any Security;

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(c) reduce the rate of interest (including Liquidated Damages, if any) on any Security;

(d) change the currency of payment of principal of or interest (including Liquidated Damages, if any) on any Security;

(e) impair the right of any Holder to institute suit for the enforcement of any payment in or with respect to any Security;

(f) modify the obligation of the Company to maintain an office or agency in The City of New York pursuant to Section 9.2 hereof;

(g) except as permitted by Section 12.11 hereof, adversely affect the right to convert any Security as provided in Article XII hereof;

(h) adversely affect the Repurchase Right provided by Article XI hereof;

(i) modify the subordination provisions of the Securities in a manner adverse to the Holders of Securities;

(j) modify any of the provisions of this Section or Section 4.4, except to increase any percentage contained herein or therein or to provide that certain other provisions of this Indenture cannot be modified or waived without the consent of the Holder of each Outstanding Security affected thereby; or

(k) reduce the requirements of Section 8.4 hereof for quorum or voting, or reduce the percentage in aggregate principal amount of the Outstanding Securities the consent of whose Holders is required for any such supplemental indenture or the consent of whose Holders is required for any waiver provided for in this Indenture.

It shall not be necessary for any Act of Holders of Securities under this Section to approve the particular form of any proposal supplemental indenture, but it shall be sufficient if such Act shall approve the substance thereof.

Section 7.3. Compliance with Trust Indenture Act. Every amendment to this Indenture or the Securities shall be set forth in a supplemental indenture that complies with the TIA as then in effect.

Section 7.4. Revocation of Consents and Effect of Consents or Votes. Until an amendment, supplement or waiver becomes effective, a written consent to it by a Holder is a continuing consent by the Holder and every subsequent Holder of a Security or portion of a Security that evidences the same debt as the consenting Holder’s Security, even if notation of the consent is not made on any Security; provided, however, that unless a record date shall have been established, any such Holder or subsequent Holder may revoke the consent as to its Security or portion of a Security if the Trustee receives written notice of revocation before the date the amendment, supplement or waiver becomes effective.

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An amendment, supplement or waiver becomes effective on receipt by the Trustee of written consents from or affirmative votes by, as the case may be, the Holders of the requisite percentage of aggregate principal amount of the Outstanding Securities, and thereafter shall bind every Holder of Securities; provided, however, if the amendment, supplement or waiver makes a change described in any of the clauses (a) through (k) of Section 7.2 hereof, the amendment, supplement or waiver shall bind only each Holder of a Security which has consented to it or voted for it, as the case may be, and every subsequent Holder of a Security or portion of a Security that evidences the same indebtedness as the Security of the consenting or affirmatively voting, as the case may be, Holder.

Section 7.5. Notation on or Exchange of Securities. If an amendment, supplement or waiver changes the terms of a Security:

(a) the Trustee may require the Holder of a Security to deliver such Securities to the Trustee, the Trustee may place an appropriate notation on the Security about the changed terms and return it to the Holder and the Trustee may place an appropriate notation on any Security thereafter authenticated; or

(b) if the Company or the Trustee so determines, the Company in exchange for the Security shall issue and the Trustee shall authenticate a new Security that reflects the changed terms.

Failure to make the appropriate notation or issue a new Security shall not affect the validity and effect of such amendment, supplement or waiver.

Section 7.6. Trustee to Sign Amendment, Etc. The Trustee shall sign any amendment authorized pursuant to this Article VII if the amendment does not adversely affect the rights, duties, liabilities or immunities of the Trustee in any material respects. If the amendment does adversely affect the rights, duties, liabilities or immunities of the Trustee, the Trustee may but need not sign it. In signing or refusing to sign such amendment, the Trustee shall be entitled to receive and shall be fully protected in relying upon an Officers’ Certificate and an Opinion of Counsel as conclusive evidence that such amendment is authorized or permitted by this Indenture.

ARTICLE VIII

MEETING OF HOLDERS OF SECURITIES

Section 8.1. Purposes for Which Meetings May Be Called. A meeting of Holders of Securities may be called at any time and from time to time pursuant to this Article to make, give or take any request, demand, authorization, direction, notice, consent, waiver or other action provided by this Indenture to be made, given or taken by Holders of Securities.

Notwithstanding anything contained in this Article VIII, the Trustee may, during the pendency of a Default or an Event of Default, call a meeting of Holders of Securities in accordance with its standard practices.

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Section 8.2. Call Notice and Place of Meetings. (a) The Trustee may at any time call a meeting of Holders of Securities for any purpose specified in Section 8.1 hereof, to be held at such time and at such place in The City of New York. Notice of every meeting of Holders of Securities, setting forth the time and the place of such meeting and in general terms the action proposed to be taken at such meeting, shall be given, in the manner provided in Section 14.2 hereof, not less than 21 nor more than 180 days prior to the date fixed for the meeting.

(b) In case at any time the Company, pursuant to a Board Resolution, or the Holders of at least 10% in principal amount of the Outstanding Securities shall have requested the Trustee to call a meeting of the Holders of Securities for any purpose specified in Section 8.1 hereof, by written request setting forth in reasonable detail the action proposed to be taken at the meeting, and the Trustee shall not have made the first publication of the notice of such meeting within 21 days after receipt of such request or shall not thereafter proceed to cause the meeting to be held as provided herein, then the Company or the Holders of Securities in the amount specified, as the case may be, may determine the time and the place in The City of New York for such meeting and may call such meeting for such purposes by giving notice thereof as provided in paragraph (a) of this Section.

Section 8.3. Persons Entitled to Vote at Meetings. To be entitled to vote at any meeting of Holders of Securities, a Person shall be (a) a Holder of one or more Outstanding Securities, or (b) a Person appointed by an instrument in writing as proxy for a Holder or Holders of one or more Outstanding Securities by such Holder or Holders. The only Persons who shall be entitled to be present or to speak at any meeting of Holders shall be the Persons entitled to vote at such meeting and their counsel, any representatives of the Trustee and its counsel and any representatives of the Company and its counsel.

Section 8.4. Quorum; Action. The Persons entitled to vote a majority in principal amount of the Outstanding Securities shall constitute a quorum. In the absence of a quorum within 30 minutes of the time appointed for any such meeting, the meeting shall, if convened at the request of Holders of Securities, be dissolved. In any other case, the meeting may be adjourned for a period of not less than 10 days as determined by the chairman of the meeting prior to the adjournment of such meeting. In the absence of a quorum at any such adjourned meeting, such adjourned meeting may be further adjourned for a period of not less than 10 days as determined by the chairman of the meeting prior to the adjournment of such adjourned meeting. Notice of the reconvening of any adjourned meeting shall be given as provided in Section 8.2(a) hereof, except that such notice need be given only once and not less than five days prior to the date on which the meeting is scheduled to be reconvened. Notice of the reconvening of an adjourned meeting shall state expressly the percentage of the principal amount of the Outstanding Securities which shall constitute a quorum.

Subject to the foregoing, at the reconvening of any meeting adjourned for a lack of a quorum, the Persons entitled to vote 25% in principal amount of the Outstanding Securities at the time shall constitute a quorum for the taking of any action set forth in the notice of the original meeting.

At a meeting or an adjourned meeting duly reconvened and at which a quorum is present as aforesaid, any resolution and all matters (except as limited by the proviso to Section 7.2

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hereof) shall be effectively passed and decided if passed or decided by the Persons entitled to vote not less than a majority in principal amount of Outstanding Securities represented and voting at such meeting.

Any resolution passed or decisions taken at any meeting of Holders of Securities duly held in accordance with this Section shall be binding on all the Holders of Securities, whether or not present or represented at the meeting.

Section 8.5. Determination of Voting Rights; Conduct and Adjournment of Meetings. (a) Notwithstanding any other provisions of this Indenture, the Trustee may make such reasonable regulations as it may deem advisable for any meeting of Holders of Securities in regard to proof of the holding of Securities and of the appointment of proxies and in regard to the appointment and duties of inspectors of votes, the submission and examination of proxies, certificates and other evidence of the right to vote, and such other matters concerning the conduct of the meeting as it shall deem appropriate. Except as otherwise permitted or required by any such regulations, the holding of Securities shall be proved in the manner specified in Section 2.2 hereof and the appointment of any proxy shall be proved in the manner specified in Section 2.2 hereof. Such regulations may provide that written instruments appointing proxies, regular on their face, may be presumed valid and genuine without the proof specified in Section 2.2 hereof or other proof.

(b) The Trustee shall, by an instrument in writing, appoint a temporary chairman (which may be the Trustee) of the meeting, unless the meeting shall have been called by the Company or by Holders of Securities as provided in Section 8.2(b) hereof, in which case the Company or the Holders of Securities calling the meeting, as the case may be, shall in like manner appoint a temporary chairman. A permanent chairman and a permanent secretary of the meeting shall be elected by vote of the Persons entitled to vote a majority in principal amount of the Outstanding Securities represented at the meeting.

(c) At any meeting each Holder of a Security or proxy shall be entitled to one vote for each $1,000 principal amount of Securities held or represented by him; provided, however, that no vote shall be cast or counted at any meeting in respect of any Security challenged as not Outstanding and ruled by the chairman of the meeting to be not Outstanding. The chairman of the meeting shall have no right to vote, except as a Holder of a Security or proxy.

(d) Any meeting of Holders of Securities duly called pursuant to Section 8.2 hereof at which a quorum is present may be adjourned from time to time by Persons entitled to vote a majority in principal amount of the Outstanding Securities represented at the meeting, and the meeting may be held as so adjourned without further notice.

Section 8.6. Counting Votes and Recording Action of Meetings. The vote upon any resolution submitted to any meeting of Holders of Securities shall be by written ballots on which shall be subscribed the signatures of the Holders of Securities or of their representatives by proxy and the principal amounts and serial numbers of the Outstanding Securities held or represented by them. The permanent chairman of the meeting shall appoint two inspectors of votes who shall count all votes cast at the meeting for or against any resolution and who shall make and file with the secretary of the meeting their verified written reports in duplicate of all votes cast at the

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meeting. A record, at least in duplicate, of the proceedings of each meeting of Holders of Securities shall be prepared by the secretary of the meeting and there shall be attached to said record the original reports of the inspectors of votes on any vote by ballot taken thereat and affidavits by one or more Persons having knowledge of the facts setting forth a copy of the notice of the meeting and showing that said notice was given as provided in Section 8.2 hereof and, if applicable, Section 8.4 hereof. Each copy shall be signed and verified by the affidavits of the permanent chairman and secretary of the meeting and one such copy shall be delivered to the Company and another to the Trustee to be preserved by the Trustee, the latter to have attached thereto the ballots voted at the meeting. Any record so signed and verified shall be conclusive evidence of the matters therein stated.

ARTICLE IX

COVENANTS

Section 9.1. Payment of Principal and Interest. The Company will duly and punctually pay the principal of and interest (including Liquidated Damages, if any) in respect of the Securities in accordance with the terms of the Securities and this Indenture. The Company will deposit or cause to be deposited with the Trustee as directed by the Trustee, no later than the day of the Stated Maturity of any Security or installment of interest (including Liquidated Damages, if any), all payments so due.

Section 9.2. Maintenance of Offices or Agencies. The Company hereby appoints the Trustee’s Corporate Trust Office as its office in The City of New York, where Securities may be:

(a) presented or surrendered for payment;

(b) surrendered for registration of transfer or exchange;

(c) surrendered for conversion;

and where notices and demands to or upon the Company in respect of the Securities and this Indenture may be served.

The Company may at any time and from time to time vary or terminate the appointment of any such office or appoint any additional offices for any or all of such purposes; provided, however, that until all of the Securities have been delivered to the Trustee for cancellation, or moneys sufficient to pay the principal of and interest (including Liquidated Damages, if any) on the Securities have been made available for payment and either paid or returned to the Company pursuant to the provisions of Section 3.3 hereof, the Company will maintain in The City of New York, an office or agency where Securities may be presented or surrendered for payment, where Securities may be surrendered for registration of transfer or exchange, where Securities may be surrendered for conversion and where notices and demands to or upon the Company in respect of the Securities and this Indenture may be served. The Company will give prompt written notice to the Trustee, and notice to the Holders in accordance with Section 14.2 hereof, of the appointment or termination of any such agents and of the location and any change in the location of any such office or agency.

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If at any time the Company shall fail to maintain any such required office or agency in The City of New York, or shall fail to furnish the Trustee with the address thereof, presentations and surrenders may be made at, and notices and demands may be served on, the Corporate Trust Office of the Trustee.

Section 9.3. Corporate Existence. Subject to Article VI hereof, the Company will do or cause to be done all things necessary to preserve and keep in full force and effect its corporate existence, rights (charter and statutory) and franchises; provided, however, that the Company shall not be required to preserve any such right or franchise if the Company determines that the preservation thereof is no longer desirable in the conduct of the business of the Company and that the loss thereof is not disadvantageous in any material respect to the Holders.

Section 9.4. Maintenance of Properties. The Company will maintain and keep its properties and every part thereof in such repair, working order and condition, and make or cause to be made all such needful and proper repairs, renewals and replacements thereto, as in the judgment of the Company are necessary in the interests of the Company; provided, however, that nothing contained in this Section shall prevent the Company from selling, abandoning or otherwise disposing of any of its properties or discontinuing a part of its business from time to time if, in the judgment of the Company, such sale, abandonment, disposition or discontinuance is advisable and does not materially adversely affect the interests or business of the Company.

Section 9.5. Payment of Taxes and Other Claims. The Company will, and will cause any Significant Subsidiary to, promptly pay and discharge or cause to be paid and discharged all material taxes, assessments and governmental charges or levies lawfully imposed upon it or upon its income or profits or upon any of its property, real or personal, or upon any part thereof, as well as all material claims for labor, materials and supplies which, if unpaid, might by law become a lien or charge upon its property; provided, however, that neither the Company nor any Significant Subsidiary shall be required to pay or discharge or cause to be paid or discharged any such tax, assessment, charge, levy, or claim if the amount, applicability or validity thereof shall currently be contested in good faith by appropriate proceedings and if the Company or such Significant Subsidiary, as the case may be, shall have set aside on its books reserves deemed by it adequate with respect thereto.

Section 9.6. Reports. (a) The Company shall deliver to the Trustee within 15 days after it files them with the SEC copies of the annual reports and of the information, documents, and other reports (or copies of such portions of any of the foregoing as the SEC may by rules and regulations prescribe) which the Company is required to file with the SEC pursuant to Section 13 or 15(d) of the Exchange Act; provided, however, the Company shall not be required to deliver to the Trustee any materials for which the Company has sought and received confidential treatment by the SEC. The Company also shall comply with the other provisions of Section 314(a) of the TIA.

(b) If at any time the Company is not subject to Section 13 or 15(d) of the Exchange Act, upon the request of a Holder of a Security, the Company will promptly furnish or cause to be furnished to such Holder or to a prospective purchaser of such Security designated by such Holder, as the case may be, the information, if any, required to be delivered by it pursuant to Rule 144A(d)(4) under the Securities Act to permit compliance with Rule 144A in connection

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with the resale of such Security; provided, however, that the Company shall not be required to furnish such information in connection with any request made on or after the date which is two years from the later of the date such security was last acquired from the Company or an “affiliate” of the Company.

Section 9.7. Compliance Certificate. The Company shall deliver to the Trustee, within 120 days after the end of each fiscal year of the Company, an Officers’ Certificate stating that in the course of the performance by the signers of their duties as Officers of the Company, they would normally have knowledge of any failure by the Company to comply with all conditions, or Default by the Company with respect to any covenants, under this Indenture, and further stating whether or not they have knowledge of any such failure or default and, if so, specifying each such failure or Default and the nature thereof. In the event an Officer of the Company comes to have actual knowledge of a Default, regardless of the date, the Company shall deliver, within five Business Days of such Officer having become aware of such Default, an Officers’ Certificate to the Trustee specifying such Default and the nature and status thereof.

Section 9.8. Resale of Certain Securities. During the period of two years after the last date of original issuance of any Securities, the Company shall not, and shall not permit any of its “affiliates” (as defined under Rule 144 under the Securities Act) to, resell any Securities, or shares of Common Stock issuable upon conversion of the Securities, which constitute “restricted securities” under Rule 144, that are acquired by any of them within the United States or to “U.S. persons” (as defined in Regulation S) except pursuant to an effective registration statement under the Securities Act or an applicable exemption therefrom. The Trustee shall have no responsibility or liability in respect of the Company’s performance of its agreement in the preceding sentence.

ARTICLE X

REDEMPTION OF SECURITIES

Section 10.1. Redemption. The Securities are not redeemable prior to September 28, 2008. On and after September 28, 2008, the Company may, at its option, redeem the Securities in whole or in part on any date from time to time, upon notice as set forth in Section 10.5, at a Redemption Price, payable in cash, equal to $1,000 per $1,000 principal amount of the Securities redeemed (the “Redemption Price”), plus any interest (including Liquidated Damages, if any) accrued but not paid prior to, but excluding, the date of redemption (the “Redemption Date”) if the Closing Price of the Common Stock has exceeded 150% of the Conversion Price (as defined in Article XII and as such may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30-Trading Day period ending on the Trading Day prior to the date of mailing of the notice of redemption pursuant to Section 10.5 (such redemption, a “Redemption”).

Section 10.2. [Reserved]

Section 10.3. Notice to Trustee. If the Company elects to redeem Securities pursuant to the redemption provisions of Section 10.1 hereof, it shall notify the Trustee at least (i) 35 days prior to the Redemption Date in the event the Company elects to have the Trustee provide the

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notice of redemption to Holders specified in Section 10.5 hereof or (ii) 30 days prior to the Redemption Date in the event that the Company elects to provide such notice of redemption, of such intended Redemption Date, of the principal amount of Securities to be redeemed and of the CUSIP numbers of the Securities to be redeemed, or, in either case, such fewer number of days as may be agreed upon by the Company and the Trustee.

Section 10.4. Selection of Securities to Be Redeemed. If fewer than all the Securities are to be redeemed, the Trustee shall select the particular Securities to be redeemed from the Outstanding Securities by a method that complies with the requirements of any exchange on which the Securities are listed, or, if the Securities are not listed on an exchange, on a pro rata basis or by lot or in accordance with any other method the Trustee considers fair and appropriate. Securities and portions thereof that the Trustee selects shall be in amounts equal to the minimum authorized denominations for Securities to be redeemed or any integral multiple thereof.

If any Security selected for partial redemption is converted in part before termination of the conversion right with respect to the portion of the Security so selected, the converted portion of such Security shall be deemed to be the portion selected for redemption (provided, however, that the Holder of such Security so converted and deemed redeemed shall not be entitled to any additional interest payment as a result of such deemed redemption than such Holder would have otherwise been entitled to receive upon conversion of such Security). Securities which have been converted during a selection of Securities to be redeemed may be treated by the Trustee as Outstanding for the purpose of such selection.

The Trustee shall promptly notify the Company and the Registrar in writing of the Securities selected for redemption and, in the case of any Securities selected for partial redemption, the principal amount thereof to be redeemed.

For all purposes of this Indenture, unless the context otherwise requires, all provisions relating to the redemption of Securities shall relate, in the case of any Securities redeemed or to be redeemed only in part, to the portion of the principal amount of such Securities which has been or is to be redeemed.

Section 10.5. Notice of Redemption. Notice of redemption shall be given in the manner provided in Section 14.2 hereof to the Holders of Securities to be redeemed. Such notice shall be given not less than 30 nor more than 60 days prior to the Redemption Date.

All notices of redemption shall state:

(a) the Redemption Date;

(b) the Redemption Price and interest accrued and unpaid to the Redemption Date, if any;

(c) if fewer than all the Outstanding Securities are to be redeemed, the aggregate principal amount of Securities to be redeemed and the aggregate principal amount of Securities which will be outstanding after such partial redemption;

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(d) that on the Redemption Date the Redemption Price and interest accrued and unpaid to the Redemption Date, if any, will become due and payable upon each such Security to be redeemed, and that interest thereon shall cease to accrue on and after such date;

(e) the Conversion Rate, the date on which the right to convert the principal of the Securities to be redeemed will terminate and the places where such Securities may be surrendered for conversion;

(f) the place or places where such Securities are to be surrendered for payment of the Redemption Price and accrued and unpaid interest, if any; and

(g) the CUSIP number of the Securities.

The notice given shall specify the last date on which exchanges or transfers of Securities may be made pursuant to Section 2.1 hereof, and shall specify the serial numbers of Securities and the portions thereof called for redemption.

Notice of redemption of Securities to be redeemed at the election of the Company shall be given by the Company or, at the Company’s request, by the Trustee in the name of and at the expense of the Company.

Section 10.6. Effect of Notice of Redemption. Notice of redemption having been given as provided in Section 10.5 hereof, the Securities so to be redeemed shall, on the Redemption Date, become due and payable at the Redemption Price therein specified and from and after such date (unless the Company shall default in the payment of the Redemption Price and accrued and unpaid interest) such Securities shall cease to bear interest. Upon surrender of any such Security for redemption in accordance with such notice, such Security shall be paid by the Company at the Redemption Price; provided, however, the installments of interest on Securities whose Stated Maturity is prior to or on the Redemption Date shall be payable to the Holders of such Securities, or one or more Predecessor Securities, registered as such on the relevant Record Date according to their terms and the provisions of Section 2.1 hereof.

If any Security called for redemption shall not be so paid upon surrender thereof for redemption, the principal shall, until paid, bear interest from the Redemption Date at 3.25% per annum.

Section 10.7. Deposit of Redemption Price. Prior to or on any Redemption Date, the Company shall deposit with the Trustee or with a Paying Agent an amount of money sufficient to pay the Redemption Price of all the Securities to be redeemed on that Redemption Date, other than any Securities called for redemption on that date which have been converted prior to the date of such deposit, and accrued and unpaid interest, if any, on such Securities.

If any Security called for redemption is converted, any money deposited with the Trustee or with a Paying Agent or so segregated and held in trust for the redemption of such Security shall (subject to any right of the Holder of such Security or any Predecessor Security to receive interest as provided in the fourth to last paragraph of Section 2.1 hereof) be paid to the Company at the Company’s request or, if then held by the Company, shall be discharged from such trust.

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Section 10.8. Securities Redeemed in Part. Any Security which is to be redeemed only in part shall be surrendered at an office or agency of the Company designated for that purpose pursuant to Section 9.2 hereof (with, if the Company or the Trustee so requires, due endorsement by, or a written instrument of transfer in form satisfactory to the Company and the Trustee duly executed by, the Holder thereof or the Holder’s attorney duly authorized in writing), and the Company shall execute, and the Trustee shall authenticate and deliver to the Holder of such Security without service charge, a new Security or Securities of any authorized denomination as requested by such Holder in aggregate principal amount equal to and in exchange for the unredeemed portion of the principal of the Security so surrendered.

ARTICLE XI

REPURCHASE AT THE OPTION OF A HOLDER

UPON A FUNDAMENTAL CHANGE

Section 11.1. Repurchase Right. In the event that a Fundamental Change shall occur, each Holder shall have the right (the “Repurchase Right”), at the Holder’s option, but subject to the provisions of Section 11.2 hereof, to require the Company to repurchase, and upon the exercise of such right the Company shall repurchase, all of such Holder’s Securities not theretofore called for redemption, or any portion of the principal amount thereof that is equal to $1,000 or any integral multiple thereof (provided that no single Security may be repurchased in part unless the portion of the principal amount of such Security to be Outstanding after such repurchase is equal to $1,000 or integral multiples thereof), on the date (the “Repurchase Date”) that is 45 days after the date of the Company Notice (as defined in Section 11.3) at a purchase price equal to 100% of the principal amount of the Securities to be repurchased (the “Repurchase Price”), plus interest accrued and unpaid to, but excluding, the Repurchase Date; provided, however, that installments of interest on Securities whose Stated Maturity is prior to or on the Repurchase Date shall be payable to the Holders of such Securities, or one or more Predecessor Securities, registered as such on the relevant Record Date according to their terms and the provisions of Section 2.1 hereof.

Whenever in this Indenture (including Sections 2.2, 4.1(a) and 4.7 hereof) or Exhibit A annexed hereto there is a reference, in any context, to the principal of any Security as of any time, such reference shall be deemed to include reference to the Repurchase Price payable in respect to such Security to the extent that such Repurchase Price is, was or would be so payable at such time, and express mention of the Repurchase Price in any provision of this Indenture shall not be construed as excluding the Repurchase Price in those provisions of this Indenture when such express mention is not made.

Section 11.2. [Reserved]

Section 11.3. Notices; Method of Exercising Repurchase Right, Etc. (a) Unless the Company shall have theretofore called for redemption all of the Outstanding Securities, prior to or on the 30th day after the occurrence of a Fundamental Change, the Company, or, at the written request and expense of the Company prior to or on the 30th day after such occurrence, the Trustee, shall give to all Holders of Securities notice, in the manner provided in Section 14.2 hereof, of the occurrence of the Fundamental Change and of the Repurchase Right set forth

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herein arising as a result thereof (the “Company Notice”). The Company shall also deliver a copy of such notice of a Repurchase Right to the Trustee. Each notice of a Repurchase Right shall state:

(i) the Repurchase Date;

(ii) the date by which the Repurchase Right must be exercised;

(iii) the Repurchase Price and accrued and unpaid interest, if any;

(iv) a description of the procedure which a Holder must follow to exercise a Repurchase Right, and the place or places where such Securities, are to be surrendered for payment of the Repurchase Price and accrued and unpaid interest, if any;

(v) that on the Repurchase Date the Repurchase Price and accrued and unpaid interest, if any, will become due and payable upon each such Security designated by the Holder to be repurchased, and that interest thereon shall cease to accrue on and after said date;

(vi) the Conversion Rate then in effect, the place where such Securities may be surrendered for conversion and that Securities as to which a Fundamental Change Repurchase Notice has been given may be converted pursuant to Article XII of this Indenture only to the extent that the Fundamental Change Repurchase Notice has been withdrawn in accordance with the terms of this Indenture;

(vii) the place or places where such Securities, together with the Fundamental Change Repurchase Notice included in Exhibit A annexed hereto, are to be delivered for payment of the Repurchase Price and accrued and unpaid interest, if any; and

(viii) whether a Make-Whole Premium shall be payable by the Company upon conversion.

No failure of the Company to give the foregoing notices or defect therein shall limit any Holder’s right to exercise a Repurchase Right or affect the validity of the proceedings for the repurchase of Securities.

If any of the foregoing provisions or other provisions of this Article XI are inconsistent with applicable law, such law shall govern.

(b) To exercise a Repurchase Right in respect of a Security, a Holder shall deliver a written notice of the exercise of such right (a “Fundamental Change Repurchase Notice”) to the Trustee prior to the Repurchase Date. Such Fundamental Change Repurchase Notice shall state:

(i) the certificate number (if such Security is not a Global Security) of the Security which the Holder will deliver to be purchased;

(ii) the portion of the principal amount of the Security which the Holder will deliver to be purchased in integral multiples of $1,000; and

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(iii) that such Security shall be purchased as of the Repurchase Date pursuant to the terms and conditions specified in the Securities and in this Indenture.

The delivery of a Security for which a Fundamental Change Repurchase Notice has been timely delivered to the Trustee and not validly withdrawn (together with all necessary endorsements) at the office of the Trustee shall be a condition to the receipt by the Holder of the Repurchase Price therefor.

Anything herein to the contrary notwithstanding, in the case of Global Securities, any Fundamental Change Repurchase Notice may be delivered or withdrawn and such Securities may be surrendered or delivered for purchase in accordance with the Applicable Procedures as in effect from time to time.

(c) In the event a Repurchase Right shall be exercised in accordance with the terms hereof (unless a Fundamental Change Repurchase Notice is withdrawn as specified in Section 11.3(f)), the Company shall pay or cause to be paid to the Trustee the Repurchase Price in cash, as provided above, for payment to the Holder on the Repurchase Date, together with accrued and unpaid interest to the Repurchase Date payable in cash with respect to the Securities as to which the Repurchase Right has been exercised; provided, however, that installments of interest that mature prior to or on the Repurchase Date shall be payable in cash to the Holders of such Securities, or one or more Predecessor Securities, registered as such at the close of business on the relevant Regular Record Date.

(d) If any Security (or portion thereof) surrendered for repurchase shall not be so paid on the Repurchase Date, the principal amount of such Security (or portion thereof, as the case may be) shall, until paid, bear interest to the extent permitted by applicable law from the Repurchase Date at the rate of interest on the Security, and each Security shall, to the extent the Fundamental Change Repurchase Notice in respect thereof is withdrawn in accordance with the provisions of Section 11.3(f), remain convertible into Common Stock until the principal of such Security (or portion thereof, as the case may be) shall have been paid or duly provided for.

(e) Any Security which is to be repurchased only in part shall be surrendered to the Trustee (with, if the Company or the Trustee so requires, due endorsement by, or a written instrument of transfer in form satisfactory to the Company and the Trustee duly executed by the Holder thereof or his attorney duly authorized in writing), and the Company shall execute, and the Trustee shall authenticate and make available for delivery to the Holder of such Security without service charge, a new Security or Securities, containing identical terms and conditions, each in an authorized denomination in aggregate principal amount equal to and in exchange for the unrepurchased portion of the principal of the Security so surrendered.

(f) A Fundamental Change Repurchase Notice may be withdrawn by means of a written notice (which may be delivered by mail, overnight courier, hand delivery, facsimile transmission or in any other written form and, in the case of Global Securities, may be delivered electronically or by other means in accordance with the Applicable Procedures) of withdrawal delivered by the Holder to the Trustee at any time prior to the close of business on the Business Day immediately prior to the Repurchase Date, specifying (i) the principal amount of the Security or portion thereof (which must be a principal amount of $1,000 or an integral multiple

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of $1,000 in excess thereof) with respect to which such notice of withdrawal is being submitted, (ii) if Physical Securities have been issued, the certificate number of the Security being withdrawn in whole or in withdrawable part (or if the Securities are not certificated, such written notice must comply with the procedures of the Depositary) and (iii) the portion of the principal amount of the Security that will remain subject to the Fundamental Change Repurchase Notice, which portion must be a principal amount of $1,000 or an integral multiple thereof.

(g) All Securities delivered for repurchase shall be delivered to the Trustee to be canceled at the direction of the Trustee, which shall dispose of the same as provided in Section 2.15 hereof.

ARTICLE XII

CONVERSION OF SECURITIES

Section 12.1. Conversion Right and Conversion Rate. Subject to and upon compliance with the provisions of this Article, at the option of the Holder thereof, any Security or any portion of the principal amount thereof which is $1,000 or an integral multiple of $1,000 may be converted at the principal amount thereof, or of such portion thereof, into duly authorized, fully paid and nonassessable shares of Common Stock, at the Conversion Rate, determined as hereinafter provided, in effect at the time of conversion. Such conversion right may be exercised at any time prior to the Stated Maturity of the principal of the Securities.

In case a Security or portion thereof is called for redemption, such conversion right in respect of the Security or the portion so called, shall expire at the close of business on the Business Day next preceding the Redemption Date, unless the Company defaults in making the payment due upon redemption. Securities in respect of which a Fundamental Change Repurchase Notice has been given by the Holder thereof may not be converted into shares of Common Stock pursuant to this Article XII unless such Fundamental Change Repurchase Notice has first been validly withdrawn in accordance with Section 11.3(f) with respect to the Securities to be converted.

The rate at which shares of Common Stock shall be delivered upon conversion (the “Conversion Rate”) shall be initially equal to 46.4727 shares of Common Stock per $1,000 principal amount of Securities. The Conversion Rate shall be adjusted in certain instances as provided in paragraphs (a), (b), (c), (d), (e), (f), (h) and (i) of Section 12.4 hereof.

Section 12.2. Exercise of Conversion Right. To exercise the conversion right in respect of a Physical Security, the Holder must: (a) complete the conversion notice on the reverse of such Security (or a facsimile thereof); (b) deliver such completed conversion notice and such Security to be converted to the office of the Conversion Agent; (c) furnish appropriate endorsement and transfer documents; (d) pay all funds required, if any, relating to interest on such Security to be converted to which such Holder is not entitled; and (e) pay all taxes or duties, if any. To exercise the conversion right in respect of a beneficial interest in a Global Security, the holder of such beneficial interest must comply with the clauses (c), (d) and (e) of the preceding sentence and deliver to the Depositary the appropriate instruction form for conversion pursuant to the Depositary’s conversion program in accordance with the Applicable Procedures.

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Securities surrendered for conversion during the period from the close of business on any Regular Record Date to the opening of business on the next succeeding Interest Payment Date (except in the case of any Security whose Maturity is prior to such Interest Payment Date) shall be accompanied by payment in New York Clearing House funds or other funds acceptable to the Company of an amount equal to the interest to be received on such Interest Payment Date on the principal amount of Securities being surrendered for conversion; provided, however, that no such payment need be made (a) if a Repurchase Date following a Fundamental Change occurs on a date that is after a Regular Record Date and on or prior to the next Interest Payment Date, (b) only to the extent of overdue interest, if any overdue interest exists at the time of conversion with respect to such Security, (c) if a Redemption Date for the Securities occurs on a date that is after a Regular Record Date and on or prior to the next Interest Payment Date, or (d) the Securities are surrendered for conversion on or after September 13, 2012.

Securities shall be deemed to have been converted immediately prior to the close of business on the day of surrender of such Securities for conversion in accordance with the foregoing provisions, and at such time the rights of the Holders of such Securities as Holders shall cease, and the Person or Persons entitled to receive the Common Stock issuable upon conversion shall be treated for all purposes as the record holder or holders of such Common Stock at such time. As promptly as practicable on or after the conversion date, the Company shall cause to be issued and delivered to such Conversion Agent a certificate or certificates for the number of full shares of Common Stock issuable upon conversion, together with payment in lieu of any fraction of a share as provided in Section 12.3 hereof.

In the case of any Security which is converted in part only, upon such conversion the Company shall execute and the Trustee shall authenticate and deliver to the Holder thereof, at the expense of the Company, a new Security or Securities of authorized denominations in aggregate principal amount equal to the unconverted portion of the principal amount of such Securities.

If shares of Common Stock to be issued upon conversion of a Restricted Security, or Securities to be issued upon conversion of a Restricted Security in part only, are to be registered in a name other than that of the Holder of such Restricted Security, such Holder must deliver to the Conversion Agent a certificate in substantially the form set forth in the form of Security set forth in Exhibit A annexed hereto, dated the date of surrender of such Restricted Security and signed by such Holder, as to compliance with the restrictions on transfer applicable to such Restricted Security. Neither the Trustee nor any Conversion Agent, Registrar or Transfer Agent shall be required to register in a name other than that of the Holder shares of Common Stock or Securities issued upon conversion of any such Restricted Security not so accompanied by a properly completed certificate.

The Company hereby initially appoints the Trustee as the Conversion Agent.

Section 12.3. Fractions of Shares. No fractional shares of Common Stock shall be issued upon conversion of any Security or Securities. If more than one Security shall be surrendered for conversion at one time by the same Holder, the number of full shares which shall be issued upon conversion thereof shall be computed on the basis of the aggregate principal amount of the Securities (or specified portions thereof) so surrendered. Instead of any fractional share of Common Stock which would otherwise be issued upon conversion of any Security or Securities

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(or specified portions thereof), the Company shall pay a cash adjustment in respect of such fraction (calculated to the nearest one-100th of a share) in an amount equal to the same fraction of the Closing Price of the Common Stock as of the Trading Day preceding the date of conversion.

Section 12.4. Adjustment of Conversion Rate. The Conversion Rate shall be subject to adjustment, calculated by the Company, from time to time as follows:

(a) In case the Company shall hereafter pay a dividend or make a distribution to all holders of the outstanding Common Stock in shares of Common Stock, the Conversion Rate in effect at the opening of business on the date next following the date fixed for the determination of stockholders entitled to receive such dividend or other distribution shall be increased by multiplying such Conversion Rate by a fraction:

(i) the numerator of which shall be the number of shares of Common Stock outstanding at the close of business on the Record Date (as defined in Section 12.4(g)) fixed for such determination and the total number of shares constituting such dividend or other distribution, and

(ii) the denominator of which shall be the number of shares of Common Stock outstanding at the close of business on the Record Date fixed for such determination.

Such increase shall become effective immediately after the opening of business on the day next following the Record Date. If any dividend or distribution of the type described in this Section 12.4(a) is declared but not so paid or made, the Conversion Rate shall again be adjusted to the Conversion Rate which would then be in effect if such dividend or distribution had not been declared.

(b) In case the outstanding shares of Common Stock shall be subdivided into a greater number of shares of Common Stock, the Conversion Rate in effect at the opening of business on the day next following the day upon which such subdivision becomes effective shall be proportionately increased, and conversely, in case outstanding shares of Common Stock shall be combined into a smaller number of shares of Common Stock, the Conversion Rate in effect at the opening of business on the day next following the day upon which such combination becomes effective shall be proportionately reduced, such increase or reduction, as the case may be, to become effective immediately after the opening of business on the day following the day upon which such subdivision or combination becomes effective.

(c) In case the Company shall issue rights or warrants to all holders of its outstanding shares of Common Stock entitling them for a period of not more than 45 days to subscribe for or purchase shares of Common Stock at a price per share less than the Current Market Price (as defined in Section 12.4(g)) on the Record Date fixed for the determination of stockholders entitled to receive such rights or warrants, the Conversion Rate shall be increased so that the same shall equal the rate determined by multiplying

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the Conversion Rate in effect at the opening of business on the date after such Record Date by a fraction:

(i) the numerator of which shall be the number of shares of Common Stock outstanding at the close of business on the Record Date plus the total number of additional shares of Common Stock so offered for subscription or purchase, and

(ii) the denominator of which shall be the number of shares of Common Stock outstanding on the close of business on the Record Date plus the number of shares which the aggregate offering price of the total number of shares so offered for subscription or purchase would purchase at such Current Market Price.

Such adjustment shall become effective immediately after the opening of business on the day next following the Record Date fixed for determination of stockholders entitled to receive such rights or warrants. To the extent that shares of Common Stock are not delivered pursuant to such rights or warrants, upon the expiration or termination of such rights or warrants the Conversion Rate shall be readjusted to the Conversion Rate which would then be in effect had the adjustments made upon the issuance of such rights or warrants been made on the basis of the delivery of only the number of shares of Common Stock actually delivered. In the event that such rights or warrants are not so issued, the Conversion Rate shall again be adjusted to be the Conversion Rate which would then be in effect if such date fixed for the determination of stockholders entitled to receive such rights or warrants had not been fixed. In determining whether any rights or warrants entitle the holders to subscribe for or purchase shares of Common Stock at less than such Current Market Price, and in determining the aggregate offering price of such shares of Common Stock, there shall be taken into account any consideration received for such rights or warrants, the value of such consideration, if other than cash, to be determined by the Board of Directors.

(d) In case the Company shall, by dividend or otherwise, distribute to all holders of its Common Stock shares of any class of capital stock of the Company (other than any dividends or distributions to which Section 12.4(a) applies) or evidences of its indebtedness, cash or other assets, including securities, but excluding (1) any rights or warrants referred to in Section 12.4(c), (2) any stock, securities or other property or assets (including cash) distributed in connection with a reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance to which Section 12.11 hereof applies and (3) dividends and distributions paid exclusively in cash, then, in each such case, subject to the second succeeding paragraph of this Section 12.4(d), the Conversion Rate shall be increased so that the same shall be equal to the rate determined by multiplying the Conversion Rate in effect immediately prior to the close of business on the Record Date (as defined in Section 12.4(g)) with respect to such distribution by a fraction:

(i) the numerator of which shall be the Current Market Price (determined as provided in Section 12.4(g)) on such date, and

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(ii) the denominator of which shall be such Current Market Price on such date less the fair market value (as determined by the Board of Directors in accordance with the provisions of Section 12.4(g)(ii), whose determination shall be conclusive and set forth in a Board Resolution) on such date of the portion of the shares of capital stock, evidences of indebtedness, cash or other assets, including securities, so distributed applicable to one share of Common Stock (determined on the basis of the number of shares of the Common Stock outstanding on the Record Date).

Such increase shall become effective immediately prior to the opening of business on the day next following the Record Date. However, in the event that the then fair market value (as so determined) of the portion of the securities so distributed applicable to one share of Common Stock is equal to or greater than the Current Market Price on the Record Date, in lieu of the foregoing adjustment, adequate provision shall be made so that each Holder shall have the right to receive upon conversion of a Security (or any portion thereof) the amount of shares of capital stock, evidences of indebtedness, cash or other assets, including securities, such Holder would have received had such Holder converted such Security (or portion thereof) immediately prior to such Record Date. In the event that such dividend or distribution is not so paid or made, the Conversion Rate shall again be adjusted to be the Conversion Rate which would then be in effect if such dividend or distribution had not been declared.

If the Board of Directors determines the fair market value of any distribution for purposes of this Section 12.4(d) by reference to the actual or when issued trading market for any securities comprising all or part of such distribution, it must in doing so consider the prices in such market over the same period (the “Reference Period”) used in computing the Current Market Price pursuant to Section 12.4(g) to the extent possible, unless the Board of Directors in a Board Resolution determines in good faith that determining the fair market value during the Reference Period would not be in the best interest of the Holder.

Notwithstanding the foregoing, if the securities distributed by the Company to all holders of its Common Stock consist of capital stock of, or similar equity interests in, a Subsidiary or other business unit of the Company (“Spinoff Securities”), the Conversion Rate shall be adjusted, unless Holders participate in such distribution by receiving, in respect of each $1,000 principal amount of Securities, the Spinoff Securities that a holder of a number of shares of Common Stock equal to the Conversion Rate would receive, so that the same shall be equal to the rate determined by multiplying the Conversion Rate in effect on the record date fixed for the determination of shareholders entitled to receive such distribution by a fraction,

(i) the numerator of which shall be the sum of (A) the average of the Closing Prices of one share of Common Stock over the ten consecutive Trading Day period (the “Spinoff Valuation Period”) commencing on and including the fifth Trading Day after the date on which ex-dividend trading commences for such distribution on the Nasdaq National Market or such other U.S. national or regional exchange or market on which the Common Stock is then listed or quoted

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and (B) the average of the Closing Prices over the Spinoff Valuation Period of the Spinoff Securities multiplied by the number of Spinoff Securities distributed in respect of one share of Common Stock, and

(ii) the denominator of which shall be the average of the Closing Prices of one share of Common Stock over the Spinoff Valuation Period,

such adjustment to become effective immediately prior to the opening of business on the fifteenth Trading Day after the date on which ex-dividend trading commences; provided, however, that the Company may in lieu of the foregoing adjustment elect to make adequate provision so that each Holder of a Security shall have the right to receive upon conversion thereof, an amount of such Spinoff Securities equal to the amount of Spinoff Securities distributed in respect of one share of Common Stock multiplied by the Conversion Rate in effect as of the record date for the distribution of such Spinoff Securities.

Rights or warrants distributed by the Company to all holders of Common Stock entitling the holders thereof to subscribe for or purchase shares of the Company’s capital stock (either initially or under certain circumstances), which rights or warrants, until the occurrence of a specified event or events (“Trigger Event”):

(i) are deemed to be transferred with such shares of Common Stock;

(ii) are not exercisable; and

(iii) are also issued in respect of future issuances of Common Stock,

shall be deemed not to have been distributed for purposes of this Section 12.4(d) (and no adjustment to the Conversion Rate under this Section 12.4(d) will be required) until the occurrence of the earliest Trigger Event. If such right or warrant is subject to subsequent events, upon the occurrence of which such right or warrant shall become exercisable to purchase different securities, evidences of indebtedness or other assets or entitle the holder to purchase a different number or amount of the foregoing or to purchase any of the foregoing at a different purchase price, then the occurrence of each such event shall be deemed to be the date of issuance and record date with respect to a new right or warrant (and a termination or expiration of the existing right or warrant without exercise by the holder thereof). In addition, in the event of any distribution (or deemed distribution) of rights or warrants, or any Trigger Event or other event (of the type described in the preceding sentence) with respect thereto, that resulted in an adjustment to the Conversion Rate under this Section 12.4(d):

(i) in the case of any such rights or warrants which shall all have been redeemed or repurchased without exercise by any holders thereof, the Conversion Rate shall be readjusted upon such final redemption or repurchase to give effect to such distribution or Trigger Event, as the case may be, as though it were a cash distribution, equal to the per share redemption or repurchase price received by a holder of Common Stock with respect to such rights or warrant (assuming such holder had retained such rights or warrants), made to all holders of Common Stock as of the date of such redemption or repurchase, and

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(ii) in the case of such rights or warrants all of which shall have expired or been terminated without exercise, the Conversion Rate shall be readjusted as if such rights and warrants had never been issued.

For purposes of this Section 12.4(d) and Sections 12.4(a), 12.4(b) and 12.4(c), any dividend or distribution to which this Section 12.4(d) is applicable that also includes shares of Common Stock, a subdivision or combination of Common Stock to which Section 12.4(b) applies, or rights or warrants to subscribe for or purchase shares of Common Stock to which Section 12.4(c) applies (or any combination thereof), shall be deemed instead to be:

(i) a dividend or distribution of the evidences of indebtedness, assets, shares of capital stock, rights or warrants other than such shares of Common Stock, such subdivision or combination or such rights or warrants to which Sections 12.4(a), 12.4(b) and 12.4(c) apply, respectively (and any Conversion Rate increase required by this Section 12.4(d) with respect to such dividend or distribution shall then be made), immediately followed by

(ii) a dividend or distribution of such shares of Common Stock, such subdivision or combination or such rights or warrants (and any further Conversion Rate increase required by Sections 12.4(a), 12.4(b) and 12.4(c) with respect to such dividend or distribution shall then be made), except:

(A) the Record Date of such dividend or distribution shall be substituted as (x) “the date fixed for the determination of stockholders entitled to receive such dividend or other distribution,” “Record Date fixed for such determination” and “Record Date” within the meaning of Section 12.4(a), (y) “the day upon which such subdivision becomes effective” and “the day upon which such combination becomes effective” within the meaning of Section 12.4(b), and (z) as “the Record Date fixed for the determination of stockholders entitled to receive such rights or warrants,” “the Record Date fixed for the determination of the stockholders entitled to receive such rights or warrants” and such “Record Date” within the meaning of Section 12.4(c), and

(B) any shares of Common Stock included in such dividend or distribution shall not be deemed “outstanding at the close of business on the date fixed for such determination” within the meaning of Section 12.4(a) and any reduction or increase in the number of shares of Common Stock resulting from such subdivision or combination shall be disregarded in connection with such dividend or distribution.

(e) In case the Company shall pay a dividend or distribution to all holders of its Common Stock consisting exclusively of cash (excluding any cash that is distributed

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upon a Business Combination or as part of a distribution referred to in Section 12.4(d) hereof), then and in each such case, immediately after the close of business on such date, the Conversion Rate shall be increased so that the same shall equal the rate determined by multiplying the Conversion Rate in effect immediately prior to the close of business on such Record Date by a fraction:

(i) the numerator of which shall be equal to the Current Market Price on the Record Date, and

(ii) the denominator of which shall be equal to the Current Market Price on such date less an amount equal to the quotient of (x) the sum of the aggregate amount of cash so distributed and (y) the number of shares of Common Stock outstanding on the Record Date.

In the event that such dividend or distribution is not so paid or made, the Conversion Rate shall again be adjusted to be the Conversion Rate which would then be in effect if such dividend or distribution had not been declared.

(f) In case a tender offer or exchange offer made by the Company or any of its subsidiaries for all or any portion of the Common Stock shall expire and such tender offer or exchange offer (as amended upon the expiration thereof) shall require the payment to stockholders (based on the acceptance (up to any maximum specified in the terms of the tender offer) of Purchased Shares (as defined below)) of an aggregate consideration per Purchased Share having a fair market value (as determined by the Board of Directors, whose determination shall be conclusive and set forth in a Board Resolution) that exceeds the Closing Price of the Common Stock on the Trading Day next succeeding the last date (the “Expiration Time”) on which tenders or exchanges could have been made pursuant to such tender offer or exchange offer (as it may be amended), then, and in each such case, immediately prior to the opening of business on the day after the date of the Expiration Time, the Conversion Rate shall be adjusted so that the same shall equal the price determined by multiplying the Conversion Rate in effect immediately prior to close of business on the date of the Expiration Time by a fraction:

(i) the numerator of which shall be the sum of (x) the fair market value (determined as aforesaid) of the aggregate consideration payable to stockholders based on the acceptance (up to any maximum specified in the terms of the tender or exchange offer) of all shares validly tendered or exchanged and not withdrawn as of the Expiration Time (the shares deemed so accepted, up to any such maximum, being referred to as the “Purchased Shares”) and (y) the product of the number of shares of Common Stock outstanding (less any Purchased Shares) on the Expiration Time and the Closing Price of the Common Stock on the Trading Day next succeeding the Expiration Time, and

(ii) the denominator of which shall be the number of shares of Common Stock outstanding (including any tendered or exchanged shares) at the Expiration Time multiplied by the Closing Price of the Common Stock on the Trading Day next succeeding the Expiration Time.

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Such increase (if any) shall become effective as of the time that is immediately prior to the opening of business on the day following the Expiration Time. In the event that the Company is obligated to purchase shares pursuant to any such tender offer, but the Company is permanently prevented by applicable law from effecting any such purchases or all such purchases are rescinded, the Conversion Rate shall again be adjusted to be the Conversion Rate which would then be in effect if such tender offer had not been made. If the application of this Section 12.4(f) to any tender offer would result in a decrease in the Conversion Rate, no adjustment shall be made for such tender offer under this Section 12.4(f).

(g) For purposes of this Section 12.4, the following terms shall have the meanings indicated:

(i) “Current Market Price” shall mean the average of the daily Closing Prices per share of Common Stock for the ten consecutive Trading Days immediately prior to the date in question; provided, however, that if:

(A) the “ex” date (as hereinafter defined) for any event (other than the issuance or distribution requiring such computation) that requires an adjustment to the Conversion Rate pursuant to Section 12.4(a), (b), (c), (d), (e) or (f) occurs during such ten consecutive Trading Days, the Closing Price for each Trading Day prior to the “ex” date for such other event shall be adjusted by dividing such Closing Price by the same fraction by which the Conversion Rate is so required to be adjusted as a result of such other event;

(B) the “ex” date for any event (other than the issuance or distribution requiring such computation) that requires an adjustment to the Conversion Rate pursuant to Section 12.4(a), (b), (c), (d), (e) or (f) occurs on or after the “ex” date for the issuance or distribution requiring such computation and prior to the day in question, the Closing Price for each Trading Day on and after the “ex” date for such other event shall be adjusted by dividing such Closing Price by the reciprocal of the fraction by which the Conversion Rate is so required to be adjusted as a result of such other event; and

(C) the “ex” date for the issuance or distribution requiring such computation is prior to the day in question, after taking into account any adjustment required pursuant to clause (i) or (ii) of this proviso, the Closing Price for each Trading Day on or after such “ex” date shall be adjusted by adding thereto the amount of any cash and the fair market value (as determined by the Board of Directors in a manner consistent with any determination of such value for purposes of Section 12.4(d) or (f), whose determination shall be conclusive and set forth in a Board

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Resolution) of the evidences of indebtedness, shares of capital stock or assets being distributed applicable to one share of Common Stock as of the close of business on the day before such “ex” date.

For purposes of any computation under Section 12.4(f), if the “ex” date for any event (other than the tender offer that is the subject of the adjustment pursuant to Section 12.4(f)) that requires an adjustment to the Conversion Rate pursuant to Section 12.4(a), (b), (c), (d) or (e) occurs on the date of the Expiration Time for the tender or exchange offer requiring such computation or on the Trading Day next following the Expiration Time, the Closing Price for each Trading Day on and after the “ex” date for such other event shall be adjusted by dividing such Closing Price by the reciprocal of the fraction by which the Conversion Rate is so required to be adjusted as a result of such other event. For purposes of this clause (i), the term “ex” date, when used:

(A) with respect to any issuance or distribution, means the first date on which the Common Stock trades regular way on the relevant exchange or in the relevant market from which the Closing Price was obtained without the right to receive such issuance or distribution;

(B) with respect to any subdivision or combination of shares of Common Stock, means the first date on which the Common Stock trades regular way on such exchange or in such market after the time at which such subdivision or combination becomes effective, and

(C) with respect to any tender or exchange offer, means the first date on which the Common Stock trades regular way on such exchange or in such market after the Expiration Time of such offer.

Notwithstanding the foregoing, whenever successive adjustments to the Conversion Rate are called for pursuant to this Section 12.4, such adjustments shall be made to the Current Market Price as may be necessary or appropriate to effectuate the intent of this Section 12.4 and to avoid unjust or inequitable results as determined in good faith by the Board of Directors.

(ii) “fair market value” shall mean the amount which a willing buyer would pay a willing seller in an arm’s length transaction.

(iii) “Record Date” shall mean, with respect to any dividend, distribution or other transaction or event in which the holders of Common Stock have the right to receive any cash, securities or other property or in which the Common Stock (or other applicable security) is exchanged for or converted into any combination of cash, securities or other property, the date fixed for determination of stockholders entitled to receive such cash, securities or other property (whether such date is fixed by the Board of Directors or by statute, contract or otherwise).

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(h) To the extent permitted by applicable law and subject to the stockholder approval requirements of the Nasdaq National Market or such other United States securities exchange on which the Common Stock is listed, the Company may make such increase in the Conversion Rate, in addition to those required by Sections 12.4(a), (b), (c), (d), (e) or (f), as the Board of Directors considers to be advisable to avoid or diminish any income tax to holders of Common Stock or rights to purchase Common Stock resulting from any dividend or distribution of stock (or rights to acquire stock) or from any event treated as such for income tax purposes.

To the extent permitted by applicable law and subject to the stockholder approval requirements of the Nasdaq National Market or such other United States securities exchange on which the Common Stock is traded, the Company from time to time may increase the Conversion Rate by any amount for any period of time if the period is at least 20 days and the increase is irrevocable during the period and the Board of Directors determines in good faith that such increase would be in the best interests of the Company, which determination shall be conclusive and set forth in a Board Resolution. Whenever the Conversion Rate is increased pursuant to the preceding sentence, the Company shall mail to the Trustee and each Holder at the address of such Holder as it appears in the Register a notice of the increase at least 15 days prior to the date the increased Conversion Rate takes effect, and such notice shall state the increased Conversion Rate and the period during which it will be in effect.

(i) No adjustment in the Conversion Rate shall be required unless such adjustment would require an increase or decrease of at least 1% in such rate; provided, however, that any adjustments which by reason of this Section 12.4(i) are not required to be made shall be carried forward and taken into account in any subsequent adjustment; provided further, however, that a Holder who has converted Securities prior to any such subsequent adjustment shall be entitled to the benefit of all adjustments which would otherwise have been carried forward. All calculations under this Article XII shall be made by the Company and shall be made to the nearest cent or to the nearest one hundredth of a share, as the case may be. No adjustment need be made for a change in the par value or no par value of the Common Stock.

(j) In any case in which this Section 12.4 provides that an adjustment shall become effective immediately after a Record Date for an event, the Company may defer until the occurrence of such event (i) issuing to the Holder of any Security converted after such Record Date and before the occurrence of such event the additional shares of Common Stock issuable upon such conversion by reason of the adjustment required by such event over and above the Common Stock issuable upon such conversion before giving effect to such adjustment and (ii) paying to such holder any amount in cash in lieu of any fraction pursuant to Section 12.3 hereof.

(k) For purposes of this Section 12.4, the number of shares of Common Stock at any time outstanding shall not include shares held in the treasury of the Company but shall include shares issuable in respect of scrip certificates issued in lieu of fractions of shares of Common Stock. The Company will not pay any dividend or make any distribution on shares of Common Stock held in the treasury of the Company.

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(l) If the distribution date for the rights provided in the Company’s rights agreement, if any, occurs prior to the date a Security is converted, the Holder of the Security who converts such Security after the distribution date is not entitled to receive the rights that would otherwise be attached (but for the date of conversion) to the shares of Common Stock received upon such conversion; provided, however, that an adjustment shall be made to the Conversion Rate pursuant to clause 12.4(b) as if the rights were being distributed to the common stockholders of the Company immediately prior to such conversion. If such an adjustment is made and the rights are later redeemed, invalidated or terminated, then a corresponding reversing adjustment shall be made to the Conversion Rate, on an equitable basis, to take account of such event.

Section 12.5. Notice of Adjustments of Conversion Rate. Whenever the Conversion Rate is adjusted as herein provided (other than in the case of an adjustment pursuant to the second paragraph of Section 12.4(h) for which the notice required by such paragraph has been provided), the Company shall promptly file with the Trustee and any Conversion Agent other than the Trustee an Officers’ Certificate setting forth the adjusted Conversion Rate and showing in reasonable detail the facts upon which such adjustment is based. Promptly after delivery of such Officers’ Certificate, the Company shall prepare a notice stating that the Conversion Rate has been adjusted and setting forth the adjusted Conversion Rate and the date on which each adjustment becomes effective, and shall mail such notice to each Holder at the address of such Holder as it appears in the Register within 20 days of the effective date of such adjustment. Failure to deliver such notice shall not effect the legality or validity of any such adjustment.

Section 12.6. Notice Prior to Certain Actions. In case at any time after the date hereof:

(1) the Company shall declare a dividend (or any other distribution) on its Common Stock payable otherwise than in cash out of its capital surplus or its consolidated retained earnings;

(2) the Company shall authorize the granting to the holders of its Common Stock of rights or warrants to subscribe for or purchase any shares of capital stock of any class (or of securities convertible into shares of capital stock of any class) or of any other rights;

(3) there shall occur any reclassification of the Common Stock of the Company (other than a subdivision or combination of its outstanding Common Stock, a change in par value, a change from par value to no par value or a change from no par value to par value), or any merger, consolidation, statutory share exchange or combination to which the Company is a party and for which approval of any shareholders of the Company is required, or the sale, transfer or conveyance of all or substantially all of the assets of the Company; or

(4) there shall occur the voluntary or involuntary dissolution, liquidation or winding up of the Company;

the Company shall cause to be filed at each office or agency maintained for the purpose of conversion of securities pursuant to Section 9.2 hereof, and shall cause to be provided to the

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Trustee and all Holders in accordance with Section 14.2 hereof, at least 20 days (or 10 days in any case specified in clause (1) or (2) above) prior to the applicable record or effective date hereinafter specified, a notice stating:

(a) the date on which a record is to be taken for the purpose of such dividend, distribution, rights or warrants, or, if a record is not to be taken, the date as of which the holders of Common Stock of record to be entitled to such dividend, distribution, rights or warrants are to be determined, or

(b) the date on which such reclassification, merger, consolidation, statutory share exchange, combination, sale, transfer, conveyance, dissolution, liquidation or winding up is expected to become effective, and the date as of which it is expected that holders of Common Stock of record shall be entitled to exchange their shares of Common Stock for securities, cash or other property deliverable upon such reclassification, merger, consolidation, statutory share exchange, sale, transfer, dissolution, liquidation or winding up.

Neither the failure to give such notice nor any defect therein shall affect the legality or validity of the proceedings or actions described in clauses (1) through (4) of this Section 12.6.

Section 12.7. Company to Reserve Common Stock. The Company shall at all times use its best efforts to reserve and keep available, free from preemptive rights, out of its authorized but unissued Common Stock, for the purpose of effecting the conversion of Securities, the full number of shares of fully paid and nonassessable Common Stock then issuable upon the conversion of all Outstanding Securities, including pursuant to any Make-Whole Premium.

The Company further covenants that, if at any time the Common Stock shall be listed on the Nasdaq National Market or any national securities exchange or other automated quotation system, the Company will, if permitted by the rules of such market, exchange or automated quotation system, list and keep listed, so long as the Common Stock shall be so listed on such market, exchange or automated quotation system, all Common Stock issuable upon conversion of the Securities; provided that if the rules of such market, exchange or automated quotation system permit the Company to defer the listing of such Common Stock until the first conversion of the Securities into Common Stock in accordance with the provisions of this Indenture, the Company covenants to list such Common Stock issuable upon conversion of the Securities in accordance with the requirements of such market, exchange or automated quotation system at such time.

Section 12.8. Taxes on Conversions. Except as provided in the next sentence, the Company will pay any and all taxes (other than taxes on income) and duties that may be payable in respect of the issue or delivery of shares of Common Stock on conversion of Securities pursuant hereto. A Holder delivering a Security for conversion shall be liable for and will be required to pay any tax or duty which may be payable in respect of any transfer involved in the issue and delivery of shares of Common Stock in a name other than that of the Holder of the Security or Securities to be converted, and no such issue or delivery shall be made unless the Person requesting such issue has paid to the Company the amount of any such tax or duty, or has established to the satisfaction of the Company that such tax or duty has been paid.

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Section 12.9. Covenant as to Common Stock. The Company covenants that all shares of Common Stock which may be issued upon conversion of Securities will upon issue be fully paid and nonassessable and, except as provided in Section 12.8, the Company will pay all taxes, liens and charges with respect to the issue thereof.

Section 12.10. Cancellation of Converted Securities. All Securities delivered for conversion shall be delivered to the Trustee to be canceled by or at the direction of the Trustee, which shall dispose of the same as provided in Section 2.9.

Section 12.11. Effect of Recapitalization, Reclassification, Consolidation, Merger or Sale. If any of following events occur (each, a “Business Combination”), namely:

(a) any recapitalization, reclassification or change of the Common Stock, other than changes resulting from a subdivision or a combination,

(b) a consolidation, merger or combination involving the Company, or

(c) a sale, conveyance or lease to another corporation of all or substantially all of the property and assets of the Company, or

(d) any statutory share exchange,

in each case as a result of which holders of Common Stock are entitled to receive stock, other securities, other property or assets (including cash or any combination thereof) with respect to or in exchange for Common Stock, the Company or the successor or purchasing corporation, as the case may be, shall execute with the Trustee a supplemental indenture (which shall comply with the TIA as in force at the date of execution of such supplemental indenture if such supplemental indenture is then required to so comply) providing that the Holders of the Securities then outstanding will be entitled thereafter to convert such Securities into the kind and amount of shares of stock, other securities or other property or assets (including cash or any combination thereof) which they would have owned or been entitled to receive upon such Business Combination had such Securities been converted into Common Stock immediately prior to such Business Combination. In the event holders of Common Stock have the opportunity to elect the form of consideration to be received in such Business Combination, the Company shall make adequate provision whereby the Holders of the Securities shall have a reasonable opportunity to determine the form of consideration into which all of the Securities, treated as a single class, shall be convertible from and after the effective date of such Business Combination. Such determination shall be (i) based on the weighted average of elections made by Holders of the Securities who participate in such determination, (ii) subject to any limitations to which all of the holders of the Common Stock are subject, such as pro-rata reductions applicable to any portion of the consideration payable in such Business Combination and (iii) conducted in such a manner as to be completed by the date which is the earliest of (a) the deadline for elections to be made by stockholders of the Company, and (b) two Trading Days prior to the anticipated effective date of the Business Combination. The Company shall provide notice of the opportunity to determine the form of such consideration, as well as notice of the determination made by Holders of the Securities (and the weighted average of elections), by issuing a press release and providing a copy of such notice to the Trustee. In the event the effective date of the Business Combination is

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delayed beyond the initially anticipated effective date, Holders of the Securities shall be given the opportunity to make subsequent similar determinations in regard to such delayed effective date. Such supplemental indenture shall provide for adjustments which shall be as nearly equivalent as may be practicable to the adjustments provided for in this Article XII. If, in the case of any such Business Combination, the stock or other securities and assets receivable thereupon by a holder of shares of Common Stock includes shares of stock or other securities and assets of a corporation other than the successor or purchasing corporation, as the case may be, in such Business Combination, then such supplemental indenture shall also be executed by such other corporation and shall contain such additional provisions to protect the interests of the Holders of the Securities as the Board of Directors shall reasonably consider necessary by reason of the foregoing, including to the extent practicable the provisions providing for the Repurchase Rights set forth in Article XI hereof.

The Company shall cause notice of the execution of such supplemental indenture to be mailed to each Holder, at the address of such Holder as it appears on the Register, within 20 days after execution thereof. Failure to deliver such notice shall not affect the legality or validity of such supplemental indenture.

The above provisions of this Section shall similarly apply to successive Business Combinations.

The Company shall not become a party to any Business Combination unless its terms are consistent with the provisions of this Section 12.11.

None of the provisions of this Section 12.11 shall affect the right of a Holder of Securities to convert its Securities into Common Stock prior to the effective date of a Business Combination.

If this Section 12.11 applies to any event or occurrence, Section 12.4 hereof shall not apply.

Section 12.12. Responsibility of Trustee for Conversion Provisions. The Trustee, subject to the provisions of Section 5.1 hereof, and any Conversion Agent shall not at any time be under any duty or responsibility to any Holder of Securities to determine whether any facts exist which may require any adjustment of the Conversion Rate, or with respect to the nature or intent of any such adjustments when made, or with respect to the method employed, or herein or in any supplemental indenture provided to be employed, in making the same. Neither the Trustee, subject to the provisions of Section 5.1 hereof, nor any Conversion Agent shall be accountable with respect to the validity or value (of the kind or amount) of any Common Stock, or of any other securities or property, which may at any time be issued or delivered upon the conversion of any Security; and it or they do not make any representation with respect thereto. Neither the Trustee, subject to the provisions of Section 5.1 hereof, nor any Conversion Agent shall be responsible for any failure of the Company to make any cash payment or to issue, transfer or deliver any shares of stock or share certificates or other securities or property upon the surrender of any Security for the purpose of conversion; and the Trustee, subject to the provisions of Section 5.1 hereof, and any Conversion Agent shall not be responsible or liable for any failure of the Company to comply with any of the covenants of the Company contained in this Article.

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Section 12.13. Make-Whole Premium.

(a) If a Fundamental Change Effective Date occurs at any time prior to September 28, 2012, Holders who convert Securities in connection with a Fundamental Change shall, subject to this Section 12.13, be entitled to receive a “Make-Whole Premium” consisting of an increase in the Conversion Rate. The Make-Whole Premium, if any, shall be calculated by the Company and paid for in shares of Common Stock or in any other consideration into which the Securities are then convertible. The number of additional shares of Common Stock by which the Conversion Rate shall increase shall be determined by reference to the table below and shall equal the number of shares of Common Stock for the applicable Fundamental Change Effective Date and Stock Price of such Fundamental Change. If the applicable Fundamental Change Effective Date and/or Stock Price is not set forth in the table: (i) if the applicable Fundamental Change Effective Date and/or Stock Price is between two Fundamental Change Effective Dates or Stock Prices, as the case may be, set forth in the table, the Make-Whole Premium shall be determined by a straight-line interpolation between the Make-Whole Premiums for the two Fundamental Change Effective Dates and/or Stock Prices, as the case may be, set forth in the table based on a 365-day year, (ii) if the Stock Price on the Fundamental Change Effective Date exceeds $100.00 a share, subject to adjustment as set forth herein, no Make-Whole Premium shall be paid, and (iii) if the Stock Price on the Fundamental Change Effective Date is less than $16.24 a share, subject to adjustment as set forth herein, no Make-Whole Premium shall be paid.

	Effective Date
Stock Price on Effective Date	September 28, 2005	September 28, 2006	September 28, 2007	September 28, 2008	September 28, 2009	September 28, 2010	September 28, 2011	September 28, 2012
$16.24	15.1036	15.1036	15.1036	15.1036	15.1036	15.1036	15.1036	0.0000
17.50	12.4083	12.3807	12.4380	12.7587	13.0516	13.0894	12.4445	0.0000
20.00	9.1204	8.8922	8.6675	8.7282	8.8556	8.7233	7.8277	0.0000
22.50	6.7541	6.4015	5.9848	5.8038	5.8441	5.6622	4.7827	0.0000
25.00	4.9812	4.5816	4.0483	3.6257	3.6300	3.4592	2.7418	0.0000
27.50	3.0564	3.1762	2.6314	1.9814	1.9825	1.8529	1.3586	0.0000
30.00	2.8020	1.9468	1.4888	0.7687	0.7603	0.7058	0.4442	0.0000
32.50	2.5882	1.7986	0.9357	0.0000	0.0000	0.0000	0.0000	0.0000
35.00	2.4045	1.6711	0.8689	0.0000	0.0000	0.0000	0.0000	0.0000
37.50	2.2463	1.5603	0.8109	0.0000	0.0000	0.0000	0.0000	0.0000
40.00	2.1031	1.4637	0.7605	0.0000	0.0000	0.0000	0.0000	0.0000
42.50	1.9776	1.3779	0.7157	0.0000	0.0000	0.0000	0.0000	0.0000
45.00	1.8678	1.3017	0.6761	0.0000	0.0000	0.0000	0.0000	0.0000
47.50	1.7696	1.2334	0.6405	0.0000	0.0000	0.0000	0.0000	0.0000
50.00	1.6823	1.1716	0.6084	0.0000	0.0000	0.0000	0.0000	0.0000
60.00	1.4077	0.9784	0.5075	0.0000	0.0000	0.0000	0.0000	0.0000
70.00	1.2084	0.8425	0.4370	0.0000	0.0000	0.0000	0.0000	0.0000
80.00	1.0629	0.7440	0.3888	0.0000	0.0000	0.0000	0.0000	0.0000
90.00	0.9423	0.6603	0.3478	0.0000	0.0000	0.0000	0.0000	0.0000
100.00	0.8499	0.5978	0.3140	0.0000	0.0000	0.0000	0.0000	0.0000

The Stock Prices set forth in the table above shall be adjusted as of any date on which the Conversion Rate of the Securities is adjusted by multiplying each such Stock Price in effect immediately prior to such adjustment by a fraction, the numerator of which shall be the Conversion Rate in effect immediately prior to the adjustment giving rise to the Stock Price adjustment and the denominator of which shall be the Conversion Rate as so adjusted. The number of additional shares set forth in the table above shall be adjusted in the same manner as the Conversion Rate as set forth in Section 12.4 hereof.

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Delivery of the payment of the Make-Whole Premium shall be upon the later of (x) the settlement date of the conversion of Securities by the Holder and (y) promptly following the Fundamental Change Effective Date.

(b) A conversion of Securities by a Holder will be deemed for the purposes of this Section 12.13 to be “in connection with” a Fundamental Change if the conversion notice delivered by the Holder pursuant to Section 12.2 hereof is received by a Conversion Agent (i) on or subsequent to the date that is 20 Trading Days prior to the date announced by the Company as the anticipated Fundamental Change Effective Date but (ii) prior to the close of business on the Business Day immediately preceding the related Repurchase Date. The Company shall notify the Holders of an anticipated Fundamental Change Effective Date at least 30 calendar days prior to such Fundamental Change Effective Date.

(c) Notwithstanding any of the provisions of this Section 12.13, in no event shall the Conversion Rate exceed 61.5763 shares per $1,000 principal amount of Securities (subject to adjustment as provided herein).

ARTICLE XIII

SUBORDINATION

Section 13.1. Securities Subordinated to Senior Debt. The Company covenants and agrees, and each Holder of Securities, by such Holder’s acceptance thereof, likewise covenants and agrees, that the Indebtedness represented by the Securities and the payment of the principal of and interest (including Liquidated Damages, if any) on each and all of the Securities is hereby expressly subordinated and junior, to the extent and in the manner set forth and as set forth in this Section 13.1, in right of payment to the prior payment in full of all Senior Debt.

(a) In the event of any distribution of assets of the Company upon any dissolution, winding up, liquidation or reorganization of the Company, whether in bankruptcy, insolvency, reorganization or receivership proceedings or upon an assignment for the benefit of creditors or any other marshalling of the assets and liabilities of the Company or otherwise, the holders of all Senior Debt shall first be entitled to receive payment of the full amount due thereon in respect of all such Senior Debt and all other amounts due or provision shall be made for such amount in cash, or other payments satisfactory to the holders of Senior Debt, before the Holders of any of the Securities are entitled to receive any payment or distribution of any character, whether in cash, securities or other property, on account of the principal of or interest (including Liquidated Damages, if any) on the Indebtedness evidenced by the Securities.

(b) In the event of any acceleration of Maturity of the Securities because of an Event of Default, unless the full amount due in respect of all Senior Debt is paid in cash or other form of payment satisfactory to the holders of Senior Debt, no payment shall be made by the Company with respect to the principal of or interest (including Liquidated

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Damages, if any) on the Securities or to acquire any of the Securities (including any redemption, conversion or cash repurchase pursuant to the exercise of the Repurchase Right), and the Company shall give prompt written notice of such acceleration to such holders of Senior Debt.

(c) In the event of and during the continuance of any default in payment of the principal of or premium, if any, or interest on, rent or other payment obligation in respect of, any Senior Debt, unless all such payments due in respect of such Senior Debt have been paid in full in cash or other payments satisfactory to the holders of Senior Debt, no payment shall be made by the Company with respect to the principal of or interest (including Liquidated Damages, if any) on the Securities or to acquire any of the Securities (including any redemption, conversion or cash repurchase pursuant to the exercise of the Repurchase Right). The Company shall give prompt written notice to the Trustee of any default under any Senior Debt or under any agreement pursuant to which Senior Debt may have been issued.

(d) During the continuance of any event of default with respect to any Designated Senior Debt, as such event of default is defined under any such Designated Senior Debt or in any agreement pursuant to which any Designated Senior Debt has been issued (other than a default in payment of the principal of or premium, if any, or interest on, rent or other payment obligation in respect of any Designated Senior Debt), permitting the holder or holders of such Designated Senior Debt to accelerate the maturity thereof (or in the case of any lease, permitting the landlord either to terminate the lease or to require the Company to make an irrevocable offer to terminate the lease following an event of default thereunder), no payment shall be made by the Company, directly or indirectly, with respect to principal of or interest (including Liquidated Damages, if any) on the Securities for 179 days following notice in writing (a “Payment Blockage Notice”) to the Company, from any holder or holders of such Designated Senior Debt or their representative or representatives or the trustee or trustees under any indenture or under which any instrument evidencing any such Designated Senior Debt may have been issued, that such an event of default has occurred and is continuing, unless such event of default has been cured or waived or such Designated Senior Debt has been paid in full; provided, however, if the maturity of such Designated Senior Debt is accelerated (or in the case of any lease, as a result of such event of default, the landlord under the lease has given the Company notice of its intention to terminate the lease or to require the Company to make an irrevocable offer to terminate the lease), no payment may be made on the Securities until such Designated Senior Debt has been paid in full in cash or other payment satisfactory to the holders of such Designated Senior Debt or such acceleration (or termination, in the case of a lease) has been cured or waived.

For purposes of this Section 13.1(d), such Payment Blockage Notice shall be deemed to include notice of all other events of default under such indenture or instrument which are continuing at the time of the event of default specified in such Payment Blockage Notice. The provisions of this Section 13.1(d) shall apply only to one such Payment Blockage Notice given in any period of 365 days with respect to any issue of Designated Senior Debt, and no such continuing event of default that existed or was continuing on the date of delivery of any Payment Blockage Notice shall be, or shall be made, the basis for a subsequent Payment Blockage Notice.

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(e) In the event that, notwithstanding the foregoing provisions of Sections 13.1(a), 13.1(b), 13.1(c) and 13.1(d), any payment on account of principal or interest (including Liquidated Damages, if any) on the Securities shall be made by or on behalf of the Company and received by the Trustee, by any Holder or by any Paying Agent (or, if the Company is acting as its own Paying Agent, money for any such payment shall be segregated and held in trust):

(i) after the occurrence of an event specified in Section 13.1(a) or 13.1(b), then, unless all Senior Debt is paid in full in cash, or provision shall be made therefor,

(ii) after the happening of an event of default of the type specified in Section 13.1(c) above, then, unless the amount of such Senior Debt then due shall have been paid in full, or provision made therefor or such event of default shall have been cured or waived, or

(iii) after the happening of an event of default of the type specified in Section 13.1(d) above and delivery of a Payment Blockage Notice, then, unless such event of default shall have been cured or waived or the 179-day period specified in Section 13.1(d) shall have expired,

such payment (subject, in each case, to the provisions of Section 13.7 hereof) shall be held in trust for the benefit of, and shall be immediately paid over to, the holders of Designated Senior Debt (unless an event described in Section 13.1(a), (b) or (c) has occurred, in which case the payment shall be held in trust for the benefit of, and shall be immediately paid over to all holders of Senior Debt) or their representative or representatives or the trustee or trustees under any indenture under which any instruments evidencing any of the Designated Senior Debt or Senior Debt, as the case may be, may have been issued, as their interests may appear.

Section 13.2. Subrogation. Subject to the payment in full of all Senior Debt to which the Indebtedness evidenced by the Securities is in the circumstances subordinated as provided in Section 13.1 hereof, the Holders of the Securities shall be subrogated to the rights of the holders of such Senior Debt to receive payments or distributions of cash, property or securities of the Company applicable to such Senior Debt until all amounts owing on the Securities shall be paid in full, and, as between the Company, its creditors other than holders of such Senior Debt, and the Holders of the Securities, no such payment or distribution made to the holders of Senior Debt by virtue of this Article which otherwise would have been made to the holders of the Securities shall be deemed to be a payment by the Company on account of such Senior Debt, provided that the provisions of this Article are and are intended solely for the purpose of defining the relative rights of the Holders of the Securities, on the one hand, and the holders of Senior Debt, on the other hand.

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Section 13.3. Obligation of the Company is Absolute and Unconditional. Nothing contained in this Article or elsewhere in this Indenture or in the Securities is intended to or shall impair, as between the Company, its creditors other than the holders of Senior Debt, and the Holders of the Securities, the obligation of the Company, which is absolute and unconditional, to pay to the Holders of the Securities the principal of and interest (including Liquidated Damages, if any) on the Securities as and when the same shall become due and payable in accordance with their terms, or is intended to or shall affect the relative rights of the Holders of the Securities and creditors of the Company other than the holders of Senior Debt, nor shall anything contained herein or therein prevent the Trustee or the Holder of any Security from exercising all remedies otherwise permitted by applicable law upon default under this Indenture, subject to the rights, if any, under this Article of the holders of Senior Debt in respect of cash, property or securities of the Company received upon the exercise of any such remedy.

Section 13.4. Maturity of or Default on Senior Debt. Upon the maturity of any Senior Debt by lapse of time, acceleration or otherwise, all principal of or premium, if any, or interest on, rent or other payment obligations in respect of all such matured Senior Debt shall first be paid in full, or such payment shall have been duly provided for, before any payment on account of principal or interest (including Liquidated Damages, if any) is made upon the Securities.

Section 13.5. Payments on Securities Permitted. Except as expressly provided in this Article, nothing contained in this Article shall affect the obligation of the Company to make, or prevent the Company from making, payments of the principal of or interest (including Liquidated Damages, if any) on the Securities in accordance with the provisions hereof and thereof, or shall prevent the Trustee or any Paying Agent from applying any moneys deposited with it hereunder to the payment of the principal of or interest (including Liquidated Damages, if any) on the Securities.

Section 13.6. Effectuation of Subordination by Trustee. Each Holder of Securities, by such Holder’s acceptance thereof, authorizes and directs the Trustee on such Holder’s behalf to take such action as may be necessary or appropriate to effectuate the subordination provided in this Article and appoints the Trustee such Holder’s attorney-in-fact for any and all such purposes.

Upon any payment or distribution of assets of the Company referred to in this Article, the Trustee and the Holders of the Securities shall be entitled to rely upon any order or decree made by any court of competent jurisdiction in which any such dissolution, winding up, liquidation or reorganization proceeding affecting the affairs of the Company is pending or upon a certificate of the trustee in bankruptcy, receiver, assignee for the benefit of creditors, liquidating trustee or agent or other Person making any payment or distribution, delivered to the Trustee or to the Holders of the Securities, for the purpose of ascertaining the Persons entitled to participate in such payment or distribution, and as to other facts pertinent to the right of such Persons under this Article, and if such evidence is not furnished, the Trustee may defer any payment to such Persons pending judicial determination as to the right of such Persons to receive such payment.

Section 13.7. Knowledge of Trustee. Notwithstanding the provision of this Article or any other provisions of this Indenture, the Trustee shall not be charged with knowledge of the existence of any Senior Debt, of any default in payment of principal of, premium, if any, or

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interest on, rent or other payment obligation in respect of any Senior Debt, or of any facts which would prohibit the making of any payment of moneys to or by the Trustee, or the taking of any other action by the Trustee, unless a Responsible Officer of the Trustee having responsibility for the administration of the trust established by this Indenture shall have received written notice thereof from the Company, any Holder of Securities, any Paying or Conversion Agent of the Company or the holder or representative of any class of Senior Debt, and, prior to the receipt of any such written notice, the Trustee shall be entitled in all respects to assume that no such default or facts exist; provided, however, that unless on the third Business Day prior to the date upon which by the terms hereof any such moneys may become payable for any purpose the Trustee shall have received the notice provided for in this Section 13.7, then, anything herein contained to the contrary notwithstanding, the Trustee shall have full power and authority to receive such moneys and apply the same to the purpose for which they were received, and shall not be affected by any notice to the contrary which may be received by it on or after such date.

Section 13.8. Trustee’s Relation to Senior Debt. The Trustee shall be entitled to all the rights set forth in this Article with respect to any Senior Debt at the time held by it, to the same extent as any other holder of Senior Debt and nothing in this Indenture shall deprive the Trustee of any of its rights as such holder.

Nothing contained in this Article shall apply to claims of or payments to the Trustee under or pursuant to Section 5.8 hereof.

With respect to the holders of Senior Debt, the Trustee undertakes to perform or to observe only such of its covenants and obligations as are specifically set forth in this Article, and no implied covenants or obligations with respect to the holders of Senior Debt shall be read into this Indenture against the Trustee. The Trustee shall not be deemed to owe any fiduciary duty to the holders of Senior Debt and the Trustee shall not be liable to any holder of Senior Debt if it shall pay over or deliver to Holders, the Company or any other Person moneys or assets to which any holder of Senior Debt shall be entitled by virtue of this Article or otherwise.

Section 13.9. Rights of Holders of Senior Debt Not Impaired. No right of any present or future holder of any Senior Debt to enforce the subordination herein shall at any time or in any way be prejudiced or impaired by any act or failure to act on the part of the Company or by any noncompliance by the Company with the terms, provisions and covenants of this Indenture, regardless of any knowledge thereof any such holder may have or be otherwise charged with.

Section 13.10. Modification of Terms of Senior Debt. Any renewal or extension of the time of payment of any Senior Debt or the exercise by the holders of Senior Debt of any of their rights under any instrument creating or evidencing Senior Debt, including without limitation the waiver of default thereunder, may be made or done all without notice to or assent from the Holders of the Securities or the Trustee.

No compromise, alteration, amendment, modification, extension, renewal or other change of, or waiver, consent or other action in respect of, any liability or obligation under or in respect of, or of any of the terms, covenants or conditions of any indenture or other instrument under which any Senior Debt is outstanding or of such Senior Debt, whether or not such release is in accordance with the provisions or any applicable document, shall in any way alter or affect any of the provisions of this Article or of the Securities relating to the subordination thereof.

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Section 13.11. Certain Conversions Not Deemed Payment. For the purposes of this Article XIII only:

(a) the issuance and delivery of junior securities upon conversion of Securities in accordance with Article XII hereof shall not be deemed to constitute a payment or distribution on account of the principal of or interest (including Liquidated Damages, if any) on Securities or on account of the purchase or other acquisition of Securities, and

(b) the payment, issuance or delivery of cash (except in satisfaction of fractional shares pursuant to Section 12.3 hereof), property or securities (other than junior securities) upon conversion of a Security shall be deemed to constitute payment on account of the principal of or interest (including Liquidated Damages, if any) on such Security.

For the purposes of this Section 13.11, the term “junior securities” means:

(a) shares of any common stock of the Company or

(b) other securities of the Company that are subordinated in right of payment to all Senior Debt that may be outstanding at the time of issuance or delivery of such securities to substantially the same extent as, or to a greater extent that, the Securities are so subordinated as provided in this Article.

Nothing contained in this Article XIII or elsewhere in this Indenture or in the Securities is intended to or shall impair, as among the Company, its creditors (other than holders of Senior Debt) and the Holders of Securities, the right, which is absolute and unconditional, of the Holder of any Security to convert such Security in accordance with Article XII hereof.

ARTICLE XIV

OTHER PROVISIONS OF GENERAL APPLICATION

Section 14.1. Trust Indenture Act Controls. This Indenture is subject to the provisions of the TIA which are required to be part of this Indenture, and shall, to the extent applicable, be governed by such provisions.

Section 14.2. Notices. Any notice or communication to the Company or the Trustee is duly given if in writing and delivered in person or mailed by first-class mail to the address set forth below:

(a) if to the Company:

  Nektar Therapeutics

  150 Industrial Road

  San Carlos, California 94070

  Attention: Nevan Elam, Esq.

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  with a copy to:

  Cooley Godward LLP

  Five Palo Alto Square

  3000 El Camino Real

  Palo Alto, California 94304-1130

  Attention: John Geschke, Esq.

(b) if to the Trustee:

  J.P. Morgan Trust Company, National Association

  600 Travis Street

  Suite 1150

  Houston, Texas 77002

  Attention: Corporate Trust Services

The Company or the Trustee by notice to the other may designate additional or different addresses for subsequent notices or communications.

Any notice or communication to a Holder shall be mailed by first-class mail to his address shown on the Register kept by the Registrar. Failure to mail a notice or communication to a Holder or any defect in such notice or communication shall not affect its sufficiency with respect to other Holders.

If a notice or communication is mailed or sent in the manner provided above within the time prescribed, it is duly given as of the date it is mailed, whether or not the addressee receives it, except that notice to the Trustee shall only be effective upon receipt thereof by the Trustee.

If the Company mails a notice or communication to Holders, it shall mail a copy to the Trustee at the same time.

Section 14.3. Communication by Holders with Other Holders. Holders may communicate pursuant to Section 312(b) of the TIA with other Holders with respect to their rights under the Securities or this Indenture. The Company, the Trustee, the Registrar and anyone else shall have the protection of Section 312(c) of the TIA.

Section 14.4. Acts of Holders of Securities. (a) Any request, demand, authorization, direction, notice, consent, waiver or other action provided by this Indenture to be given or taken by Holders of Securities may be embodied in and evidenced by:

(i) one or more instruments of substantially similar tenor signed by such Holders in person or by agent or proxy duly appointed in writing;

(ii) the record of Holders of Securities voting in favor thereof, either in person or by proxies duly appointed in writing, at any meeting of Holders of Securities duly called and held in accordance with the provisions of Article VIII; or

(iii) a combination of such instruments and any such record.

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Except as herein otherwise expressly provided, such action shall become effective when such instrument or instruments or record or both are delivered to the Trustee and, where it is hereby expressly required, to the Company. Such instrument or instruments and record (and the action embodied therein and evidenced thereby) are herein sometimes referred to as the “Act” of the Holders of Securities signing such instrument or instruments and so voting at such meeting. Proof of execution of any such instrument or of a writing appointing any such agent or proxy, or of the holding by any Person of a Security, shall be sufficient for any purpose of this Indenture and (subject to Section 5.1 hereof) conclusive in favor of the Trustee and the Company if made in the manner provided in this Section. The record of any meeting of Holders of Securities shall be proved in the manner provided in Section 8.6 hereof.

(b) The fact and date of the execution by any Person of any such instrument or writing may be provided in any manner which the Trustee reasonably deems sufficient.

(c) The principal amount and serial numbers of Securities held by any Person, and the date of such Person holding the same, shall be proved by the Register.

(d) Any request, demand, authorization, direction, notice, consent, election, waiver or other Act of the Holders of any Security shall bind every future Holder of the same Security and the Holder of every Security issued upon the registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered to be done by the Trustee or the Company in reliance thereon, whether or not notation of such action is made upon such Security.

Section 14.5. Certificate and Opinion as to Conditions Precedent. In any case where several matters are required to be certified by, or covered by an opinion of, any specified Person, it is not necessary that all such matters be certified by, or covered by the opinion of, only one such Person, or that they be so certified or covered by only one document, but one such Person may certify or give an opinion with respect to some matters and one or more other such Persons as to other matters, and any such Person may certify or give an opinion as to such matters in one or several documents.

Any certificate or opinion of an officer of the Company may be based, insofar as it relates to legal matters, upon an Opinion of Counsel, unless such officer knows, or in the exercise of reasonable care should know, that the Opinion of Counsel with respect to the matters upon which such certificate or opinion is based is erroneous. Any such Opinion of Counsel may be based, insofar as it relates to factual matters, upon a certificate or representations by, an officer or officers of the Company stating that the information with respect to such factual matters is in the possession of the Company, unless such counsel knows, or in the exercise of reasonable care should know, that the certificate or representations with respect to such matters are erroneous.

Where any Person is required to make, give or execute two or more applications, requests, consents, certificates, statements, opinions or other instruments under this Indenture, they may, but need not, be consolidated and form one instrument.

Upon any application or request by the Company to the Trustee to take any action under any provision of this Indenture, the Company shall furnish to the Trustee an Officers’ Certificate

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stating that all conditions precedent, if any, provided for in this Indenture relating to the proposed action have been complied with and an Opinion of Counsel stating that in the opinion of such Counsel all such conditions precedent, if any, have been complied with, except that in the case of any such application or request as to which the furnishing of such documents is specifically required by any provision of this Indenture relating to such particular application or request, no additional certificate or opinion need be furnished.

Section 14.6. Statements Required in Certificate or Opinion. Each certificate or opinion with respect to compliance with a condition or covenant provided for in this Indenture shall include:

(a) a statement that each individual signing such certificate or opinion on behalf of the Company has read such covenant or condition and the definitions herein relating thereto;

(b) a brief statement as to the nature and scope of the examination or investigation upon which the statements or opinions contained in such certificate or opinion are based;

(c) a statement that, in the opinion of each such individual, he has made such examination or investigation as is necessary to enable him to express an informed opinion as to whether or not such covenant or condition has been complied with; and

(d) a statement as to whether, in the opinion of each such individual, such condition or covenant has been complied with.

Section 14.7. Effect of Headings and Table of Contents. The Article and Section headings herein and the Table of Contents are for convenience only and shall not affect the construction hereof.

Section 14.8. Successors and Assigns. All covenants and agreements in this Indenture by the Company shall bind its successors and assigns, whether so expressed or not.

Section 14.9. Separability Clause. In case any provision in this Indenture or the Securities shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

Section 14.10. Benefits of Indenture. Nothing contained in this Indenture or in the Securities, express or implied, shall give to any Person, other than the parties hereto and their successors hereunder, the holders of Senior Debt and the Holders of Securities, any benefit or legal or equitable right, remedy or claim under this Indenture.

Section 14.11. Governing Law. THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

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Section 14.12. Counterparts. This instrument may be executed in any number of counterparts, each of which when so executed shall be deemed to be an original but all such counterparts shall together constitute but one and the same instrument.

Section 14.13. Legal Holidays. In any case where any Interest Payment Date, Redemption Date or Stated Maturity of any Security or the last day on which a Holder of a Security has a right to convert such Security shall not be a Business Day at any Place of Payment or Place of Conversion, then (notwithstanding any other provision of this Indenture or of the Securities) payment of interest (including Liquidated Damages, if any) or principal, or conversion of the Securities, need not be made at such Place of Payment or Place of Conversion on such day, but may be made on the next succeeding Business Day at such Place of Payment or Place of Conversion with the same force and effect as if made on the Interest Payment Date or Redemption Date or at the Stated Maturity or on such last day for conversion, provided, that in the case that payment is made on such succeeding Business Day, no interest shall accrue on the amount so payable for the period from and after such Interest Payment Date, Redemption Date or Stated Maturity, as the case may be.

Section 14.14. Recourse Against Others. No recourse for the payment of the principal of or interest (including Liquidated Damages, if any) on any Security, or for any claim based thereon or otherwise in respect thereof, shall be had against any incorporator, shareholder, officer or director, as such, past, present or future, of the Company or of any successor corporation, whether by virtue of any constitution, statute or rule of law or by the enforcement of any assessment or penalty or otherwise, all such liability being, by the acceptance thereof and as part of the consideration for the issue thereof, expressly waived and released.

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IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly executed all as of the day and year first above written.

NEKTAR THERAPEUTICS
By:	/s/ Ajit Gill
Name:	Ajit Gill
Title:	Chief Executive Officer
J.P. MORGAN TRUST COMPANY, NATIONAL ASSOCIATION
By:	/s/ Mary Jane Henson
Name:	Mary Jane Henson
Title:	Vice President

80

EXHIBIT A

FORM OF SECURITY

[FACE OF SECURITY]

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (“DTC”) TO NEKTAR THERAPEUTICS (OR ITS SUCCESSOR) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, CONVERSION OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.¹

THE SECURITY EVIDENCED BY THIS CERTIFICATE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED OR SOLD EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE. BY ACQUISITION HEREOF, THE HOLDER (1) REPRESENTS THAT IT IS A “QUALIFIED INSTITUTIONAL BUYER” AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT; (2) AGREES THAT IT WILL NOT WITHIN TWO YEARS AFTER THE ORIGINAL ISSUANCE OF THIS SECURITY RESELL OR OTHERWISE TRANSFER THE SECURITY EVIDENCED HEREBY OR THE COMMON STOCK ISSUABLE UPON CONVERSION OF SUCH SECURITY EXCEPT (A) TO NEKTAR THERAPEUTICS (THE “COMPANY”) OR ANY SUBSIDIARY THEREOF, (B) TO A QUALIFIED INSTITUTIONAL BUYER IN COMPLIANCE WITH RULE 144A UNDER THE SECURITIES ACT, (C) PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE), (D) PURSUANT TO ANY OTHER AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT OR (E) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER; AND (3) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THE SECURITY EVIDENCED HEREBY IS TRANSFERRED (OTHER THAN A TRANSFER PURSUANT TO CLAUSE 2(E) ABOVE) A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. IN CONNECTION WITH ANY TRANSFER OF THE SECURITY EVIDENCED HEREBY WITHIN TWO YEARS AFTER THE ORIGINAL ISSUANCE OF SUCH SECURITY (OTHER THAN A TRANSFER PURSUANT TO CLAUSE (2)(E) ABOVE), THE HOLDER MUST CHECK THE APPROPRIATE BOX SET FORTH ON THE REVERSE HEREOF RELATING TO THE MANNER OF SUCH TRANSFER AND SUBMIT THIS CERTIFICATE TO THE TRUSTEE (OR ANY SUCCESSOR TRUSTEE, AS APPLICABLE). IF THE PROPOSED TRANSFER IS

¹ This legend should be included on if the Security is issued in global form

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PURSUANT TO CLAUSE (2)(C) OR (2)(D) ABOVE, THE HOLDER MUST, PRIOR TO SUCH TRANSFER, FURNISH TO THE TRUSTEE (OR ANY SUCCESSOR TRUSTEE, AS APPLICABLE), SUCH CERTIFICATIONS, LEGAL OPINIONS OR OTHER INFORMATION AS THE COMPANY MAY REASONABLY REQUIRE TO CONFIRM THAT SUCH TRANSFER IS BEING MADE PURSUANT TO AN EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT. THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF THE SECURITY EVIDENCED HEREBY PURSUANT TO CLAUSE (2)(E) ABOVE OR THE EXPIRATION OF TWO YEARS FROM THE ORIGINAL ISSUANCE OF THE SECURITY EVIDENCED HEREBY.

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NEKTAR THERAPEUTICS

3.25% Convertible Subordinated Note due 2012

CUSIP NO. 640268 AG 3

No. 1 $315,000,000

NEKTAR THERAPEUTICS, a Delaware corporation (the “Company,” which term includes any successor corporation under the Indenture hereinafter referred to), for value received, hereby promises to pay to                                     , or its registered assigns, the principal sum of Three Hundred Fifteen Million U.S. Dollars ($315,000,000) on September 28, 2012.

Interest Payment Dates: March 28 and September 28, commencing March 28, 2006

Regular Record Dates: March 13 and September 13

Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

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IN WITNESS WHEREOF, the Company has caused this Security to be duly executed manually or by facsimile by its duly authorized officers.

Dated: September 28, 2005

NEKTAR THERAPEUTICS

By:

Name:

Title:

Trustee’s Certificate of Authentication

This is one of the Securities described in the

within-named Indenture.

J.P. MORGAN TRUST COMPANY,

NATIONAL ASSOCIATION, as Trustee

By:
	Authorized Signatory
Dated:	September 28, 2005

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[REVERSE OF SECURITY]

NEKTAR THERAPEUTICS

3.25% Convertible Subordinated Note due 2012

Capitalized terms used herein but not defined shall have the meanings assigned to them in the Indenture referred to below unless otherwise indicated.

1. Principal and Interest.

Nektar Therapeutics, a Delaware corporation (the “Company”) promises to pay interest on the principal amount of this Security at the rate of 3.25 percent per annum from the date of issuance until repayment at Maturity, redemption or repurchase. The Company will pay interest on this Security semiannually in arrears on March 28 and September 28 of each year (each an “Interest Payment Date”), commencing March 28, 2006, to Holders of record as of the applicable Regular Record Date.

Interest on the Securities shall be computed on the basis of a 360-day year of twelve 30-day months.

To the maximum extent permitted by applicable law, in the event that any amounts owing in respect of the principal of or interest on the Securities is not paid in full on the due date therefor, interest shall accrue on such unpaid amounts at the rate of 3.25% per annum until such amounts are paid in full.

In accordance with the terms of the Registration Rights Agreement, dated September 28, 2005, among the Company and Merrill Lynch, Pierce, Fenner & Smith Incorporated, Lehman Brothers Inc., Goldman Sachs & Co., Deutsche Bank Securities Inc., W.R. Hambrecht + Co, LLC, Leerink Swann & Company, SG Cowen & Co., LLC and SunTrust Capital Markets, Inc. (the “Registration Rights Agreement”), during the first 90 days following a Registration Default (as defined in the Registration Rights Agreement), the interest rate borne by the Securities shall, subject to the Company’s right to suspend the effectiveness of the Shelf Registration Statement as set forth in the Registration Rights Agreement, be increased by 0.25% on:

(a) December 27, 2005, if the shelf registration statement (the “Shelf Registration Statement”) is not filed prior to or on December 27, 2005;

(b) April 26, 2006, if the Shelf Registration Statement is not declared effective by the Securities and Exchange Commission prior to or on April 26, 2006;

(c) the day after the fifth Business Day after the Shelf Registration Statement, previously declared effective, ceases to be effective or fails to be usable, if a post-effective amendment (or report filed pursuant to the Exchange Act) that cures the Shelf Registration Statement is not filed with the Securities and Exchange Commission during such five Business Day period; or

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(d) the day following the 45th, 60th or 90th day, as the case may be, of any period that the prospectus contained in the Shelf Registration Statement has been suspended, if such suspension has not been terminated.

From and after the 91st day following such Registration Default, the interest rate borne by the Securities shall be increased by 0.50%. In no event shall the interest rate borne by the Securities be increased by more than 0.50%.

Any amount of additional interest will be payable in cash semiannually, in arrears, on each Interest Payment Date and will cease to accrue on the date the Registration Default is cured. The Holder of this Security is entitled to the benefits of the Registration Rights Agreement.

2. Method of Payment.

Interest on any Security which is payable, and is punctually paid or duly provided for, on any Interest Payment Date shall be paid to the Person in whose name that Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest.

Principal of, and interest on, Global Securities will be payable to the Depositary in immediately available funds.

Principal on Physical Securities will be payable at the office or agency of the Company maintained for such purpose, initially the Corporate Trust Office of the Trustee. Interest on Physical Securities will be payable by (i) check mailed to the address of the Person entitled thereto as such address shall appear in the Register, or (ii) upon application to the Registrar not later than the relevant Record Date by a Holder of an aggregate principal amount in excess of $5,000,000, wire transfer in immediately available funds.

3. Paying Agent and Registrar.

Initially, J.P. Morgan Trust Company, National Association, the Trustee under the Indenture, will act as Paying Agent and Registrar. The Company may change the Paying Agent or Registrar without notice to any Holder.

4. Indenture.

The Company issued this Security under an Indenture, dated as of September 28, 2005 (the “Indenture”), between the Company and J.P. Morgan Trust Company, National Association, as trustee (the “Trustee”). The terms of the Security include those stated in the Indenture and those made part of the Indenture by reference to the Trust Indenture Act of 1939, as amended (“TIA”). This Security is subject to all such terms, and Holders are referred to the Indenture and the TIA for a statement of all such terms. To the extent permitted by applicable law, in the event of any inconsistency between the terms of this Security and the terms of the Indenture, the terms of the Indenture shall control.

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5. Redemption.

The Securities may not be redeemed prior to September 28, 2008. On and after September 28, 2008, the Securities may be redeemed at the election of the Company, as a whole or from time to time in part, at a Redemption Price, payable in cash, equal to $1,000 per $1,000 principal amount of the Securities to be redeemed, plus any interest accrued but not paid prior to, but excluding the date of redemption (the “Redemption Date”) if the Closing Price of the Common Stock has exceeded 150% of the Conversion Price (as may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30 Trading Day period ending on the Trading Day prior to the date of mailing of the notice of redemption. Any such redemption shall be upon not less than 30 nor more than 60 days’ notice.

On and after the Redemption Date, interest shall cease to accrue on Securities or portions of Securities called for redemption, unless the Company shall default in the payment of the Redemption Price and accrued and unpaid interest.

6. Repurchase Right Upon a Fundamental Change.

If a Fundamental Change occurs, a Holder of Securities, at the Holder’s option, shall have the right, in accordance with the provisions of the Indenture, to require the Company to repurchase the Securities (or any portion of the principal amount hereof that is at least $1,000 or an integral multiple thereof, provided that the portion of the principal amount of this Security to be Outstanding after such repurchase is at least equal to $1,000) for cash at the Repurchase Price plus any interest accrued and unpaid to the Repurchase Date.

A Company Notice will be given by the Company to the Holders as provided in the Indenture. To exercise a repurchase right, a Holder must deliver to the Trustee a written Fundamental Change Repurchase Notice as provided in the Indenture. The Holder shall have the right to withdraw any Fundamental Change Repurchase Notice (in whole or in any portion of the principal amount thereof that is $1,000 or an integral multiple of $1,000) at any time prior to the close of business on the Business Day next preceding the Repurchase Date by delivering a written notice of withdrawal to the Trustee in accordance with the terms of the Indenture.

7. Conversion Rights.

Subject to and upon compliance with the provisions of the Indenture, the Holder of Securities is entitled, at such Holder’s option, at any time before the Stated Maturity of the principal of the Securities, to convert the Holder’s Securities (or any portion of the principal amount hereof which is $1,000 or an integral multiple thereof) at the principal amount thereof or of such portion, into duly authorized, fully paid and nonassessable shares of Common Stock of the Company at the Conversion Rate in effect at the time of conversion.

In the case of a Security (or a portion thereof) called for redemption, such conversion right in respect of the Security (or such portion thereof) so called, shall expire at the close of business on the Business Day next preceding the Redemption Date, unless the Company defaults in making the payment due upon redemption. Securities as to which a Fundamental Change Repurchase Notice has been given may be converted pursuant to Article XII of the Indenture only to the extent that the Fundamental Change Repurchase Notice has been withdrawn in accordance with the terms of the Indenture.

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The Conversion Rate shall be initially equal to 46.4727 shares of Common Stock per $1,000 principal amount of the Securities. The Conversion Rate shall be adjusted under certain circumstances as provided in the Indenture. Holders who convert Securities in connection with a Fundamental Change shall be entitled to a Make-Whole Payment, if any, consisting of an increase in the Conversion Rate in the manner and to the extent set forth in Section 12.13 of the Indenture.

To exercise the conversion right, the Holder must complete the conversion notice on the reverse hereof, deliver such completed conversion notice and such Security to be converted to the office of the Conversion Agent, furnish appropriate endorsement and transfer documents and otherwise comply with the applicable requirements of Article XII of the Indenture. Any Security surrendered for conversion during the period from the close of business on any Regular Record Date to the opening of business on the next succeeding Interest Payment Date (other than any Security whose Maturity is prior to such Interest Payment Date) shall also be accompanied by payment in New York Clearing House funds or other funds acceptable to the Company of an amount equal to the interest payable on such Interest Payment Date on the principal amount of the Securities being surrendered for conversion; provided, however, that no such payment need be made (a) if a Repurchase Date following a Fundamental Change occurs on a date that is after a Regular Record Date and on or prior to the next Interest Payment Date, (b) only to the extent of overdue interest, if any overdue interest exists at the time of conversion with respect to such Security, (c) if a Redemption Date for the Securities occurs on a date that is after a Regular Record Date and on or prior to the next Interest Payment Date, or (d) the Securities are surrendered for conversion on or after September 13, 2012.

No fractional shares of Common Stock will be issued upon conversion of any Securities. Instead of any fractional share of Common Stock which would otherwise be issued upon conversion of such Securities, the Company shall pay a cash adjustment as provided in the Indenture.

8. Subordination.

The Indebtedness evidenced by this Security is, to the extent and in the manner provided in the Indenture, subordinated and subject in right of payment to the prior payment in full of all amounts then due on all Senior Debt of the Company, and this Security is issued subject to such provisions of the Indenture with respect thereto. Each Holder of this Security, by accepting the same, (a) agrees to and shall be bound by such provisions, (b) authorizes and directs the Trustee on such Holder’s behalf to take such action as may be necessary or appropriate to effectuate the subordination so provided and (c) appoints the Trustee such Holder’s attorney-in-fact for any and all such purposes.

9. Denominations; Transfer; Exchange.

The Securities are issuable in registered form, without coupons, in denominations of $1,000 and integral multiples of $1,000 in excess thereof. A Holder may register the transfer or

A-8

exchange of Securities in accordance with the Indenture. The Registrar may require a Holder, among other things, to furnish appropriate endorsements and transfer documents and the Company may require a Holder to pay any taxes and fees required by law or permitted by the Indenture.

In the event of a redemption in part, the Company will not be required (a) to register the transfer of, or exchange, Securities for a period of 15 days immediately preceding the date notice is given identifying the serial numbers of the Securities called for such redemption, or (b) to register the transfer of, or exchange, any such Securities, or portion thereof, called for redemption.

In the event of redemption, conversion or repurchase of the Securities in part only, a new Security or Securities for the unredeemed, unconverted or unrepurchased portion thereof will be issued in the name of the Holder hereof.

10. Persons Deemed Owners.

The registered Holder of this Security shall be treated as its owner for all purposes.

11. Unclaimed Money.

The Trustee and the Paying Agent shall pay to the Company any money held by them for the payment of principal or interest that remains unclaimed for two years after the date upon which such payment shall have become due. After payment to the Company, Holders entitled to the money must look to the Company for payment as general creditors unless an applicable abandoned property law designates another Person, and all liability of the Trustee and such Paying Agent with respect to such money shall cease.

12. Discharge Prior to Redemption or Maturity.

Subject to certain conditions contained in the Indenture, the Company may discharge its obligations under the Securities and the Indenture if (1) (a) all of the Outstanding Securities shall become due and payable at their scheduled Maturity within one year or (b) all of the Outstanding Securities have been called for redemption, and (2) the Company shall have deposited with the Trustee money and/or U.S. Government Obligations sufficient to pay the principal of, and interest on, all of the Outstanding Securities on the date of Maturity or redemption, as the case may be.

13. Amendment; Supplement; Waiver.

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Securities under the Indenture at any time by the Company and the Trustee with the consent of the Holders of a majority in aggregate principal amount of the Outstanding Securities (or such lesser amount as shall have acted at a meeting pursuant to the provisions of the Indenture). The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Securities at the time Outstanding, on behalf of the Holders of all the Securities, to waive compliance by the Company with certain provisions of the

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Indenture and certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security or such other Security.

No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of and interest (including Liquidated Damages, if any) on this Security at the times, places and rate, and in the coin or currency, herein prescribed or to convert this Security (or pay cash in lieu of conversion) as provided in the Indenture.

14. Defaults and Remedies.

The Indenture provides that an Event of Default with respect to the Securities occurs when any of the following occurs:

(a) the Company defaults in the payment of the principal on any of the Securities when it becomes due and payable at Maturity, upon redemption or exercise of a Repurchase Right or otherwise, whether or not such payment is prohibited by the subordination provisions of Article XIII of the Indenture;

(b) the Company defaults in the payment of interest on any of the Securities (including Liquidated Damages, if any) when it becomes due and payable and such default continues for a period of 30 days, whether or not such payment is prohibited by the subordination provisions of Article XIII of the Indenture;

(c) the Company fails to deliver shares of Common Stock, together with cash instead of fractional shares, when such shares of Common Stock and cash instead of fractional shares are required to be delivered following conversion of a Security in accordance with the provisions of Article XII of the Indenture, and such failure continues for 10 days;

(d) the Company fails to perform or observe any other term, covenant or agreement contained in the Securities or the Indenture and such default continues for a period of 60 days after written notice of such failure is given as specified in the Indenture;

(e) (i) the Company fails to make any payment by the end of the applicable grace period, if any, after the maturity of any Indebtedness for borrowed money in an amount in excess of $25,000,000 (provided that such failure shall not constitute an Event of Default if (1) the Company determines, in good faith, that a lessor under a lease described in clause (3)(b) of the definition of Indebtedness set forth in the Indenture breached a covenant under the lease and the Company has given notice of the breach to the lessor and the Trustee and (2) as a result of the breach, the Company withholds payment under the lease (a “Default Exception”)), or (ii) there is an acceleration of any Indebtedness for borrowed money in an amount in excess of $25,000,000 because of a default with respect to such Indebtedness (other than a Default Exception) without such

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Indebtedness having been discharged or such acceleration having been cured, waived, rescinded or annulled, in the case of either clause (i) or (ii) above, for a period of 30 days after written notice is given to the Company as specified in the Indenture;

(f) the failure to provide the Company Notice in accordance with the terms of Section 11.3(a) of the Indenture; or

(g) there are certain events of bankruptcy, insolvency or reorganization of the Company.

If an Event of Default shall occur and be continuing, the principal of all the Securities may be declared due and payable in the manner and with the effect provided in the Indenture.

15. Authentication.

This Security shall not be valid until the Trustee (or authenticating agent) executes the certificate of authentication on the other side of this Security.

16. Abbreviations.

Customary abbreviations may be used in the name of a Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the entireties), JT TEN (= joint tenants with right of survivorship and not as tenants in common), CUST (= Custodian) and U/G/M/A (= Uniform Gifts to Minors Act).

17. Additional Rights of Holders of Transfer Restricted Securities.

In addition to the rights provided to Holders under the Indenture, Holders of Transfer Restricted Securities shall have all the rights set forth in the Registration Rights Agreement.

18. CUSIP Numbers.

Pursuant to a recommendation promulgated by the Committee on Uniform Security Identification Procedures, the Company has caused CUSIP numbers to be printed on this Security and the Trustee may use CUSIP numbers in notices of redemption as a convenience to Holders. No representation is made as to the accuracy of such numbers either as printed on this Security or as contained in any notice of redemption and reliance may be placed only on the other identification numbers placed thereon.

19. Governing Law.

The Indenture and this Security shall be governed by, and construed in accordance with, the law of the State of New York.

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20. Successor Corporation.

In the event a successor corporation assumes all the obligations of the Company under this Security, pursuant to the terms hereof and of the Indenture, the Company will be released from all such obligations.

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ASSIGNMENT FORM

To assign this Security, fill in the form below and have your signature guaranteed: (I) or (we) assign and transfer this Security to:

(Insert assignee’s soc. sec. or tax I.D. no.)

(Print or type assignee’s name, address and zip code)

and irrevocably appoint                                                                                                                                                                            

to transfer this Security on the books of the Company. The agent may substitute another to act for him.

Dated:	Your Name:
		(Print your name exactly as it appears on the face of this Security)

Your Signature:
	(Sign exactly as your name appears on the face of this Security)

Signature Guarantee^*:

^* Participant in a recognized Signature Guarantee Medallion Program (or other signature guarantor acceptable to the Trustee).

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In connection with any transfer of this Security occurring prior to the date which is the earlier of the end of the period referred to in Rule 144(k) under the Securities Act, the undersigned confirms that:

[Check One]

¨ (a) this Security is being transferred in compliance with the exemption from registration under the Securities Act of 1933, as amended, provided by Rule 144A thereunder.

or

¨ (b) this Security is being transferred other than in accordance with (a) above and documents are being furnished which comply with the conditions of transfer set forth in this Security and the Indenture.

or

¨ (c) this Security is being transferred pursuant to a registration statement which has been declared effective under the Securities Act of 1933, as amended, and which continues to be effective at the time of transfer.

If none of the foregoing boxes is checked, the Trustee or other Registrar shall not be obligated to register this Security in the name of any Person other than the Holder hereof unless the conditions to any such transfer of registration set forth herein and in Sections 2.7, 2.8 and 2.9 of the Indenture shall have been satisfied.

Dated:
	NOTICE: The signature to this assignment must correspond with the name as written upon the face of the within-mentioned instrument in every particular, without alteration or any change whatsoever.
	Signature Guarantee:
	Signature must be guaranteed by a participant in a recognized signature guaranty medallion program or other signature guarantor acceptable to the Trustee.

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TO BE COMPLETED BY PURCHASER IF (a) ABOVE IS CHECKED.

The undersigned represents and warrants that it is purchasing this Security for its own account or an account with respect to which it exercises sole investment discretion, in each case for investment and not with a view to distribution, and that it and any such account is a “Qualified Institutional Buyer” within the meaning of Rule 144A under the Securities Act of 1933 and is aware that the sale to it is being made in reliance on Rule 144A and acknowledges that it has received such information regarding the Company as the undersigned has requested pursuant to Rule 144A or has determined not to request such information and that it is aware that the transferor is relying upon the undersigned’s foregoing representations in order to claim the exemption from registration provided by Rule 144A.

Dated:                             

NOTICE: To be executed by an executive officer

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CONVERSION NOTICE

TO:	NEKTAR THERAPEUTICS
	150 Industrial Road
	San Carlos, California 94070

The undersigned registered owner of this Security hereby irrevocably exercises the option to convert this Security, or the portion hereof (which is $1,000 principal amount or an integral multiple thereof) below designated, into shares of Common Stock in accordance with the terms of the Indenture referred to in this Security, and directs that the shares issuable and deliverable upon such conversion, together with any check in payment for fractional shares and any Securities representing any unconverted principal amount hereof, be issued and delivered to the registered holder hereof unless a different name has been indicated below. If shares or any portion of this Security not converted are to be issued in the name of a person other than the undersigned, the undersigned will pay all transfer taxes payable with respect thereto. Any amount required to be paid to the undersigned on account of interest (including Liquidated Damages, if any) accompanies this Security.

Dated:	Your Name:
		(Print your name exactly as it appears on the face of this Security)

Your Signature:
	(Sign exactly as your name appears on the face of this Security)

Signature Guarantee^*:

Principal amount to be converted (if less than all): $

^* Participant in a recognized Signature Guarantee Medallion Program (or other signature guarantor acceptable to the Trustee).

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Fill in for registration of shares (if to be issued) and Securities (if to be delivered) other than to and in the name of the registered holder:

(Name)

(Street Address)

(City, State and Zip Code)

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FUNDAMENTAL CHANGE REPURCHASE NOTICE

TO:	NEKTAR THERAPEUTICS
	150 Industrial Road
	San Carlos, California 94070

The undersigned registered owner of this Security hereby acknowledges receipt of a notice from Nektar Therapeutics (the “Company”) as to the occurrence of a Fundamental Change with respect to the Company and requests and instructs the Company to repay the entire principal amount of this Security, or the portion thereof (which is $1,000 principal amount or an integral multiple thereof) below designated, in accordance with the terms of the Indenture referred to in this Security, together with interest (including Liquidated Damages, if any) accrued and unpaid to, but excluding, such date, to the registered holder hereof, in cash or by delivery of shares of Common Stock as specified in the Company’s notice.

Dated:	Your Name:
		(Print your name exactly as it appears on the face of this Security)

Your Signature:
	(Sign exactly as your name appears on the face of this Security)

Signature Guarantee*:

Principal amount to be converted (if less than all): $

* Participant in a recognized Signature Guarantee Medallion Program (or other signature guarantor acceptable to the Trustee).

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SCHEDULE OF EXCHANGES OF SECURITIES²

The following exchanges, purchases, redemptions or conversions of a part of this Global Security have been made:

Date of Exchange, Purchase, Redemption or Conversion Amount of decrease in
Principal Amount of this Global Security Amount of increase in
Principal Amount of this Global Security Principal Amount of this
Global Security following such decrease (or increase) Signature of authorized
officer of Trustee

² This schedule should be included only if the Security is issued in global form.

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EX-4.2

Exhibit 4.2

REGISTRATION RIGHTS AGREEMENT

among

NEKTAR THERAPEUTICS,

MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED

LEHMAN BROTHERS INC.

GOLDMAN, SACHS & CO.

DEUTSCHE BANK SECURITIES INC.

W.R. HAMBRECHT + CO, LLC

LEERINK SWANN & COMPANY

SG COWEN & CO., LLC

and

SUNTRUST CAPITAL MARKETS, INC.

Dated as of September 28, 2005

Registration Rights Agreement (the “Agreement”), dated as of September 28, 2005 among Nektar Therapeutics, a Delaware corporation (together with any successor entity, herein referred to as the “Issuer”), Merrill Lynch, Pierce, Fenner & Smith Incorporated, Lehman Brothers Inc., Goldman, Sachs & Co., Deutsche Bank Securities Inc., W.R. Hambrecht + Co, LLC, Leerink Swann & Company, SG Cowen & Co., LLC and SunTrust Capital Markets, Inc. (collectively, the “Initial Purchasers”).

Pursuant to the Purchase Agreement, dated September 22, 2005, between the Issuer and the Initial Purchasers (the “Purchase Agreement”), the Initial Purchasers have agreed to purchase from the Issuer up to $275,000,000 ($315,000,000 if the Initial Purchasers exercise the over-allotment option in full) in aggregate principal amount of 3.25% Convertible Subordinated Notes due 2012 (the “Notes”). The Notes will be convertible into fully paid, nonassessable common stock, par value $0.0001 per share, of the Issuer (the “Common Stock”) on the terms, and subject to the conditions, set forth in the Indenture (as defined herein). To induce the Initial Purchasers to purchase the Notes, the Issuer has agreed to provide the registration rights set forth in this Agreement pursuant to Section 3(l) of the Purchase Agreement.

The parties hereby agree as follows:

1. Definitions. As used in this Agreement, the following capitalized terms shall have the following meanings:

Advice: As defined in Section 4(c)(ii) hereof.

Agreement: As defined in the preamble hereto.

Blue Sky Application: As defined in Section 6(a)(i) hereof.

Broker-Dealer: Any broker or dealer registered under the Exchange Act.

Business Day: A day other than a Saturday or Sunday or any federal holiday in the United States.

Closing Date: The date of this Agreement.

Commission: Securities and Exchange Commission.

Common Stock: As defined in the preamble hereto.

Damages Payment Date: Each Interest Payment Date.

Effectiveness Period: As defined in Section 2(a)(iii) hereof.

Effectiveness Target Date: As defined in Section 2(a)(ii) hereof.

Exchange Act: Securities Exchange Act of 1934, as amended.

Holder: A Person who owns, beneficially or otherwise, Transfer Restricted Securities.

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Indemnified Holder: As defined in Section 6(a) hereof.

Indenture: The Indenture, dated as of September 28, 2005, between the Issuer and J.P. Morgan Trust Company, National Association, as trustee (the “Trustee”), pursuant to which the Notes are to be issued, as such Indenture is amended, modified or supplemented from time to time in accordance with the terms thereof.

Initial Purchasers: As defined in the preamble hereto.

Interest Payment Date: As defined in the Indenture.

Issuer: As defined in the preamble hereto.

Liquidated Damages: As defined in Section 3(a) hereof.

Majority of Holders: Holders holding over 50% of the aggregate principal amount of Notes outstanding; provided that, for purpose of this definition, a holder of shares of Common Stock which constitute Transfer Restricted Securities and were issued upon conversion of the Notes shall be deemed to hold an aggregate principal amount of Notes (in addition to the aggregate principal amount of Notes held by such holder) equal to the aggregate principal amount of Notes converted by such Holder into such shares of Common Stock.

NASD: National Association of Securities Dealers, Inc.

Notes: As defined in the preamble hereto.

Person: An individual, partnership, corporation, unincorporated organization, trust, joint venture or a government or agency or political subdivision thereof.

Prospectus: The prospectus included in a Shelf Registration Statement, as amended or supplemented by any prospectus supplement and by all other amendments thereto, including post-effective amendments, and all material incorporated by reference into such Prospectus.

Questionnaire Deadline: As defined in Section 2(b) hereof.

Record Holder: With respect to any Damages Payment Date, each Person who is a Holder on the record date with respect to the Interest Payment Date on which such Damages Payment Date shall occur.

Registration Default: As defined in Section 3(a) hereof.

Sale Notice: As defined in Section 4(e) hereof.

Securities Act: Securities Act of 1933, as amended.

Shelf Filing Deadline: As defined in Section 2(a)(i) hereof.

Shelf Registration Statement: As defined in Section 2(a)(i) hereof.

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Suspension Period. As defined in Section 4(b)(i) hereof.

TIA: Trust Indenture Act of 1939, as in effect on the date the Indenture is qualified under the TIA.

Transfer Restricted Securities: Each Note and each share of Common Stock issued upon conversion of Notes until the earlier of:

(i) the date on which such Note or such share of Common Stock issued upon conversion has been effectively registered under the Securities Act and disposed of in accordance with the Shelf Registration Statement;

(ii) the date on which such Note or such share of Common Stock issued upon conversion is transferred in compliance with Rule 144 under the Securities Act or may be sold or transferred pursuant to Rule 144 under the Securities Act (or any other similar provision then in force); or

(iii) the date on which such Note or such share of Common Stock issued upon conversion ceases to be outstanding (whether as a result of redemption, repurchase and cancellation, conversion or otherwise).

Underwritten Registration or Underwritten Offering: A registration in which securities of the Issuer are sold to an underwriter for reoffering to the public.

2. Shelf Registration.

(a) The Issuer shall:

(i) not later than 90 days after the date hereof (the “Shelf Filing Deadline”), cause to be filed a registration statement pursuant to Rule 415 under the Securities Act (the “Shelf Registration Statement”), which Shelf Registration Statement shall provide for resales of all Transfer Restricted Securities held by Holders that have provided the information required pursuant to the terms of Section 2(b) hereof;

(ii) use its best efforts to cause the Shelf Registration Statement to be declared effective by the Commission as promptly as reasonably practicable, but in no event later than 210 days after the date hereof (the “Effectiveness Target Date”); and

(iii) use its best efforts to keep the Shelf Registration Statement continuously effective, supplemented and amended as required by the provisions of Section 4(b) hereof to the extent necessary to ensure that (A) it is available for resales by the Holders of Transfer Restricted Securities entitled to the benefit of this Agreement and (B) conforms with the requirements of this Agreement and the Securities Act and the rules and regulations of the Commission promulgated thereunder as announced from time to time for a period (the “Effectiveness Period”) of:

(A) two years following the last date of original issuance of Notes; or

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(B) such shorter period that will terminate when (x) all of the Holders of Transfer Restricted Securities are able to sell all Transfer Restricted Securities immediately without restriction pursuant to Rule 144(k) under the Securities Act or any successor rule thereto, (y) when all Transfer Restricted Securities have ceased to be outstanding (whether as a result of redemption, repurchase and cancellation, conversion or otherwise) or (z) all Transfer Restricted Securities registered under the Shelf Registration Statement have been sold.

(b) No Holder of Transfer Restricted Securities may include any of its Transfer Restricted Securities in the Shelf Registration Statement pursuant to this Agreement unless such Holder furnishes to the Issuer in writing, prior to or on the 20th Business Day after receipt of a request therefor (the “Questionnaire Deadline”), such information as the Issuer may reasonably request for use in connection with the Shelf Registration Statement or the Prospectus or preliminary Prospectus included therein and in any application to be filed with or under state securities laws. In connection with all such requests for information from Holders of Transfer Restricted Securities, the Issuer shall notify such Holders of the requirements set forth in the preceding sentence. No Holder of Transfer Restricted Securities shall be entitled to Liquidated Damages pursuant to Section 3 hereof unless such Holder shall have provided all such reasonably requested information prior to or on the Questionnaire Deadline. Each Holder as to which the Shelf Registration Statement is being effected agrees to furnish promptly to the Issuer all information required to be disclosed in order to make information previously furnished to the Issuer by such Holder not materially misleading.

3. Liquidated Damages.

(a) If:

(i) the Shelf Registration Statement is not filed with the Commission prior to or on the Shelf Filing Deadline;

(ii) the Shelf Registration Statement has not been declared effective by the Commission prior to or on the Effectiveness Target Date;

(iii) subject to the provisions of Section 4(b)(i) hereof, the Shelf Registration Statement is filed and declared effective but, during the Effectiveness Period, shall thereafter cease to be effective or fail to be usable for its intended purpose without being succeeded within five Business Days by a post-effective amendment to the Shelf Registration Statement or a report filed with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act that cures such failure and, in the case of a post-effective amendment, is itself immediately declared effective; or

(iv) prior to or on the 45^th, 60^th or 90^th day, as the case may be, of any Suspension Period, such suspension has not been terminated,

(each such event referred to in foregoing clauses (i) through (iv), a “Registration Default”), the Issuer hereby agrees to pay additional interest as liquidated damages (“Liquidated Damages”) with respect to Notes that constitute Transfer Restricted Securities, from and including the day following the Registration Default to but

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excluding the day on which the Registration Default has been cured, to each holder of such Notes, (x) with respect to the first 90-day period during which a Registration Default shall have occurred and be continuing, in an amount per year equal to an additional 0.25% of the principal amount of the Notes, and (y) with respect to the period commencing on the 91st day following the day the Registration Default shall have occurred and be continuing, in an amount per year equal to an additional 0.50% of the principal amount of the Notes; provided that in no event shall Liquidated Damages accrue at a rate per year exceeding 0.50% of the principal amount of the Notes.

(b) All accrued Liquidated Damages shall be paid in arrears to Record Holders by the Issuer on each Damages Payment Date by wire transfer of immediately available funds or by federal funds check. Following the cure of all Registration Defaults relating to any particular Note, the accrual of Liquidated Damages with respect to such Note will cease.

(c) In no event will Liquidated Damages be payable in respect of shares of Common Stock received by a holder of Notes upon conversion of such Notes.

All obligations of the Issuer set forth in this Section 3 that are outstanding with respect to any Transfer Restricted Security at the time such security ceases to be a Transfer Restricted Security shall survive until such time as all such obligations with respect to such Transfer Restricted Security shall have been satisfied in full.

The Liquidated Damages set forth above shall be the exclusive monetary remedy available to the Holders of Transfer Restricted Securities for such Registration Default.

4. Registration Procedures.

(a) In connection with the Shelf Registration Statement, the Issuer shall comply with all the provisions of Section 4(b) hereof and shall use its best efforts to effect such registration to permit the sale of the Transfer Restricted Securities being sold in accordance with the intended method or methods of distribution thereof, and pursuant thereto, shall as expeditiously as possible prepare and file with the Commission a Shelf Registration Statement relating to the registration on any appropriate form under the Securities Act.

(b) In connection with the Shelf Registration Statement and any Prospectus required by this Agreement to permit the sale or resale of Transfer Restricted Securities, the Issuer shall:

(i) Subject to any notice by the Issuer in accordance with this Section 4(b) of the existence of any fact or event of the kind described in Section 4(b)(iii)(D), use its best efforts to keep the Shelf Registration Statement continuously effective during the Effectiveness Period; upon the occurrence of any event that would cause the Shelf Registration Statement or the Prospectus contained therein (A) to contain a material misstatement or omission or (B) not be effective and usable for resale of Transfer Restricted Securities during the Effectiveness Period, the Issuer shall file promptly an appropriate amendment to the Shelf Registration Statement or a report filed with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, in the case of clause (A), correcting any such misstatement or omission, and, in the case of either clause (A) or (B), use its best efforts to cause such amendment to be declared

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effective and the Shelf Registration Statement and the related Prospectus to become usable for their intended purposes as soon as practicable thereafter. Notwithstanding the foregoing, the Issuer may suspend the effectiveness of the Shelf Registration Statement by written notice to the Holders for a period not to exceed an aggregate of 45 days in any 90-day period (each such period, a “Suspension Period”) if:

(x) an event occurs and is continuing as a result of which the Shelf Registration Statement would, in the Issuer’s reasonable judgment, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; and

(y) the Issuer reasonably determines that the disclosure of such event at such time would have a material adverse effect on the business of the Issuer (and its subsidiaries, if any, taken as a whole);

provided that in the event the disclosure relates to a previously undisclosed proposed or pending material business transaction, the disclosure of which would impede the Issuer’s ability to consummate such transaction, the Issuer may extend a Suspension Period from 45 days to 60 days; provided, however, that Suspension Periods shall not exceed an aggregate of 90 days in any 360-day period.

(ii) After the Shelf Registration Statement has been declared effective, prepare and file with the Commission (x) if permitted by the Commission to file a prospectus supplement, within 15 Business Days’ receipt of a completed questionnaire, file such supplement to the related prospectus or (y) within 30 days of receipt of a completed questionnaire, such amendments and post-effective amendments to the Shelf Registration Statement as may be necessary to keep the Shelf Registration Statement effective during the Effectiveness Period; cause the Prospectus to be supplemented by any required Prospectus supplement, and as so supplemented to be filed pursuant to Rule 424 under the Securities Act, and to comply fully with the applicable provisions of Rules 424 and 430A under the Securities Act in a timely manner; and comply with the provisions of the Securities Act with respect to the disposition of all securities covered by the Shelf Registration Statement during the applicable period in accordance with the intended method or methods of distribution by the sellers thereof set forth in the Shelf Registration Statement or supplement to the Prospectus. Notwithstanding the foregoing, the Issuer shall not be required to file any post-effective amendments to the Shelf Registration Statement until such time as the Issuer has received questionnaires from Holders of at least $10 million aggregate principal amount of Notes. In no event shall the Issuer be required to file more than one post-effective amendment per fiscal quarter.

(iii) Advise the underwriter(s), if any, and selling Holders promptly (but in any event within five Business Days) and, if requested by such Persons, to confirm such advice in writing:

(A) when the Prospectus or any Prospectus supplement or post-effective amendment has been filed, and, with respect to the Shelf Registration Statement or any post-effective amendment thereto, when the same has become effective,

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(B) of any request by the Commission for amendments to the Shelf Registration Statement or amendments or supplements to the Prospectus or for additional information relating thereto,

(C) of the issuance by the Commission of any stop order suspending the effectiveness of the Shelf Registration Statement under the Securities Act or of the suspension by any state securities commission of the qualification of the Transfer Restricted Securities for offering or sale in any jurisdiction, or the initiation of any proceeding for any of the preceding purposes, or

(D) of the existence of any fact or the happening of any event, during the Effectiveness Period, that makes any statement of a material fact made in the Shelf Registration Statement, the Prospectus, any amendment or supplement thereto, or any document incorporated by reference therein untrue, or that requires the making of any additions to or changes in the Shelf Registration Statement or the Prospectus in order to make the statements therein not misleading.

If at any time the Commission shall issue any stop order suspending the effectiveness of the Shelf Registration Statement, or any state securities commission or other regulatory authority shall issue an order suspending the qualification or exemption from qualification of the Transfer Restricted Securities under state securities or Blue Sky laws, the Issuer shall use its reasonable best efforts to obtain the withdrawal or lifting of such order at the earliest possible time.

(iv) Furnish to counsel for the Initial Purchasers, before filing with the Commission, a copy of the Shelf Registration Statement and copies of any Prospectus included therein or any amendments or supplements to the Shelf Registration Statement or Prospectus (other than documents incorporated by reference after the initial filing of the Shelf Registration Statement), which documents will be subject to the review of such counsel, for a period of at least five Business Days, and the Issuer will not file any Shelf Registration Statement or Prospectus or any amendment or supplement to the Shelf Registration Statement or Prospectus (other than documents incorporated by reference) to which such counsel shall reasonably object within five Business Days after the receipt thereof. Counsel for the Initial Purchasers shall be deemed to have reasonably objected to such filing if the Shelf Registration Statement, amendment, Prospectus or supplement, as applicable, as proposed to be filed, contains a material misstatement or omission. Notwithstanding the foregoing, the Issuer shall not be required to furnish counsel for the Initial Purchasers with any amendment or supplement to the Shelf Registration Statement or Prospectus filed solely to reflect changes to the amount of Notes held by any particular Holder at the request of such Holder or immaterial revisions to the information contained therein.

(v) Make available at reasonable times for inspection by one or more representatives of the selling Holders, designated in writing by a Majority of Holders whose Transfer Restricted Securities are included in the Shelf Registration Statement,

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any underwriter participating in any distribution pursuant to the Shelf Registration Statement, and any attorney or accountant retained by such selling Holders or any of the underwriter(s), all financial and other records, pertinent corporate documents and properties of the Issuer as shall be reasonably necessary to enable them to exercise any applicable due diligence responsibilities, and cause the Issuer’s officers, directors, managers and employees to supply all information reasonably requested by any such representative or representatives of the selling Holders, underwriter, attorney or accountant in connection with the Shelf Registration Statement after the filing thereof and before its effectiveness; provided, however, that any information designated by the Company as confidential at the time of delivery of such information shall be kept confidential by the recipient thereof.

(vi) If requested by any selling Holders or the underwriter(s), if any, promptly incorporate in the Shelf Registration Statement or Prospectus, pursuant to a supplement or post-effective amendment if necessary, such information as such selling Holders and underwriter(s), if any, may reasonably request to have included therein, including, without limitation: (1) information relating to the “Plan of Distribution” of the Transfer Restricted Securities, (2) information with respect to the principal amount of Notes or number of shares of Common Stock being sold to such underwriter(s), (3) the purchase price being paid therefor and (4) any other terms of the offering of the Transfer Restricted Securities to be sold in such offering; and make all required filings of such Prospectus supplement or post-effective amendment as soon as reasonably practicable after the Issuer is notified of the matters to be incorporated in such Prospectus supplement or post-effective amendment. Notwithstanding the foregoing, following the effective date of the Shelf Registration Statement, the Issuer shall not be required to file more than one such supplement to reflect changes in the amount of Notes held by any particular Holder at the request of such Holder in any 15-day period and in no event shall the Issuer be required to file more than one such post-effective amendment in any fiscal quarter.

(vii) Furnish to each selling Holder and each of the underwriter(s), if any, without charge, at least one copy of the Shelf Registration Statement, as first filed with the Commission, and of each amendment thereto (and any documents incorporated by reference therein or exhibits thereto (or exhibits incorporated in such exhibits by reference) as such Person may request).

(viii) Deliver to each selling Holder and each of the underwriter(s), if any, without charge, as many copies of the Prospectus (including each preliminary prospectus) and any amendment or supplement thereto as such Persons reasonably may request; subject to any notice by the Issuer in accordance with this Section 4(b) of the existence of any fact or event of the kind described in Section 4(b)(iii)(D), the Issuer hereby consents to the use of the Prospectus and any amendment or supplement thereto by each of the selling Holders and each of the underwriter(s), if any, in connection with the offering and the sale of the Transfer Restricted Securities covered by the Prospectus or any amendment or supplement thereto.

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(ix) If an underwriting agreement is entered into and the registration is an Underwritten Registration, the Issuer shall:

(A) upon request, furnish to each selling Holder and each underwriter, in such substance and scope as they may reasonably request and as are customarily made by issuers to underwriters in primary underwritten offerings, upon the date of closing of any sale of Transfer Restricted Securities in an Underwritten Registration:

(1) a certificate, dated the date of such closing, signed by the Chief Financial Officer of the Issuer confirming, as of the date thereof, the matters set forth in Section 5(g) of the Purchase Agreement and such other matters as such parties may reasonably request;

(2) opinions, each dated the date of such closing, of counsel to the Issuer covering such of the matters set forth in Sections 5(c) and 5(d) of the Purchase Agreement as are customarily covered in legal opinions to underwriters in connection with primary underwritten offerings of securities; and

(3) customary comfort letters, dated the date of such closing, from the Issuer’s independent registered public accounting firm (and from any other independent registered public accounting firm whose report is contained or incorporated by reference in the Shelf Registration Statement), in the customary form and covering matters of the type customarily covered in comfort letters to underwriters in connection with primary underwritten offerings of securities;

(B) set forth in full in the underwriting agreement, if any, indemnification provisions and procedures which provide rights no less protective than those set forth in Section 6 hereof with respect to all parties to be indemnified; and

(C) deliver such other documents and certificates as may be reasonably requested by such parties to evidence compliance with clause (A) above and with any customary conditions contained in the underwriting agreement or other agreement entered into by the selling Holders pursuant to this clause (ix).

(D) if requested by any underwriters, make appropriate officers of the Issuer available to such underwriters for meetings with prospective purchasers of the Transfer Restricted Securities and prepare and present to potential investors customary “road show” materials in a manner consistent with new issuances of securities similar to the Transfer Restricted Securities.

(x) Before any public offering of Transfer Restricted Securities, cooperate with the selling Holders, the underwriter(s), if any, and their respective counsel in connection with the registration and qualification of the Transfer Restricted Securities under the securities or Blue Sky laws of such jurisdictions as the selling Holders or underwriter(s), if any, may reasonably request and do any and all other acts or things necessary or advisable to enable the disposition in such jurisdictions of the Transfer

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Restricted Securities covered by the Shelf Registration Statement; provided, however, that the Issuer shall not be required (A) to register or qualify as a foreign corporation or a dealer of securities where it is not now so qualified or to take any action that would subject it to the service of process in any jurisdiction where it is not now so subject or (B) to subject themselves to taxation in any such jurisdiction if they are not now so subject.

(xi) Cooperate with the selling Holders and the underwriter(s), if any, to facilitate the timely preparation and delivery of certificates representing Transfer Restricted Securities to be sold and not bearing any restrictive legends (unless required by applicable securities laws); and enable such Transfer Restricted Securities to be in such denominations and registered in such names as the Holders or the underwriter(s), if any, may request at least two Business Days before any sale of Transfer Restricted Securities made by such underwriter(s).

(xii) Use its best efforts to cause the Transfer Restricted Securities covered by the Shelf Registration Statement to be registered with or approved by such other U.S. governmental agencies or authorities as may be necessary to enable the seller or sellers thereof or the underwriter(s), if any, to consummate the disposition of such Transfer Restricted Securities.

(xiii) Subject to Section 4(b)(i) hereof, if any fact or event contemplated by Section 4(b)(iii)(D) hereof shall exist or have occurred, use its reasonable best efforts to prepare a supplement or post-effective amendment to the Shelf Registration Statement or related Prospectus or any document incorporated therein by reference or file any other required document so that, as thereafter delivered to the purchasers of Transfer Restricted Securities, the Prospectus will not contain an untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading.

(xiv) Provide CUSIP numbers for all Transfer Restricted Securities not later than the effective date of the Shelf Registration Statement and provide the Trustee under the Indenture with certificates for the Notes that are in a form eligible for deposit with The Depository Trust Company.

(xv) Cooperate and assist in any filings required to be made with the NASD and in the performance of any due diligence investigation by any underwriter that is required to be retained in accordance with the rules and regulations of the NASD.

(xvi) Otherwise use its best efforts to comply with all applicable rules and regulations of the Commission and all reporting requirements under the rules and regulations of the Exchange Act.

(xvii) Cause the Indenture to be qualified under the TIA not later than the effective date of the Shelf Registration Statement required by this Agreement, and, in connection therewith, cooperate with the trustee and the holders of Notes to effect such changes to the Indenture as may be required for such Indenture to be so qualified in accordance with the terms of the TIA; and execute and use its best efforts to cause the

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trustee thereunder to execute all documents that may be required to effect such changes and all other forms and documents required to be filed with the Commission to enable such Indenture to be so qualified in a timely manner.

(xviii) Cause all Transfer Restricted Securities covered by the Shelf Registration Statement to be listed or quoted, as the case may be, on each securities exchange or automated quotation system on which similar securities issued by the Issuer are then listed or quoted.

(xix) Provide promptly to each Holder upon written request each document filed with the Commission pursuant to the requirements of Section 13 and Section 15 of the Exchange Act after the effective date of the Shelf Registration Statement.

(c) Each Holder agrees by acquisition of a Transfer Restricted Security that, upon receipt of any notice from the Issuer of the existence of any fact of the kind described in Section 4(b)(iii)(D) hereof, such Holder will, and will use its reasonable best efforts to cause any underwriter(s) in an Underwritten Offering to, forthwith discontinue disposition of Transfer Restricted Securities pursuant to the Shelf Registration Statement until:

(i) such Holder has received copies of the supplemented or amended Prospectus contemplated by Section 4(b)(xiii) hereof; or

(ii) such Holder is advised in writing (the “Advice”) by the Issuer that the use of the Prospectus may be resumed, and has received copies of any additional or supplemental filings that are incorporated by reference in the Prospectus.

If so directed by the Issuer, each Holder will deliver to the Issuer (at the Issuer’s expense) all copies, other than permanent file copies then in such Holder’s possession, of the Prospectus covering such Transfer Restricted Securities that was current at the time of receipt of such notice of suspension.

(d) Each Holder who intends to be named as a selling Holder in the Shelf Registration Statement shall furnish to the Issuer in writing, within 20 Business Days after receipt of a request therefor as set forth in a questionnaire, such information regarding such Holder and the proposed distribution by such Holder of its Transfer Restricted Securities as the Issuer may reasonably request for use in connection with the Shelf Registration Statement or Prospectus or preliminary Prospectus included therein. (The form of the questionnaire is attached hereto as Exhibit A.) Holders that do not complete the questionnaire and deliver it to the Issuer shall not be named as selling securityholders in the Prospectus or preliminary Prospectus included in the Shelf Registration Statement and therefore shall not be permitted to sell any Transfer Restricted Securities pursuant to the Shelf Registration Statement. Each Holder who intends to be named as a selling Holder in the Shelf Registration Statement shall promptly furnish to the Issuer in writing such other information as the Issuer may from time to time reasonably request in writing.

(e) Upon the effectiveness of the Shelf Registration Statement, each Holder shall notify the Issuer at least three Business Days prior to any intended distribution of Transfer Restricted Securities pursuant to the Shelf Registration Statement (a “Sale Notice”), which notice shall be effective for five Business Days. Each Holder of a Transfer Restricted Security, by

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accepting the same, agrees to hold any communication by the Company in response to a Sale Notice in confidence. Upon any transfer of Transfer Restricted Securities pursuant to the Shelf Registration Statement, each Holder shall comply with all such Holder’s obligations relating to delivery of the Prospectus under applicable securities laws. The Issuer and its representatives shall be entitled to rely on the foregoing covenant as evidence of compliance with such obligations by such Holder in connection with (i) any instruction requested of it in connection with such transfer by the Trustee of the Notes or the transfer agent of the Common Stock or (ii) any representation made by the Issuer or such representative to any governing authority, including, the Commission or NASD.

5. Registration Expenses.

(a) All expenses incident to the Issuer’s performance of or compliance with this Agreement shall be borne by the Issuer regardless of whether a Shelf Registration Statement becomes effective, including, without limitation:

(i) all registration and filing fees and expenses (including filings made by any Initial Purchasers or Holders with the NASD);

(ii) all fees and expenses of compliance with federal securities and state Blue Sky or securities laws;

(iii) all expenses of printing (including printing of Prospectuses and certificates for the Common Stock to be issued upon conversion of the Notes), messenger and delivery services and telephone charges;

(iv) all fees and disbursements of counsel to the Issuer and, subject to Section 5(b) below, the Holders of Transfer Restricted Securities;

(v) all application and filing fees in connection with listing (or authorizing for quotation) the Common Stock on a national securities exchange or automated quotation system pursuant to the requirements hereof; and

(vi) all fees and disbursements of the independent registered public accounting firm of the Issuer (including the expenses of any special audit and comfort letters required by or incident to such performance).

The Issuer shall bear its internal expenses (including, without limitation, all salaries and expenses of their officers and employees performing legal, accounting or other duties), the expenses of any annual audit and the fees and expenses of any Person, including special experts, retained by the Issuer.

(b) In connection with the Shelf Registration Statement required by this Agreement, the Issuer shall reimburse the Initial Purchasers and the Holders of Transfer Restricted Securities being registered pursuant to the Shelf Registration Statement, as applicable, for the reasonable fees and disbursements of not more than one counsel, which shall be Sidley Austin Brown & Wood LLP, or such other counsel as may be chosen by a Majority of Holders for whose benefit the Shelf Registration Statement is being prepared.

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6. Indemnification and Contribution.

(a) The Issuer shall indemnify and hold harmless each Holder, such Holder’s officers and employees and each person, if any, who controls such Holder within the meaning of the Securities Act (each, an “Indemnified Holder”), from and against any loss, claim, damage or liability, joint or several, or any action in respect thereof (including, but not limited to, any loss, claim, damage, liability or action relating to resales of the Transfer Restricted Securities), to which such Indemnified Holder may become subject, insofar as any such loss, claim, damage, liability or action arises out of, or is based upon:

(i) any untrue statement or alleged untrue statement of a material fact contained in (A) the Shelf Registration Statement or Prospectus or any amendment or supplement thereto or (B) any blue sky application or other document or any amendment or supplement thereto prepared or executed by the Issuer (or based upon written information furnished by or on behalf of the Issuer expressly for use in such blue sky application or other document or amendment on supplement) filed in any jurisdiction specifically for the purpose of qualifying any or all of the Transfer Restricted Securities under the securities law of any state or other jurisdiction (such application or document being hereinafter called a “Blue Sky Application”); or

(ii) the omission or alleged omission to state therein any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading,

and shall reimburse each Indemnified Holder promptly upon demand for any legal or other expenses reasonably incurred by such Indemnified Holder in connection with investigating or defending or preparing to defend against any such loss, claim, damage, liability or action as such expenses are incurred; provided, however, that the Issuer shall not be liable in any such case to the extent that any such loss, claim, damage, liability or action arises out of, or is based upon, any untrue statement or alleged untrue statement or omission or alleged omission made in the Shelf Registration Statement or Prospectus or amendment or supplement thereto or Blue Sky Application in reliance upon and in conformity with written information furnished to the Issuer by or on behalf of any Holder (or its related Indemnified Holder) specifically for use therein. The foregoing indemnity agreement is in addition to any liability which the Issuer may otherwise have to any Indemnified Holder.

(b) Each Holder, severally and not jointly, shall indemnify and hold harmless the Issuer, its officers and employees and each person, if any, who controls the Issuer within the meaning of the Securities Act, from and against any loss, claim, damage or liability, joint or several, or any action in respect thereof, to which the Issuer or any such officer, employee or controlling person may become subject, insofar as any such loss, claim, damage or liability or action arises out of, or is based upon:

(i) any untrue statement or alleged untrue statement of any material fact contained in the Shelf Registration Statement or Prospectus or any amendment or supplement thereto or any Blue Sky Application; or

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(ii) the omission or the alleged omission to state therein any material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading,

but in each case only to the extent that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information furnished to the Issuer by or on behalf of such Holder (or its related Indemnified Holder) specifically for use therein, and shall reimburse the Issuer and any such officer, employee or controlling person promptly upon demand for any legal or other expenses reasonably incurred by the Issuer or any such officer, employee or controlling person in connection with investigating or defending or preparing to defend against any such loss, claim, damage, liability or action as such expenses are incurred. The foregoing indemnity agreement is in addition to any liability which any Holder may otherwise have to the Issuer and any such officer, employee or controlling person.

(c) Promptly after receipt by an indemnified party under this Section 6 of notice of any claim or the commencement of any action, the indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under this Section 6, notify the indemnifying party in writing of the claim or the commencement of that action; provided, however, that the failure to notify the indemnifying party shall not relieve it from any liability which it may have under this Section 6 except to the extent it has been materially prejudiced by such failure and, provided, further, that the failure to notify the indemnifying party shall not relieve it from any liability which it may have to an indemnified party otherwise than under this Section 6. If any such claim or action shall be brought against an indemnified party, and it shall notify the indemnifying party thereof, the indemnifying party shall be entitled to participate therein and, to the extent that it wishes, jointly with any other similarly notified indemnifying party, to assume the defense thereof with counsel satisfactory to the indemnified party. After notice from the indemnifying party to the indemnified party of its election to assume the defense of such claim or action, the indemnifying party shall not be liable to the indemnified party under this Section 6 for any legal or other expenses subsequently incurred by the indemnified party in connection with the defense thereof other than reasonable costs of investigation; provided, however, that a Majority of Holders shall have the right to employ a single counsel to represent jointly a Majority of Holders and their respective officers, employees and controlling persons who may be subject to liability arising out of any claim in respect of which indemnity may be sought by a Majority of Holders against the Issuer under this Section 6, if a Majority of Holders shall have reasonably concluded that there may be one or more legal defenses available to them and their respective officers, employees and controlling persons that are different from or additional to those available to the Issuer and its officers, employees and controlling persons, the fees and expenses of a single separate counsel shall be paid by the Issuer. No indemnifying party shall:

(i) without the prior written consent of the indemnified parties (which consent shall not be unreasonably withheld) settle or compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless such settlement, compromise or consent (1) includes an unconditional release of each

14

indemnified party from all liability arising out of such claim, action, suit or proceeding and (2) does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of any indemnified party, or

(ii) be liable for any settlement of any such action effected without its written consent (which consent shall not be unreasonably withheld), but if settled with its written consent or if there be a final judgment for the plaintiff in any such action, the indemnifying party agrees to indemnify and hold harmless any indemnified party from and against any loss of liability by reason of such settlement or judgment.

(d) If the indemnification provided for in this Section 6 shall for any reason be unavailable or insufficient to hold harmless an indemnified party under Section 6(a) or 6(b) in respect of any loss, claim, damage or liability (or action in respect thereof) referred to therein, each indemnifying party shall, in lieu of indemnifying such indemnified party, contribute to the amount paid or payable by such indemnified party as a result of such loss, claim, damage or liability (or action in respect thereof):

(i) in such proportion as is appropriate to reflect the relative benefits received by the Issuer from the offering and sale of the Transfer Restricted Securities on the one hand and a Holder with respect to the sale by such Holder of the Transfer Restricted Securities on the other, or

(ii) if the allocation provided by clause (6)(d)(i) is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause 6(d)(i) but also the relative fault of the Issuer on the one hand and the Holders on the other in connection with the statements or omissions or alleged statements or alleged omissions that resulted in such loss, claim, damage or liability (or action in respect thereof), as well as any other relevant equitable considerations.

The relative benefits received by the Issuer on the one hand and a Holder on the other with respect to such offering and such sale shall be deemed to be in the same proportion as the total net proceeds from the offering of the Notes purchased under the Purchase Agreement (before deducting expenses) received by the Issuer as set forth in the table appearing in the section entitled “Plan of Distribution” in the Offering Memorandum, dated September 22, 2005, on the one hand, bear to the total proceeds received by such Holder with respect to its sale if Transfer Restricted Securities on the other.

The relative fault of the parties shall be determined by reference to whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Issuer on the one hand or the Holders on the other, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such statement or omission.

The Issuer and each Holder agree that it would not be just and equitable if the amount of contribution pursuant to this Section 6(d) were determined by pro rata allocation or by any other method of allocation that does not take into account the equitable considerations referred to in the first sentence of this paragraph (d). The amount paid or payable by an indemnified party as a

15

result of the loss, claim, damage or liability, or action in respect thereof, referred to above in this Section 6 shall be deemed to include, for purposes of this Section 6, any legal or other expenses reasonably incurred by such indemnified party in connection with investigating, or defending or preparing to defend any such litigation, investigation or proceeding by any governmental agency or body, or commenced or threatened action or claim. Notwithstanding the provisions of this Section 6, no Holder shall be required to contribute any amount in excess of the amount by which the total price at which the Transfer Restricted Securities purchased by it were resold exceeds the amount of any damages which such Holder has otherwise been required to pay by reason of any untrue or alleged untrue statement or omission or alleged omission.

No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Holders’ obligations to contribute as provided in this Section 6(d) are several and not joint.

7. Rule 144A. In the event the Issuer is not subject to Section 13 or 15(d) of the Exchange Act, the Issuer hereby agrees with each Holder, for so long as any Transfer Restricted Securities remain outstanding, to make available to any Holder or beneficial owner of Transfer Restricted Securities in connection with any sale thereof and any prospective purchaser of such Transfer Restricted Securities from such Holder or beneficial owner, the information required by Rule 144A(d)(4) under the Securities Act in order to permit resales of such Transfer Restricted Securities pursuant to Rule 144A.

8. Participation in Underwritten Registrations. No Holder may participate in any Underwritten Registration hereunder unless such Holder:

(i) agrees to sell such Holder’s Transfer Restricted Securities on the basis provided in any underwriting arrangements approved by the Persons entitled hereunder to approve such arrangements and

(ii) completes and executes all reasonable questionnaires, powers of attorney, indemnities, underwriting agreements, lock-up letters and other documents required under the terms of such underwriting arrangements.

9. Selection of Underwriters. The Holders of Transfer Restricted Securities covered by the Shelf Registration Statement who desire to do so may sell such Transfer Restricted Securities in an Underwritten Offering. In any such Underwritten Offering, the investment banker or investment bankers and manager or managers that will administer the offering will be selected by a Majority of Holders whose Transfer Restricted Securities are included in such offering; provided, that such investment bankers and managers must be reasonably satisfactory to the Issuer.

10. Miscellaneous.

(a) Remedies. The Issuer acknowledges and agrees that any failure by the Issuer to comply with its obligations under Section 2 hereof may result in material irreparable injury to the Initial Purchasers or the Holders for which there is no adequate remedy at law, that it will not be possible to measure damages for such injuries precisely and that, in the event of any such failure,

16

the Initial Purchasers or any Holder may obtain such relief as may be required to specifically enforce the Issuer’s obligations under Section 2 hereof. The Issuer further agrees to waive the defense in any action for specific performance that a remedy at law would be adequate.

(b) Adjustments Affecting Transfer Restricted Securities. The Issuer shall not, directly or indirectly, take any action with respect to the Transfer Restricted Securities as a class that would adversely affect the ability of the Holders of Transfer Restricted Securities to include such Transfer Restricted Securities in a registration undertaken pursuant to this Agreement.

(c) No Inconsistent Agreements. The Issuer will not, on or after the date of this Agreement, enter into any agreement with respect to its securities that is inconsistent with the rights granted to the Holders in this Agreement or otherwise conflicts with the provisions hereof. In addition, the Issuer shall not grant to any of its security holders (other than the holders of Transfer Restricted Securities in such capacity) the right to include any of its securities in the Shelf Registration Statement provided for in this Agreement other than the Transfer Restricted Securities. Other than the Rights Agreement, dated June 1, 2001, between the Company and Mellon Investor Services LLC., the Issuer has not previously entered into any agreement (which has not expired or been terminated) granting any registration rights with respect to its securities to any Person which rights conflict with the provisions hereof.

(d) Amendments and Waivers. This Agreement may not be amended, modified or supplemented, and waivers or consents to or departures from the provisions hereof may not be given, unless the Issuer has obtained the written consent of a Majority of Holders.

(e) Notices. All notices and other communications provided for or permitted hereunder shall be made in writing by hand-delivery, first-class mail (registered or certified, return receipt requested), telex, telecopier, or air courier guaranteeing overnight delivery:

(i) if to a Holder, at the address set forth on the records of the registrar under the Indenture or the transfer agent of the Common Stock, as the case may be; and

(ii) if to the Issuer:

Nektar Therapeutics

150 Industrial Road

San Carlos, California 94070

Attention: Secretary

With a copy to:

Cooley Godward LLP

Five Palo Alto Square

3000 El Camino Real Palo

Alto, CA 94306 Attention: John Geschke, Esq.

All such notices and communications shall be deemed to have been duly given: at the time delivered by hand, if personally delivered; five Business Days after being deposited in the

17

mail, postage prepaid, if mailed; when answered back, if telexed; when receipt acknowledged, if telecopied; and on the next Business Day, if timely delivered to an air courier guaranteeing overnight delivery.

(f) Successors and Assigns. This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties, including without limitation and without the need for an express assignment, subsequent Holders of Transfer Restricted Securities; provided, however, that (i) this Agreement shall not inure to the benefit of or be binding upon a successor or assign of a Holder unless and to the extent such successor or assign acquired Transfer Restricted Securities from such Holder and (ii) nothing contained herein shall be deemed to permit any assignment, transfer or other disposition of Transfer Restricted Securities in violation of the terms of the Purchase Agreement or the Indenture. If any transferee of any Holder shall acquire Transfer Restricted Securities, in any manner, whether by operation of law or otherwise, such Transfer Restricted Securities shall be held subject to all of the terms of this Agreement, and by taking and holding such Transfer Restricted Securities such person shall be conclusively deemed to have agreed to be bound by and to perform all of the terms and provisions of this Agreement.

(g) Counterparts. This Agreement may be executed in any number of counterparts and by the parties hereto in separate counterparts, each of which when so executed shall be deemed to be an original and all of which taken together shall constitute one and the same agreement.

(h) Securities Held by the Issuer or Their Affiliates. Whenever the consent or approval of Holders of a specified percentage of Transfer Restricted Securities is required hereunder, Transfer Restricted Securities held by the Issuer or its “affiliates” (as such term is defined in Rule 405 under the Securities Act) shall not be counted in determining whether such consent or approval was given by the Holders of such required percentage.

(i) Headings. The headings in this Agreement are for convenience of reference only and shall not limit or otherwise affect the meaning hereof.

(j) Governing Law. This Agreement shall be governed by, and construed in accordance with, the law of the State of New York, without regard to conflict of laws principles thereof.

(k) Severability. If any one or more of the provisions contained herein, or the application thereof in any circumstance, is held invalid, illegal or unenforceable, the validity, legality and enforceability of any such provision in every other respect and of the remaining provisions contained herein shall not be affected or impaired thereby.

(l) Entire Agreement. This Agreement is intended by the parties as a final expression of their agreement and intended to be a complete and exclusive statement of the agreement and understanding of the parties hereto in respect of the subject matter contained herein. There are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein with respect to the registration rights granted by the Issuer with respect to the Transfer Restricted Securities. This Agreement supersedes all prior agreements and understandings between the parties with respect to such subject matter.

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IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first written above.

NEKTAR THERAPEUTICS
By:	/s/ Ajit Gill
Name:	Ajit Gill
Title:	Chief Executive Officer

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MERRILL LYNCH, PIERCE, FENNER & SMITH                         INCORPORATED
By:	/s/ Saira Ramasastry
	Authorized Representative
LEHMAN BROTHERS INC.
By:	/s/ David A. Galper
Name:	David A. Galper
Title:	Vice President
For themselves and as representatives of the other Initial Purchasers

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Exhibit A

NEKTAR THERAPEUTICS

THIS NOTICE AND QUESTIONNAIRE MUST BE RETURNED TO NEKTAR THERAPEUTICS (AT THE ADDRESS LISTED BELOW) ON OR BEFORE THE 20^TH BUSINESS DAY FOLLOWING DELIVERY OF THE NOTICE AND QUESTIONNAIRE BY NEKTAR THERAPEUTICS TO THE TRUSTEE AND THE REGISTERED HOLDER IN ORDER TO BE NAMED IN THE SHELF REGISTRATION STATEMENT REFERRED TO BELOW AT THE TIME OF ITS EFFECTIVENESS.

Form of Selling Securityholder Notice and Questionnaire

The undersigned beneficial holder of 3.25% Convertible Subordinated Notes due 2012 (the “Notes”) of Nektar Therapeutics (the “Company”), or shares of common stock, par value $0.0001 per share, of the Company issuable upon conversion thereof (the “Conversion Shares” and together with the Notes, the “Transfer Restricted Securities”) understands that the Company has filed or intends to file with the Securities and Exchange Commission (the “SEC”) a registration statement on Form S-3 (the “Shelf Registration Statement”), for the registration and resale under Rule 415 of the Securities Act of 1933, as amended (the “Securities Act”), of the Transfer Restricted Securities in accordance with the terms of the Registration Rights Agreement, dated as of September 28, 2005 (the “Registration Rights Agreement”) among the Company and the initial purchasers named therein. A copy of the Registration Rights Agreement is available from the Company upon request at the address set forth below. All capitalized terms not otherwise defined herein have the meaning ascribed thereto in the Registration Rights Agreement.

Each beneficial owner of Transfer Restricted Securities is entitled to the benefits of the Registration Rights Agreement. In order to sell or otherwise dispose of any Transfer Restricted Securities pursuant to the Shelf Registration Statement, a beneficial owner of Transfer Restricted Securities generally will be required to be named as a selling securityholder in the related prospectus, deliver a prospectus to purchasers of Transfer Restricted Securities and be bound by those provisions of the Registration Rights Agreement applicable to such beneficial owner (including certain indemnification provisions, as described below). The Company will distribute this questionnaire to each holder. Beneficial owners must complete and deliver the Notice and Questionnaire within 20 business days of receipt so that such beneficial owners may be named as selling securityholders in the related prospectus at the time of effectiveness. Upon receipt of a completed Notice and Questionnaire from a beneficial owner following the effectiveness of the Shelf Registration Statement, the Company will, (i) if permitted by the SEC to file a prospectus supplement, file such supplements to the related prospectus within 15 business days’ receipt of the completed questionnaire and (2) within 30 days’ receipt of such completed questionnaire, file such amendments to the Shelf Registration Statement as are necessary to permit such holder to be named as a selling securityholder in such prospectus; provided that if an amendment to the Shelf Registration Statement is required, the Company shall not be obligated to file such amendment unless the Company shall have received Notice and Questionnaires from holders of Transfer Restricted Securities holding an aggregate of at least $10,000,000 principal amount of

1

Notes and in no event shall the Company be required to file more than one such amendment for all such holders in any one fiscal quarter. The Company has agreed to pay additional interest pursuant to the Registration Rights Agreement under certain circumstances as set forth therein.

Certain legal consequences arise from being named as a selling securityholder in the Shelf Registration Statement and the related prospectus. Accordingly, holders and beneficial owners of Transfer Restricted Securities are advised to consult their own securities law counsel regarding the consequences of being named or not being named as a selling securityholder in the Shelf Registration Statement and the related prospectus.

Notice

The undersigned beneficial owner (the “Selling Securityholder”) of Transfer Restricted Securities hereby gives notice to the Company of its intention to sell or otherwise dispose of Transfer Restricted Securities beneficially owned by it and listed below in Item 3 (unless otherwise specified under Item 3) pursuant to the Shelf Registration Statement. The undersigned, by signing and returning this Notice and Questionnaire, understands that it will be bound by the terms and conditions of this Notice and Questionnaire and the Registration Rights Agreement.

Pursuant to the Registration Rights Agreement, the undersigned has agreed to indemnify and hold harmless the Company, the Company’s directors, officers and employees and each person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act, from and against certain losses arising in connection with statements concerning the undersigned made in the Shelf Registration Statement or the related prospectus in reliance upon the information provided in this Notice and Questionnaire.

The undersigned hereby provides the following information to the Issuer and represents and warrants that such information is accurate and complete:

Questionnaire

1. (a)     Full legal name of Selling Securityholder:

______________________________________________________________________________________________________________________________

(b) Full legal name of registered holder (if not the same as (a) above) through which Transfer Restricted Securities listed in (3) below are held:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

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(c) Full legal name of DTC participant (if applicable and if not the same as (b) above) through which Transfer Restricted Securities listed in (3) are held:

______________________________________________________________________________________________________________________________

2. Address for notices to Selling Securityholders:

Telephone:                                                                                                                                                                             

Fax:                                                                                                                                                                                           

Email:                                                                                                                                                                                     

Contact Person:                                                                                                                                                                    

3. Beneficial ownership of Securities:

(a) Type and Principal Amount of Transfer Restricted Securities beneficially owned:

______________________________________________________________________________________________________________________________

(b) CUSIP No(s). of such Transfer Restricted Securities beneficially owned:

______________________________________________________________________________________________________________________________

(c) Were the securities listed in Item 3(a) above acquired in the ordinary course of business?

¨    Yes.

¨    No.

______________________________________________________________________________________________________________________________

(d) At the time of the purchase of the securities listed in Item 3(a) above, did the Selling Securityholder have any agreements or understandings, directly or indirectly, with any person to distribute the securities?

¨    Yes.

¨    No.

(e) If your response to Item 3(d) above is yes, please describe such agreements or understandings:

______________________________________________________________________________________________________________________________

3

4. Beneficial ownership of other Company’s securities owned by the Selling Securityholder:

Except as set forth below in this Item 4, the undersigned is not the beneficial or registered owner of any securities of the Company other than the Transfer Restricted Securities listed above in Item 3 (“Other Securities”).

(a) Type and amount of Other Securities beneficially owned by the Selling Securityholder:

______________________________________________________________________________________________________________________________

(b) CUSIP No(s). of such Other Securities beneficially owned:

______________________________________________________________________________________________________________________________

5. (a)    Broker-Dealer Status:

        Is the Selling Securityholder a registered broker-dealer?

¨    Yes.

¨    No.

Note that in general we will be required to identify any registered broker-dealer as an underwriter in the prospectus.

Is so, please answer the remaining questions in this section.

(i) If the undersigned is a registered broker-dealer, please indicate whether the undersigned purchased its Transfer Restricted Securities for investment or acquired them as transaction-based compensation for investment banking or similar services.

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

If the undersigned is a registered broker-dealer and received its Transfer Restricted Securities other than as transaction-based compensation, the Company is required to identify you as an underwriter in the Shelf Registration Statement and related Prospectus.

(ii) Except as set forth below, if the undersigned is a registered broker-dealer, the undersigned does not plan to make a market in the Transfer Restricted Securities. If the undersigned plans to make a market in the Transfer Restricted Securities, please indicate whether you plan to use the prospectus relating to the Transfer Restricted Securities as a market-making prospectus.

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______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

(b) Affiliation with Broker-Dealers:

Is the Selling Securityholder an affiliate of a registered broker-dealer? For purposes of this Item 5(b) an “affiliate” of a specified person or entity means a person or entity that directly, or indirectly through one or more intermediaries, controls or is controlled by, or is under common control with the person or entity specified.

¨    Yes.

¨    No.

If so, please answer the remaining questions in this section.

(i) Please describe the affiliation between the Selling Securityholder and any registered broker-dealers:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

(ii) If the Notes were purchased by the Selling Securityholder other than in the ordinary course of business, please describe the circumstances:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

(iii) If the Selling Securityholder, at the time of its purchase of Transfer Restricted Securities, has had any agreements or understandings, directly or indirectly, with any person to distribute the Transfer Restricted Securities, please describe such agreements or understandings:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

5

______________________________________________________________________________________________________________________________

Note that if the Selling Securityholder is an affiliate of a broker-dealer and did not purchase its Notes in the ordinary course of business or at the time of the purchase had any agreements or understandings, directly or indirectly, to distribute the securities, we much identify the Selling Securityholder as an underwriter in the prospectus.

6. Relationship with the Company

Except as set forth below, neither the undersigned nor any of its affiliates, officers, directors or principal equity holders (5% or more) has held any position or has had any other material relationship with the Company (or its predecessors or affiliates) during the past three years.

State any exceptions here:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

7. Nature of Beneficial Ownership. The purpose of this question is to identify the ultimate natural person(s) or publicly held entity that exercise(s) sole or shared voting or dispositive power over the Transfer Restricted Securities.

(a) Is the Selling Securityholder a natural person?

¨    Yes.

¨    No.

(b) Is the Selling Securityholder required to file, or is it a wholly-owned subsidiary of a company that is required to file, periodic and other reports (for example, Forms 10-K, 10-Q, 8-K) with the SEC pursuant to Section 13(a) and 15(d) of the Exchange Act?

¨    Yes.

¨    No.

(c) If you answered “No” to both questions above, please identify the controlling person(s) of the Selling Secuirtyholder (the “Controlling Entity”). If the Controlling Entity is not a natural person or a publicly held entity, please identify each controlling person(s) of such Controlling Entity. This process should be repeated until you reach natural persons or a publicly held entity that exercise sole or shared voting or dispositive power over the Transfer Restricted Securities.

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______________________________________________________________________________________________________________________________

If you need more space for this response, please attach additional sheets of paper. Please be sure to indicate your name and the number of the item being responded to on each such additional sheet of paper, and to sign each such additional sheet of paper before attaching it to this Questionnaire. Please note that you may be asked to answer additional questions depending on your responses to the above questions.

8. Plan of Distribution:

Except as set forth below, the undersigned (including its donees or pledgees) intends to distribute the Transfer Restricted Securities listed above in Item 3 pursuant to the Shelf Registration Statement only as follows (if at all): Such Transfer Restricted Securities may be sold from time to time directly by the undersigned or, alternatively, through underwriters, broker-dealers or agents. If the Transfer Restricted Securities are sold through underwriters or broker-dealers, the Selling Securityholder will be responsible for underwriting discounts or commissions or agent’s commissions. Such Transfer Restricted Securities may be sold in one or more transactions at fixed prices, at prevailing market prices at the time of sale, at varying prices determined at the time of sale, or at negotiated prices. Such sales may be effected in transactions (which may involve crosses or block transactions), (i) on any national securities exchange or quotation service on which the Transfer Restricted Securities may be listed or quoted at the time of sale, (ii) in the over-the-counter market or, (iii) in transactions otherwise than on such exchanges or services or in the over-the-counter market.

State any exceptions here:

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

Note: In no event will such method(s) of distribution take the form of an underwritten offering of the Transfer Restricted Securities without the prior agreement of the Issuer.

9. Securities Received From Named Selling Securityholder:

Did the Selling Securityholder receive its Transfer Restricted Securities listed above in Item 3 as a transferee from selling securityholder(s) previously identified in the Shelf Registration Statement?

¨    Yes.

¨    No.

If so, please answer the remaining questions in this section.

7

(i) Did the Selling Securityholder receive such Transfer Restricted Securities listed above in Item 3 from the named selling securityholder(s) prior to the effectiveness of the Shelf Registration Statement?

¨    Yes.

¨    No.

(ii) Identify below the name(s) of the selling securityholder(s) from whom the Selling Securityholder received the Transfer Restricted Securities listed above in Item 3 and the date on which such securities were received.

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________

The undersigned acknowledges that it understands its obligation to comply with the provisions of the Exchange Act and the rules and regulations thereunder relating to stock manipulation, particularly Regulation M thereunder (or any successor rules or regulations), in connection with any offering of Transfer Restricted Securities pursuant to the Shelf Registration Statement.

The undersigned agrees that neither it nor any person acting on its behalf will engage in any transaction in violation of such provisions.

The Selling Securityholder hereby acknowledges its obligations under the Registration Rights Agreement, including, without limitation, its obligations to indemnify and hold harmless certain persons and to comply with its prospectus delivery requirements as set forth therein.

Pursuant to the Registration Rights Agreement, the Company has agreed under certain circumstances to indemnify the Selling Securityholders against certain liabilities.

In accordance with the undersigned’s obligation under the Registration Rights Agreement to provide such information as may be required by law for inclusion in the Shelf Registration Statement, the undersigned agrees to promptly notify the Issuer of any inaccuracies or changes in the information provided herein that may occur subsequent to the date hereof at any time while the Shelf Registration Statement remains effective. All notices hereunder and pursuant to the Registration Rights Agreement shall be made in writing at the address set forth below.

In the event that the undersigned transfers all or any portion of the Transfer Restricted Securities listed in Item 3 above after the date on which such information is provided to the Company, the undersigned agrees to notify the transferee(s) at the time of transfer of its rights and obligations under this Notice and Questionnaire and the Registration Rights Agreement.

By signing below, the undersigned consents to the disclosure of the information contained herein in its answers to Items 1 through 8 above and the inclusion of such information

8

in the Shelf Registration Statement and the related prospectus. The undersigned understands that such information will be relied upon by the Company in connection with the preparation or amendment of the Shelf Registration Statement and the related prospectus.

Once this Notice and Questionnaire is executed by the undersigned beneficial holder and received by the Company, the terms of this Notice and Questionnaire, and the representations and warranties contained herein, shall be binding on, shall inure to the benefit of and shall be enforceable by the respective successors, heirs, personal representatives and assigns of the Company and the undersigned beneficial holder. This Notice and Questionnaire shall be governed in all respects by the laws of the State of New York.

9

IN WITNESS WHEREOF, the undersigned, by authority duly given, has caused this Notice and Questionnaire to be executed and delivered either in person or by its duly authorized agent.

Beneficial Owner:

By:

Name:

Title:

Dated:

PLEASE RETURN THE COMPLETED AND EXECUTED NOTICE AND QUESTIONNAIRE TO NEKTAR THERAPEUTICS NO LATER THAN THE 20^TH BUSINESS DAY AFTER THIS NOTICE AND QUESTIONNAIRE HAS BEEN DELIVERED TO THE TRUSTEE AND THE REGISTERED HOLDER AT:

                                                     Nektar Therapeutics

                                                     150 Industrial Road

                                                     San Carlos, California 94070

                                                     Attention: Secretary

                                                     Telephone: (650) 631-3100

                                                     Facsimile: (650) 631-3150

10

EX-10.1

Exhibit 10.1

NEKTAR THERAPEUTICS

(a Delaware corporation)

$275,000,000

3.25% Convertible Subordinated Notes due 2012

PURCHASE AGREEMENT

September 22, 2005

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

4 World Financial Center

New York, New York 10080

Lehman Brothers Inc.

745 Seventh Avenue

New York, New York 10019

    As Representatives of the several Initial Purchasers

Ladies and Gentlemen:

Nektar Therapeutics, a Delaware corporation (the “Company”), confirms its agreement with each of the Initial Purchasers named in Schedule 1 hereto (collectively, the “Initial Purchasers,” which term shall also include any initial purchaser substituted as hereinafter provided in Section 8 hereof), for whom Merrill Lynch, Pierce, Fenner & Smith Incorporated and Lehman Brothers Inc. are acting as representatives (in such capacity, the “Representatives”), with respect to the issue and sale by the Company and the purchase by the Initial Purchasers, acting severally and not jointly, of the respective principal amounts set forth in said Schedule 1 of $275,000,000 aggregate principal amount of the Company’s 3.25% Convertible Subordinated Notes due 2012 (the “Firm Notes”), and with respect to the grant by the Company to the Initial Purchasers, acting severally and not jointly, of the option described in Section 2(b) hereof (the “Option”) to purchase all or any part of an additional $40,000,000 principal amount of the Company’s 3.25% Convertible Subordinated Notes due 2012 (the “Optional Notes” and, together with the Firm Notes, the “Notes”).

The Notes will be convertible into fully paid, nonassessable shares of common stock of the Company, par value $0.0001 per share (the “Common Stock”), on the terms, and subject to the conditions, set forth in the Indenture (as defined below). As used herein, “Conversion Shares” means the shares of Common Stock into which the Notes are convertible. The Notes will be issued pursuant to an Indenture (the “Indenture”) to be dated as of the First Delivery Date (as defined in Section 2(a)), between the Company and J.P. Morgan Trust Company, National Association, as trustee (the “Trustee”).

The Notes will be offered and sold without being registered under the Securities Act of 1933, as amended (the “Securities Act”), in reliance on exemptions therefrom. The Company has prepared and delivered to each Initial Purchaser copies of a preliminary offering memorandum dated September 21, 2005 (the “Preliminary Offering Memorandum”) and has prepared and will deliver to each Initial Purchaser, on the date hereof or the next succeeding day, copies of a final offering memorandum dated September 22, 2005 (the “Final Offering Memorandum”), each for use by such Initial Purchaser in connection with its solicitation of purchases of, or offering of, the Notes. “Offering Memorandum” means, with respect to any date or time referred to in this Agreement, the most recent offering memorandum (whether the Preliminary Offering Memorandum or the Final Offering Memorandum, or any amendment or supplement to either such document) which has been prepared and delivered by the Company to the Initial Purchasers in connection with their solicitation of purchases of, or offering of, the Notes. As used herein, the terms “Preliminary Offering Memorandum,” “Final Offering Memorandum” and “Offering Memorandum” shall include in each case the documents incorporated by reference therein.

Holders of the Notes (including the Initial Purchasers and their direct and indirect transferees) will be entitled to the benefits of a Resale Registration Rights Agreement, dated the First Delivery Date, between the Company and the Initial Purchasers (the “Registration Rights Agreement”), pursuant to which the Company will agree to file with the Securities and Exchange Commission (the “Commission”) a shelf registration statement pursuant to Rule 415 under the Securities Act (the “Registration Statement”) covering the resale of the Notes and the Conversion Shares, and to use its best efforts to cause the Registration Statement to be declared effective.

This Agreement, the Indenture, the Notes and the Registration Rights Agreement are referred to herein collectively as the “Operative Documents.”

Capitalized terms used herein without definition have the respective meanings specified in the Offering Memorandum.

1. Representations, Warranties and Agreements of the Company. The Company represents and warrants to each Initial Purchaser as of the date hereof and as of each Delivery Date (as defined in Section 2(b)) and agrees with each Initial Purchaser, as follows:

(a) Each of the Preliminary Offering Memorandum and the Offering Memorandum, did not as of its respective date, and the Offering Memorandum will not as of a Delivery Date (as defined in Section 2(b)), contain any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided that the Company makes no representation or warranty as to information contained in or omitted from the Preliminary

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Offering Memorandum or the Offering Memorandum in reliance upon and in conformity with written information furnished to the Company by or on the behalf of any Initial Purchaser through the Representatives specifically for inclusion therein.

(b) Assuming the accuracy of the representations and warranties of the Initial Purchasers contained in Section 6 and their compliance with the agreements set forth therein, it is not necessary, in connection with the issuance and sale of the Notes to the Initial Purchasers and the offer, resale and delivery of the Notes by the Initial Purchasers in the manner contemplated by this Agreement, the Indenture, the Registration Rights Agreement and the Offering Memorandum, to register the Notes or the Conversion Shares under the Securities Act or to qualify the Indenture under the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”).

(c) The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Delaware, is duly qualified to do business and is in good standing as a foreign corporation in each jurisdiction in which its ownership or lease of property or the conduct of its businesses requires such qualification (except for where the failure to be so qualified would not have a material adverse effect on the affairs, management, business, properties, financial condition, results of operations or prospects of the Company and its subsidiaries considered as one enterprise, whether or not arising in the ordinary course of business (a “Material Adverse Effect”)), and has all power and authority necessary to own or hold its properties and to conduct the businesses in which it is engaged, as described in the Offering Memorandum.

(d) Each subsidiary of the Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of its jurisdiction of incorporation, is duly qualified to do business and is in good standing as a foreign corporation in each jurisdiction in which its ownership or lease of property or the conduct of its businesses requires such qualification (except for where the failure to be so qualified would not have a Material Adverse Effect) and has all power and authority necessary to own or hold its properties and to conduct the businesses in which it is engaged, as described in the Offering Memorandum; except as otherwise disclosed in the Offering Memorandum, all of the issued and outstanding capital stock of each subsidiary of the Company has been duly authorized and validly issued, is fully paid and non-assessable and is owned by the Company, directly or through subsidiaries, free and clear of any security interest, mortgage, pledge, lien, encumbrance, claim or equity; none of the outstanding shares of capital stock of any such subsidiary was issued in violation of the preemptive or similar rights of any securityholder of such subsidiary.

(e) The authorized, issued and outstanding capital stock of the Company, as of June 30, 2005, is as set forth in the Offering Memorandum under the column entitled “Actual” under the caption “Capitalization,” and all of the issued and outstanding shares of capital stock of the Company have been duly

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authorized and validly issued, and are fully paid and nonassessable; none of the outstanding shares of capital stock of the Company was issued in violation of the preemptive or other similar rights of any securityholder of the Company; the capital stock of the Company conforms to the description thereof contained in the Offering Memorandum and such description conforms to the rights set forth in the instruments defining the same; the Conversion Shares, which are authorized on the date hereof, have been duly authorized and reserved for issuance upon conversion of the Notes by all necessary corporate action and are free of preemptive rights; all Conversion Shares, when so issued and delivered upon such conversion in accordance with the terms of the Indenture, will be duly authorized and validly issued, fully paid and nonassessable and free and clear of all liens, encumbrances, equities or claims; and the issuance of such Conversion Shares upon such conversion will not be subject to the preemptive or other similar rights of any securityholder of the Company.

(f) The execution, delivery and performance of the Operative Documents by the Company and the issuance of the Notes and the Conversion Shares and the consummation of the transactions contemplated hereby and thereby will not (x) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which it or any of them are bound or to which any of the properties or assets of the Company or any subsidiary is subject, (y) result in any violation of the provisions of the certificate of incorporation or bylaws of the Company or any of its subsidiaries or (z) result in any violation of any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any subsidiary or any of their properties or assets; and except (i) with respect to the transactions contemplated by the Registration Rights Agreement, as may be required under the Securities Act, the Trust Indenture Act and the rules and regulations promulgated thereunder and (ii) as required by the state securities or “blue sky” laws, no consent, approval, authorization or order of, or filing or registration with, any such court or governmental agency or body is required for the execution, delivery and performance of the Operative Documents by the Company, and the consummation of the transactions contemplated hereby and thereby.

(g) The Company has all necessary corporate right, power and authority to execute and deliver this Agreement and perform its obligations hereunder; and this Agreement has been duly authorized, executed and delivered by the Company and the transactions contemplated hereby have been duly authorized by the Company.

(h) The Company has all necessary corporate right, power and authority to execute and deliver the Indenture and perform its obligations thereunder; the Indenture has been duly authorized by the Company, and upon the effectiveness of the Registration Statement, will be qualified under the Trust

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Indenture Act; on the First Delivery Date, the Indenture will have been duly executed and delivered by the Company and, assuming due authorization, execution and delivery of the Indenture by the Trustee, will constitute a legally valid and binding agreement of the Company enforceable against the Company in accordance with its terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, subject to general principles of equity and to limitations on availability of equitable relief, including specific performance (whether considered in a proceeding in equity or at law) and an implied covenant of good faith and fair dealing; and the Indenture conforms in all material respects to the description thereof contained in the Offering Memorandum.

(i) The Company has all necessary corporate right, power and authority to execute and deliver the Registration Rights Agreement and perform its obligations thereunder; the Registration Rights Agreement and the transactions contemplated thereby have been duly authorized by the Company; when the Registration Rights Agreement is duly executed and delivered by the Company (assuming due authorization, execution and delivery by the Initial Purchasers), it will be a legally valid and binding agreement of the Company enforceable against the Company in accordance with its terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, subject to general principles of equity and to limitations on availability of equitable relief, including specific performance (whether considered in a proceeding in equity or at law) and an implied covenant of good faith and fair dealing, and except with respect to the rights of indemnification and contribution thereunder, where enforcement thereof may be limited by federal or state securities laws or the policies underlying such laws; and the Registration Rights Agreement conforms in all material respects to the description thereof contained in the Offering Memorandum.

(j) The Company has all necessary corporate right, power and authority to execute, issue and deliver the Notes and perform its obligations thereunder; the Notes have been duly authorized by the Company; when the Notes are executed, authenticated and issued in accordance with the terms of the Indenture and delivered to and paid for by the Initial Purchasers pursuant to this Agreement on the respective Delivery Date (assuming due authentication of the Notes by the Trustee), such Notes will constitute legally valid and binding obligations of the Company, entitled to the benefits of the Indenture and enforceable against the Company in accordance with their terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, subject to general principles of equity and to limitations on availability of equitable relief, including specific performance (whether considered in a proceeding in equity or at law) and an implied covenant of good faith and fair dealing; and the Notes conform in all material respects to the description thereof contained in the Offering Memorandum.

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(k) Except for the Rights Agreement, dated June 1, 2001, between the Company and Mellon Investor Services LLC., there are no contracts, agreements or understandings between the Company and any person granting such person the right (other than rights which have been waived or satisfied) to require the Company to file a registration statement under the Securities Act with respect to any securities of the Company owned or to be owned by such person or to require the Company to include such securities in any securities being registered pursuant to any registration statement filed by the Company under the Securities Act.

(l) Neither the Company nor any of its subsidiaries has sustained, since the date of the latest audited financial statements included in the Offering Memorandum, any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree; and, since such date, there has not been any change in the capital stock or long-term debt of the Company or any of its subsidiaries (except for (i) any grants under the Company’s employee stock plans in accordance with the terms of such plans as described in the Offering Memorandum, or other shares of Common Stock (or rights to receive Common Stock) issued to service providers to the Company in the ordinary course of business (“Authorized Grants”), (ii) the issuance of common stock upon conversion of outstanding convertible securities or exercise of any outstanding rights to acquire common stock pursuant to the Company’s employee stock plans as described in the Offering Memorandum (“Authorized Issuances”) and (iii) indebtedness incurred by the Company’s subsidiaries pursuant to outstanding lines of credit or other debt facilities not to exceed $10.0 million), or any material adverse change in or affecting the affairs, management, business, properties, financial condition, stockholders’ equity, results of operations or prospects of the Company and its subsidiaries considered as one enterprise, whether or not arising in the ordinary course of business, except in all cases as described in the Offering Memorandum.

(m) The financial statements of the Company and its consolidated subsidiaries (including the related notes and supporting schedules) included in the Offering Memorandum present fairly the financial condition and results of operations of the Company and its consolidated subsidiaries, at the dates and for the periods indicated, and have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods involved. The selected and summary financial information, if any, included in the Offering Memorandum presents fairly the information shown therein and has been compiled on a basis consistent with that of the audited financial statements included in the Offering Memorandum.

(n) Ernst & Young LLP, who certified the financial statements and supporting schedules, if any, of the Company included in the Offering Memorandum, are an independent registered public accounting firm as required by the Securities Act and the rules and regulations promulgated thereunder.

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(o) The Company and its subsidiaries have good and marketable title in fee simple to all real property and good and marketable title to all personal property owned by them, in each case free and clear of all liens, encumbrances, security interests, claims and defects, except such as are described in the Offering Memorandum or such as do not, singly or in the aggregate, materially affect the value of such property and do not interfere with the use made and proposed to be made of such property by the Company or any of its subsidiaries; and all real property and personal property held under lease or sublease by the Company and its subsidiaries is held by them under valid, subsisting and enforceable leases (or subleases, as the case may be) in full force and effect, with such exceptions as are not material and do not interfere with the use made and proposed to be made of such property by the Company or any of its subsidiaries. Neither the Company nor any of its subsidiaries have notice of any material claim of any sort that has been asserted by anyone adverse to the rights of the Company or any of its subsidiaries under any of the leases or subleases mentioned above, or affecting or questioning the rights of the Company or such subsidiary to the continued possession of the leased or subleased premises under any such lease or sublease.

(p) The Company and its subsidiaries carry, or are covered by, insurance as is customary for companies similarly situated and engaged in similar businesses in similar industries.

(q) The Company and its subsidiaries own, or possess adequate rights to use, all material trademarks, service marks, trade names, trademark registrations, service mark registrations, copyrights and licenses necessary for the conduct of their business, and have no reason to believe that the conduct of their business will conflict with, and have not received any notice of any claim of conflict with, any such rights of others.

(r) The Company and its subsidiaries own, or possess adequate rights to use, all material patents necessary for the conduct of their business. Except as set forth in the Offering Memorandum, no valid U.S. patent is, or to the knowledge of the Company would be, infringed by the activities of the Company or any of its subsidiaries in the manufacture, use, offer for sale or sale of any product or component thereof as described in the Offering Memorandum. The patent applications (the “Patent Applications”) filed by or on behalf of the Company and its subsidiaries described in the Offering Memorandum have been properly prepared and filed on behalf of the Company and its subsidiaries; each of the Patent Applications and patents (the “Patents”) described in the Offering Memorandum is assigned or licensed to the Company or its subsidiaries, and, except as set forth or contemplated in the Offering Memorandum, no other entity or individual has any right or claim in any Patent, Patent Application or any patent to be issued therefrom; and, to the knowledge of the Company, each of the Patent Applications discloses potentially patentable subject matter. There are no

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actions, suits or judicial proceedings pending relating to patents or proprietary information to which the Company or any of its subsidiaries is a party or of which any property of the Company or any of its subsidiaries is subject, and, to the knowledge of the Company, no actions, suits or judicial proceedings are threatened by governmental authorities or, except as set forth or contemplated in the Offering Memorandum, or as could not individually or in the aggregate be reasonably expected to have a Material Adverse Effect. The Company is not aware of, except as set forth or contemplated in the Offering Memorandum, any claim by others that the Company or any of its subsidiaries is infringing or otherwise violating any patents or other intellectual property rights of others and is not aware of any rights of third parties to any of the Company’s or any of its subsidiaries’ Patent Applications, licensed Patents or licenses which could affect materially the use thereof by the Company or any of its subsidiaries. Except as set forth in the Offering Memorandum, the Company and its subsidiaries own or possess sufficient licenses or other rights to use all patents, trade secrets, technology and know-how necessary to conduct their business as described in the Offering Memorandum.

(s) Except as disclosed in the Offering Memorandum, the Company and its subsidiaries have filed with the Food and Drug Administration (the “FDA”) and the California Food and Drug Branch (“CFDB”) for and received approval of all registrations, applications, licenses, requests for exemptions, permits and other regulatory authorizations necessary to conduct their business as it is described in the Offering Memorandum; the Company and its subsidiaries are in material compliance with all such registrations, applications, licenses, requests for exemptions, permits and other regulatory authorizations, and all applicable FDA and CFDB rules and regulations, guidelines and policies, including but not limited to, applicable FDA and CFDB rules, regulations and policies relating to current good manufacturing practice (“CGMP”) and current good laboratory practice (“CGLP”); the Company has no reason to believe that any party granting any such registration, application, license, request for exemption, permit or other authorization is considering limiting, suspending or revoking the same and knows of no basis for any such limitation, suspension or revocation.

(t) The human clinical trials, animal studies and other preclinical tests conducted by the Company or any subsidiary or in which the Company or any subsidiary has participated that are described in the Offering Memorandum or the results of which are referred to in the Offering Memorandum, and, to the knowledge of the Company, such studies and tests conducted on behalf of the Company or any of its subsidiaries, were and, if still pending, are being conducted in accordance with commonly used or appropriate experimental protocols, procedures and controls applied by research scientists generally in the preclinical or clinical study of new drugs; the descriptions or the results of such studies and tests contained in the Offering Memorandum are accurate and complete in all material respects, and the Company has no knowledge of any other studies or tests, the results of which reasonably call into question the results of such studies and tests described or referred to in the Offering Memorandum; and neither the

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Company nor any of its subsidiaries has received any notices or other correspondence from the FDA or any other governmental agency requiring the termination, suspension or modification of any animal studies or other preclinical tests, or clinical studies conducted by or on behalf of the Company or any of its subsidiaries or in which the Company or any of its subsidiaries has participated that are described in the Offering Memorandum or the results of which are referred to in the Offering Memorandum.

(u) Except as disclosed in the Offering Memorandum, there are no legal or governmental proceedings pending to which the Company or any of its subsidiaries is a party or of which any of their respective properties or assets is the subject which, if determined adversely to the Company or any subsidiary might have a Material Adverse Effect, or which might reasonably be expected to materially and adversely affect the consummation of the transactions contemplated by this Agreement or the performance by the Company of its obligations hereunder; to the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or, except as set forth or contemplated in the Offering Memorandum, threatened by others; and the aggregate of all pending legal or governmental proceedings to which the Company or any of its subsidiaries is a party or of which any of their respective properties or assets is the subject (other than the Company’s or any subsidiary’s patent applications currently pending before the U.S. Patent and Trademark Office or before any foreign governmental authority that administers the registration of patents), which are not described in the Offering Memorandum, including ordinary routine litigation incidental to the business, could not reasonably be expected to result in a Material Adverse Effect.

(v) No event has occurred nor has any circumstance arisen which, had the Notes been issued on such Delivery Date, would constitute a default or an Event of Default (as such term is defined in the Indenture).

(w) Neither the Company nor any of its subsidiaries is (i) in violation of its certificate of incorporation or bylaws, (ii) in default, and no event has occurred which, with notice or lapse of time or both, would constitute such a default, in the due performance or observance of any term, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which it or any of them may be bound or to which any of the properties or assets of the Company or any of its subsidiaries is subject or (iii) in violation of any law, ordinance, governmental rule, regulation or court decree to which any properties or assets of the Company or any of its subsidiaries may be subject or has failed to obtain any license, permit, certificate, franchise or other governmental authorization or permit necessary to the ownership of their properties or to the conduct of their business, except to the extent that any such default, event or violation described in the foregoing clauses (i), (ii) and (iii) would not have a Material Adverse Effect.

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(x) The Company is in compliance in all material respects with all presently applicable provisions of the Employee Retirement Income Security Act of 1974, as amended, including the regulations and published interpretations thereunder (“ERISA”); no “reportable event” (as defined in ERISA) has occurred with respect to any “pension plan” (as defined in ERISA) for which the Company would have any liability; the Company has not incurred and does not expect to incur liability under (i) Title IV of ERISA with respect to termination of, or withdrawal from, any “pension plan” or (ii) Sections 412 or 4971 of the Internal Revenue Code of 1986, as amended, including the regulations and published interpretations thereunder (the “Code”); and each “pension plan” for which the Company would have any liability that is intended to be qualified under Section 401(a) of the Code is so qualified in all material respects and nothing has occurred, whether by action or by failure to act, which would cause the loss of such qualification.

(y) The Company is subject to the reporting requirements of Section 13 or Section 15(d) of the Exchange Act. The Company has timely and, except with respect to the failure to provide information with respect to certain change of control and severance arrangements with respect to J. Milton Harris, which information was subsequently provided in an amendment to the Company’s Form 10-K for the year ended December 31, 2002 filed prior to the date of this Agreement, properly filed with the Commission all reports and other documents required to have been filed by it with the Commission pursuant to the Exchange Act and the Exchange Act Regulations (“Exchange Act Reports”).

(z) The Company and each of its subsidiaries, if applicable, have filed all federal, state and local income and franchise tax returns required to be filed through the date hereof or have requested extensions thereof and have paid all taxes due thereon, and no tax deficiency has been determined adversely to the Company which has had (nor does the Company or any of its subsidiaries have any knowledge of any tax deficiency which, if determined adversely to the Company or any of its subsidiaries, might have) a Material Adverse Effect.

(aa) There has been no storage, disposal, generation, manufacture, refinement, transportation, handling or treatment of toxic wastes, medical wastes, hazardous wastes or hazardous substances by the Company or any of its subsidiaries (or, to the knowledge of the Company, any predecessors in interest of the Company or any of its subsidiaries) at, upon or from any of the property now or previously owned or leased by the Company or any of its subsidiaries in violation of any applicable law, ordinance, rule, regulation, order, judgment, decree or permit or which would require remedial action under any applicable law, ordinance, rule, regulation, order, judgment, decree or permit, except for any violation or remedial action which would not have, or could not be reasonably likely to have, singularly or in the aggregate with all such violations and remedial actions, a Material Adverse Effect; there has been no material spill, discharge, leak, emission, injection, escape, dumping or release of any kind onto such property or into the environment surrounding such property of any toxic wastes,

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medical wastes, solid wastes, hazardous wastes or hazardous substances due to or caused by the Company or any of its subsidiaries or with respect to which the Company has knowledge, except for any such spill, discharge, leak, emission, injection, escape, dumping or release which would not have or would not be reasonably likely to have, singularly or in the aggregate with all such spills, discharges, leaks, emissions, injections, escapes, dumpings and releases, a Material Adverse Effect; and the terms “hazardous wastes,” “toxic wastes,” “hazardous substances” and “medical wastes” shall have the meanings specified in any applicable local, state, federal and foreign laws or regulations with respect to environmental protection.

(bb) There are no contracts or other documents which would be required to be described in the Offering Memorandum if the Offering Memorandum were a prospectus included in a registration statement on Form S-1 that have not been so described in the Offering Memorandum.

(cc) There is no relationship, direct or indirect, between or among the Company or any of its subsidiaries, on the one hand, and the directors, executive officers, shareholders, customers or suppliers of the Company or any of its subsidiaries, on the other hand, which would be required to be described in the Offering Memorandum if the Offering Memorandum were a prospectus included in a registration statement on Form S-1 that has not been so described.

(dd) Since the date as of which information is given in the Offering Memorandum through the date hereof, the Company has not (i) issued or granted any securities (other than Authorized Grants), (ii) incurred any material liability or obligation, direct or contingent, other than liabilities and obligations which were incurred in the ordinary course of business or referenced in Section 1(l)(iv) above, (iii) entered into any material transaction not in the ordinary course of business, other than as referenced in Section 1(l)(iv) above or (iv) declared or paid any dividend on its capital stock.

(ee) Except as disclosed in the Offering Memorandum, (i) there are no outstanding securities convertible into or exchangeable for, or warrants, rights or options issued by the Company to purchase, any shares of the capital stock of the Company (except, in the case of options, any Authorized Grants or Authorized Issuances), (ii) there are no statutory, contractual, preemptive or other rights to subscribe for or to purchase any Common Stock and (iii) there are no restrictions upon transfer of the Common Stock pursuant to the Company’s certificate of incorporation or bylaws.

(ff) Except as is limited by any material weakness in internal control over financial reporting disclosed in the Offering Memorandum, the Company (i) makes and keeps materially accurate books and records and (ii) maintains internal accounting controls which provide reasonable assurance that (A) transactions are executed in accordance with management’s authorization, (B) transactions are recorded as necessary to permit preparation of its financial

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statements and to maintain accountability for its assets, (C) access to its assets is permitted only in accordance with management’s authorization and (D) the reported accountability for its assets is compared with existing assets at reasonable intervals.

(gg) Neither the Company or any of its subsidiaries nor any director, officer, agent or employee acting on behalf of the Company or any of its subsidiaries has (i) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity, (ii) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds, (iii) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977 or (iv) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment.

(hh) No labor disturbance by the employees of the Company or any of its subsidiaries exists or, to the knowledge of the Company, is imminent which might be expected to have a Material Adverse Effect.

(ii) The Company is not, and upon the issuance and sale of the Notes as herein contemplated and the application of the net proceeds therefrom as described in the Offering Memorandum will not be, an “investment company” or an entity “controlled” by an “investment company” as such terms are defined in the Investment Company Act of 1940, as amended.

(jj) Assuming the accuracy of the representations and warranties of the Initial Purchasers contained in Section 6 and their compliance with the agreements set forth therein, the Securities will be eligible for resale pursuant to Rule 144A. No securities of the same class (within the meaning of Rule 144A(d)(3) under the Securities Act) as the Notes are listed on any national securities exchange registered under Section 6 of the Exchange Act or quoted on an automated inter-dealer quotation system.

(kk) None of the Company or any of its Affiliates (as defined in Rule 501(b) of Regulation D under the Securities Act (“Regulation D”)) (other than the Initial Purchasers, about which no representation is made by the Company), has, directly or through an agent, engaged or will engage in any form of general solicitation or general advertising in connection with the offering of the Notes (as those terms are used in Regulation D) under the Securities Act or in any manner involving a public offering within the meaning of Section 4(2) of the Securities Act; the Company has not entered into any contractual arrangement with respect to the distribution of the Notes except for this Agreement and the Company will not enter into any such arrangement.

(ll) None of the Company or any of its affiliates (other than the Initial Purchasers, about which no representation is made by the Company), has, directly or through any agent, sold, offered for sale, solicited offers to buy or otherwise negotiated in respect of, any “security” (as defined in the Securities Act) which is or will be integrated with the sale of the Notes in a manner that would require the registration under the Securities Act of the Notes.

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(mm) The Company has not taken, directly or indirectly, any action designed to cause or result in, or which has constituted or which might reasonably be expected to constitute, the stabilization or manipulation of the price of any security of the Company in connection with the offering of the Notes.

(nn) No consent, approval or vote of the Company’s shareholders is necessary or required in connection with the offering, issuance or sale of the Notes hereunder or, except as may be required under the Nasdaq National Market rules if the shares of Common Stock issuable upon conversion of the Notes exceed 20% of the outstanding voting stock of the Company, the issuance of shares of Common Stock upon conversion of the Notes.

(oo) Nektar Alabama is the Company’s only subsidiary that, for and as of the end of the most recent year as to which audited financial statements are included in the Offering Memorandum, had revenues or total assets that exceeded 10% of the Company’s consolidated revenues for such fiscal year or total assets as of the end of such fiscal year.

(pp) There is and has been no failure on the part of the Company or any of the Company’s directors or officers, in their capacities as such, to comply in all material respects with any provision of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith, including Section 402 related to loans and Sections 302 and 906 related to certifications.

2. Purchase, Sale and Delivery of Notes.

(a) Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company agrees to sell to each Initial Purchaser, and each Initial Purchaser agrees, severally and not jointly, to purchase from the Company, at a purchase price of 97.15% of the principal amount thereof (the “purchase price”) the principal amount of Firm Notes set forth opposite such Initial Purchaser’s name in Schedule 1 hereto (or such number increased as set forth in Section 8).

Delivery of and payment for the Firm Notes shall be made at the office of Sidley Austin Brown & Wood LLP, 555 California Street, San Francisco, California 94104, at 10:00 a.m. (New York City time) on September 28, 2005, or such later date as the Representatives shall designate, which date and time may be postponed by agreement between the Representatives and the Company or as provided in Section 8 (such date and time of delivery and payment for the Firm Notes being herein called the “First Delivery Date”). Delivery of the Firm Notes shall be made to the Initial Purchasers against payment of the purchase price by the Initial Purchasers. Payment for the Firm Notes shall be effected either by wire transfer of immediately available funds to an account with a bank in The City of New York, the account number and the ABA number for such bank

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to be provided by the Company to the Representatives at least two business days in advance of the First Delivery Date, or by such other manner of payment as may be agreed by the Company and the Representatives. It is understood that each Initial Purchaser has authorized the Representatives, for its account, to accept delivery of, issue a receipt for, and make payment of the purchase price for, the Firm Notes that it has agreed to purchase. The Representatives, individually and not as representatives of the Initial Purchasers, may (but shall not be obligated to) make payment of the purchase price for the Firm Notes to be purchased by any Initial Purchaser whose funds have not been received by the First Delivery Date but such payment shall not relieve such Initial Purchaser from its obligations hereunder.

(b) Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company hereby grants the Option to the Initial Purchasers to purchase, severally and not jointly, the Optional Notes at the same price as the Initial Purchasers shall pay for the Firm Notes and the principal amount of the Optional Notes to be sold to each Initial Purchaser shall be that principal amount which bears the same ratio to the aggregate principal amount of Optional Notes being purchased as the principal amount of Firm Notes set forth opposite the name of such Initial Purchaser in Schedule 1 hereto (or such number increased as set forth in Section 8). The Option may be exercised only to cover over-allotments in the sale of the Firm Notes by the Initial Purchasers. The Option may be exercised once in whole or in part at any time not more than 30 days subsequent to the date of this Agreement upon notice in writing or by facsimile by the Representatives to the Company setting forth the amount (which shall be an integral multiple of $1,000) of Optional Notes as to which the Initial Purchasers are exercising the Option.

The date for the delivery of and payment for the Optional Notes, being herein referred to as an “Optional Delivery Date,” which may be the First Delivery Date (the First Delivery Date and the Optional Delivery Date, if any, being sometimes referred to as a “Delivery Date”), shall be determined by the Representatives but shall not be later than five full business days after written notice of election to purchase Optional Notes is given. Delivery of the Optional Notes shall be made to the Initial Purchasers against payment of the purchase price by the Initial Purchasers. Payment for the Optional Notes shall be effected either by wire transfer of immediately available funds to an account with a bank in The City of New York, the account number and the ABA number for such bank to be provided by the Company to the Representatives at least two business days in advance of the Optional Delivery Date, or by such other manner of payment as may be agreed by the Company and the Representatives. It is understood that each Initial Purchaser has authorized the Representatives, for its account, to accept delivery of, issue a receipt for, and make payment of the purchase price for, the Optional Notes that it has agreed to purchase. Merrill Lynch, Pierce, Fenner & Smith Incorporated and Lehman Brothers Inc., individually and not as representatives of the Initial Purchasers, may (but shall not be obligated to) make payment of the purchase price for the Optional Notes to be purchased by any Initial Purchaser whose funds have not been received by the Delivery Date but such payment shall not relieve such Initial Purchaser from its obligations hereunder.

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(c) The Company will deliver against payment of the purchase price the Notes initially sold to qualified institutional buyers (“QIBs”), as defined in Rule 144A under the Securities Act (“Rule 144A”) in the form of one or more permanent global certificates (the “Global Notes”), registered in the name of Cede & Co., as nominee for The Depository Trust Company (“DTC”). Beneficial interests in the Notes initially sold to QIBs will be shown on, and transfers thereof will be effected only through, records maintained in book-entry form by DTC and its participants.

The Global Notes will be made available, at the request of the Representatives, for checking at least 24 hours prior to such Delivery Date. The Certificated Notes will be made available, at the request of the Initial Purchasers, for checking at least 48 hours prior to such Delivery Date.

(d) Time shall be of the essence, and delivery at the time and place specified pursuant to this Agreement is a further condition of the obligations of the Initial Purchasers hereunder.

3. Further Agreements of the Company. The Company further agrees with each Initial Purchaser as follows:

(a) The Company will advise the Initial Purchasers promptly of any proposal to amend or supplement the Offering Memorandum and not to effect any such amendment or supplement without the consent of the Representatives and/or Sidley Austin Brown & Wood LLP, counsel to the Initial Purchasers. Neither the consent of the Representatives, nor the Representatives’ delivery of any such amendment or supplement, shall constitute a waiver of any of the conditions set forth in Section 5. The Company will immediately notify the Representatives, and confirm such notice in writing, of (i) any filing made by the Company of information relating to the offering of the Notes by the Company with any securities exchange or any other regulatory body in the United States or any other jurisdiction, and (ii) prior to the completion of the placement of the Notes by the Initial Purchasers as evidenced by a notice in writing from the Representatives to the Company, any material changes in or affecting the condition, financial or otherwise, or the earnings, business affairs or business prospects of the Company which (x) make any statement in the Offering Memorandum false or misleading or (y) are not disclosed in the Offering Memorandum. In such event or if during such time any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Offering Memorandum in order that the Offering Memorandum will not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances existing at the time it is delivered to a purchaser, not misleading, to promptly notify the Representatives and/or Sidley Austin Brown & Wood LLP, counsel to the Initial Purchasers, and prepare, subject to the first sentence of this Section 3(a), such amendment or supplement as may be necessary to correct such untrue statement or omission.

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(b) The Company will furnish to the Initial Purchasers and to Sidley Austin Brown & Wood LLP, counsel to the Initial Purchasers, copies of the Preliminary Offering Memorandum and the Offering Memorandum (and all amendments and supplements thereto) in each case as soon as available and in such quantities as the Initial Purchasers reasonably request for internal use and for distribution to prospective purchasers; and to furnish to the Representatives on the date hereof two copies of the Offering Memorandum signed by duly authorized officers of the Company, one of which will include the independent auditors’ reports therein manually signed by such independent auditors. The Company will pay the expenses of printing and distributing to the Initial Purchasers all such documents.

(c) The Company will use its reasonable efforts to take such action as the Initial Purchasers may reasonably request from time to time, to qualify the Notes and the Conversion Shares for offering and sale under the securities laws of such jurisdictions as the Initial Purchasers may request and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions in the United States for as long as may be necessary to complete the resale of the Notes; provided that in connection therewith, the Company shall not be required to qualify as a foreign corporation or otherwise subject itself to taxation in any jurisdiction in which it is not otherwise so qualified or subject.

(d) The Company will apply the proceeds from the sale of the Notes as set forth under “Use of Proceeds” in the Offering Memorandum.

(e) During a period of 90 days from the date of the Offering Memorandum (the “Lockup Period”), the Company will not, and will cause its directors and executive officers not to, without the prior written consent of the Representatives, (i) directly or indirectly, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option right or warrant to purchase or lend or otherwise transfer or dispose of any Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock (collectively, the “Restricted Securities”) or (except as contemplated by the Registration Rights Agreement) file any registration statement under the Securities Act with respect to any Restricted Securities, or (ii) enter into any swap or any other agreement or any transaction (other than the Operative Documents) that transfers, in whole or in part, directly or indirectly, the economic consequence of ownership of any Restricted Securities, whether any such swap or transaction described in clause (i) or (ii) above is to be settled by delivery of Restricted Securities, in cash or otherwise. The restrictions of this Section 3(e) shall not apply to (u) the Notes offered by the Offering Memorandum, (v) the issuance of shares of Common Stock or options to purchase shares of Common Stock pursuant to the Company’s employee benefit plans in effect on the date of this Agreement, (w) the issuance of shares of Common Stock upon exercise or conversion of the Notes or any security outstanding on the date of this Agreement, (x) the issuance of shares of Common Stock or preferred stock in connection with private placements to strategic

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partners or as consideration for the Company’s acquisition of other companies or businesses, so long as the recipients of any such shares issued in such private placements deliver to the Representatives an agreement to the effect described in the preceding sentence prior to the issuance of such shares but without any of the exceptions described in this sentence, (y) the filing of one or more registration statements in order to register the shares of Common Stock or preferred stock issued pursuant to clause (x) above, or (z) the filing of one or more registration statements by the Company in order to register Restricted Stock for sale by the Company on a delayed or continuous basis pursuant to Rule 415 under the Securities Act, provided that no Restricted Stock registered pursuant to such registration statements is sold during the Lockup Period. The Company further agrees to cause each executive officer and director of the Company to furnish to the Representatives, prior to the First Delivery Date, a letter or letters, in form and substance satisfactory to counsel to the Initial Purchasers, pursuant to which each such person shall agree not to enter into any transaction described in clause (i) or (ii) of the first sentence of this paragraph; provided, however, that such restrictions shall not apply to (A) sales of Common Stock by the Company’s directors and executive officers pursuant to 10b5-1 plans covering the Company’s securities as in effect on the date of this Agreement (provided that such plans may be amended subsequent to the date of this Agreement to increase the number of shares of Common Stock that may be sold under such plans so long as the increase in the number of shares of Common Stock that may be sold under all such plans by all of such executive officers or directors of the Company does not exceed 500,000 shares of Common Stock in the aggregate), and (B) donations to charitable organizations consistent with past practices.

(f) The Company agrees that it will not, and will cause its Affiliates (as defined in Rule 501(b) of Regulation D) not to, directly or indirectly, solicit any offer to buy, sell or make any offer or sale of, or otherwise negotiate in respect of, securities of the Company of any class if, as a result of the doctrine of “integration” referred to in Rule 502 under the Securities Act, such offer or sale would render invalid (for the purpose of (i) the sale of the Notes by the Company to the Initial Purchasers, (ii) the resale of the Notes by the Initial Purchasers to subsequent purchasers or (iii) the resale of the Notes or Conversion Shares by such subsequent purchasers to others) the exemption from the registration requirements of the Securities Act provided by Section 4(2) thereof or by Rule 144A thereunder or otherwise. Notwithstanding the foregoing, no stockholder of the Company that does not control, is not controlled by or is not under common control with, an officer or director of the Company shall be deemed to be an Affiliate for purposes of this paragraph.

(g) For so long as any of the Notes are “restricted securities” within the meaning of Rule 144(a)(3) under the Securities Act, the Company will provide to any holder of the Notes or to any prospective purchaser of the Notes designated by any holder, upon request of such holder or prospective purchaser, information required to be provided by Rule 144A(d)(4) of the Securities Act if, at the time of such request, the Company is not subject to the reporting requirements under Section 13(a) or 15(d) of the Exchange Act.

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(h) Until the expiration of two years after the original issuance of the Notes, the Company will not, and will cause its Affiliates (as defined in Rule 501(b) of Regulation D) not to, resell any Notes or Conversion Shares which are “restricted securities” (as such term is defined under Rule 144(a)(3) under the Securities Act), whether as beneficial owner or otherwise (except as agent acting as a securities broker on behalf of and for the account of customers in the ordinary course of business in unsolicited broker’s transactions). Notwithstanding the foregoing, no stockholder of the Company that does not control, is not controlled by or is not under common control with, an officer or director of the Company shall be deemed to be an Affiliate for purposes of this paragraph.

(i) Each of the Notes will bear, to the extent applicable, the legend contained in “Notice to Investors” in the Offering Memorandum for the time period and upon the other terms stated therein, except after the Notes are resold pursuant to a registration statement effective under the Securities Act.

(j) The Company will take such steps as shall be necessary to ensure that it shall not become an “investment company” within the meaning of such term under the Investment Company Act, and the rules and regulations of the Commission thereunder.

(k) None of the Company or any of its affiliates will take, directly or indirectly, any action which is designed to stabilize or manipulate, or which constitutes or which might reasonably be expected to cause or result in stabilization or manipulation, of the price of any security of the Company in connection with the offering of the Notes.

(l) The Company will execute and deliver the Registration Rights Agreement in form and substance satisfactory to the Initial Purchasers.

(m) The Company will use its best efforts to assist the Initial Purchasers in arranging to cause the Notes to be accepted to trade in the PORTAL market (“PORTAL”) of the National Association of Securities Dealers, Inc. (“NASD”).

(n) The Company will use its best efforts to cause the Notes to be accepted for clearance and settlement through the facilities of DTC.

(o) The Company will use its best efforts to have the Conversion Shares approved by The Nasdaq National Market (“Nasdaq”) for inclusion prior to the effectiveness of the Registration Statement.

(p) The Company acknowledges and agrees that (i) the purchase and sale of the Notes pursuant to this Agreement is an arm’s-length commercial transaction between the Company, on the one hand, and the several Initial

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Purchasers, on the other hand, (ii) in connection with the offering contemplated hereby and the process leading to such transaction each Initial Purchaser is and has been acting solely as a principal and is not the agent or fiduciary of the Company, or its stockholders, creditors, employees or any other party, (iii) no Initial Purchaser has assumed or will assume an advisory or fiduciary responsibility in favor of the Company with respect to the offering contemplated hereby or the process leading thereto (irrespective of whether such Initial Purchaser has advised or is currently advising the Company on other matters) and no Initial Purchaser has any obligation to the Company with respect to the offering contemplated hereby except the obligations expressly set forth in this Agreement, (iv) the Initial Purchasers and their respective affiliates may be engaged in a broad range of transactions that involve interests that differ from those of the Company, and (v) the Initial Purchasers have not provided any legal, accounting, regulatory or tax advice with respect to the offering contemplated hereby and the Company has consulted its own legal, accounting, regulatory and tax advisors to the extent it deemed appropriate.

4. Expenses. The Company agrees to pay:

(a) the costs incident to the authorization, issuance, sale and delivery of the Notes, and any taxes payable in that connection;

(b) the costs incident to the preparation, printing and distribution of the Preliminary Offering Memorandum, the Offering Memorandum and any amendment or supplement to the Offering Memorandum, all as provided in this Agreement;

(c) the costs of producing and distributing the Operative Documents;

(d) the fees and expenses of Cooley Godward LLP and Ernst & Young LLP;

(e) the costs of distributing the terms of agreement relating to the organization of the underwriting syndicate and selling group to the members thereof by mail, telex or other means of communication;

(f) the fees and expenses of qualifying the Notes and the Conversion Shares under the securities laws of the several jurisdictions as provided in Section 3(c);

(g) all costs and expenses incident to (i) the preparation of the “road show” presentation materials and (ii) the road show traveling expenses of the Company;

(h) the costs of preparing the Notes;

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(i) all expenses and fees in connection with the application for inclusion of the Notes in the PORTAL market and the inclusion of the Conversion Shares on Nasdaq;

(j) the fees and expenses (including fees and disbursements of counsel) of the Trustee, and the costs and charges of any registrar, transfer agent, paying agent or conversion agent; and

(k) all other costs and expenses incident to the performance of the obligations of the Company under this Agreement;

provided that, except as provided in this Section 4 and in Section 7, the Initial Purchasers shall pay their own costs and expenses, including the costs and expenses of their counsel and any transfer taxes on the Notes which they may sell.

5. Conditions of the Initial Purchasers’ Obligations. The several obligations of the Initial Purchasers hereunder are subject to the accuracy, when made and on each Delivery Date, of the representations and warranties of the Company contained herein, to the performance by the Company of its obligations hereunder, and to each of the following additional terms and conditions:

(a) No Initial Purchaser shall have discovered and disclosed to the Company prior to or on such Delivery Date that the Offering Memorandum or any amendment or supplement thereto contains any untrue statement of a fact which, in the opinion of counsel to the Initial Purchasers, is material or omits to state any fact which is material and necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(b) All corporate proceedings and other legal matters incident to the authorization, form and validity of the Operative Documents and the Offering Memorandum or any amendment or supplement thereto, and all other legal matters relating to the Operative Documents and the transactions contemplated thereby shall be satisfactory in all material respects to counsel to the Initial Purchasers, and the Company shall have furnished to such counsel all documents and information that they may reasonably request to enable them to pass upon such matters.

(c) Cooley Godward LLP shall have furnished to the Initial Purchasers their written opinion, as counsel to the Company, addressed to the Initial Purchasers and dated such Delivery Date, in form and substance satisfactory to the Initial Purchasers, to the effect that:

(i) the Company has been duly incorporated and is a validly existing corporation in good standing under the laws of the State of Delaware;

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(ii) the Company has the requisite corporate power to own its property and assets and to conduct its business as described in the Offering Memorandum;

(iii) the Company is qualified as a foreign corporation to do business and is in good standing in the State of California;

(iv) the authorized, issued and outstanding capital stock of the Company was as set forth in the Offering Memorandum under the caption “Capitalization” as of the date stated therein.

(v) the Conversion Shares issuable on the date hereof have been duly authorized and reserved for issuance upon conversion of the Notes by all necessary corporate action and are free of preemptive rights arising under or pursuant to the Delaware General Corporation Law, the Company’s certificate of incorporation or bylaws; the Conversion Shares issuable on the date hereof, when so issued and delivered upon such conversion in accordance with the terms of the Indenture, will be duly authorized and validly issued, fully paid and nonassessable;

(vi) the statements in the Offering Memorandum under the captions “Description of the Notes” and “Description of Capital Stock,” insofar as they purport to summarize the provisions of the Indenture, the Registration Rights Agreement, the Notes, and the Common Stock (including the Conversion Shares) fairly present the material terms of such agreements in all material respects and include such information that would be called for with respect to such matters pursuant to the Act and the rules and the regulations thereunder in a Registration Statement on Form S-3 filed with the Commission;

(vii) there is no restriction upon the voting or transfer of any shares of Common Stock pursuant to the Company’s certificate of incorporation or bylaws;

(viii) to the knowledge of such counsel and other than as set forth in the Offering Memorandum, there is no action, proceeding or investigation pending or overtly threatened against the Company before any court or administrative agency that questions the validity of the Purchase Agreement or the Notes or that would materially and adversely affect the consummation of the transactions contemplated by the Purchase Agreement or the performance by the Company of its obligations thereunder or might result in a Material Adverse Effect (other than with respect to the Company’s or any of its subsidiaries’ patent applications currently pending before the U.S. Patent and Trademark Office or before any foreign governmental authority that administers the registration of patents, as to which we express no opinion);

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(ix) the execution and delivery of this Agreement, the Indenture and the Registration Rights Agreement and the issuance of the Notes and the Conversion Shares do not violate any provision of the certificate of incorporation or bylaws of the Company and, to the knowledge of such counsel, do not violate or contravene (a) any governmental statute, rule or regulation applicable to the Company or any of its subsidiaries; (b) any order, writ, judgment, injunction, decree or award which has been entered against the Company or any of its subsidiaries; or (c) the terms of any Material Contract (with or without the passage of time and/or notice);

(x) all consents, approvals, authorizations, or orders of, and filings, registrations, and qualifications with, any regulatory authority or governmental body in the United States required for the execution and delivery of the Purchase Agreement, the Indenture and the Registration Rights Agreement by the Company and the issuance of the Notes and the Conversion Shares have been made or obtained, except (a) as may be required under state securities or “Blue Sky” laws in connection with the distribution of the Notes and the Conversion Shares (as to which such counsel expresses no opinion), (b) as may be required by the rules and regulations of the NASD (as to which such counsel expresses no opinion), (c) as may be required under rules and regulations of the Nasdaq Stock Market (as to which such counsel expresses no opinion) and (d) any registration or qualification that may be required in connection with the Registration Rights Agreement;

(xi) no registration of the offering of the Notes or the Conversion Shares (assuming conversion on the date hereof pursuant to the terms of the Notes) under the Securities Act, and no qualification of the Indenture under the Trust Indenture Act, is required in connection with the purchase of the Notes by the Initial Purchasers or the initial resale of the Notes by the Initial Purchasers in the manner contemplated in the Purchase Agreement other than any registration or qualification that may be required in connection with the Registration Rights Agreement;

(xii) the statements in the Offering Memorandum under the caption “Certain United States Federal Income Tax Considerations,” insofar as they purport to constitute summaries of matters of United States federal income tax law and regulations or legal conclusions with respect thereto, constitute accurate summaries of the matters described therein in all material respects;

(xiii) the Company is not and will not become, as a result of the consummation of the transactions contemplated by the Purchase Agreement, and application of the net proceeds therefrom as described in the Offering Memorandum, required to register as an “investment company,” within the meaning of the Investment Company Act of 1940, as amended;

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(xiv) the Company has all necessary corporate right, power and authority to execute and deliver each of the Operative Documents to which it is a party and to perform its obligations thereunder and to issue, sell and deliver the Notes to the Initial Purchasers;

(xv) this Agreement has been duly authorized, executed and delivered by the Company;

(xvi) the Indenture has been duly authorized, executed and delivered by the Company and constitutes valid and binding obligations of the Company enforceable against the Company in accordance with its terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, by general principles of equity and limitations on availability of equitable relief, including specific performance (regardless of whether such enforceability is considered in a proceeding in equity or at law);

(xvii) the Registration Rights Agreement has been duly authorized, executed and delivered by the Company and constitutes valid and binding obligations of the Company enforceable against the Company in accordance with its terms, except as rights to indemnity contained therein may be limited by applicable law and except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, by general principles of equity and limitations on availability of equitable relief, including specific performance (regardless of whether such enforceability is considered in a proceeding in equity or at law); and

(xviii) the Notes have been duly authorized by the Company and when executed, issued and authenticated in accordance with terms of the Indenture and delivered to and paid for by the Initial Purchasers, will constitute legally valid and binding obligations of the Company, entitled to the benefits of the Indenture and enforceable against the Company in accordance with their terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, by general principles of equity and limitations on availability of equitable relief, including specific performance (regardless of whether such enforceability is considered in a proceeding in equity or at law).

In rendering such opinion, such counsel may state that its opinion is limited to matters governed by the federal laws of the United States of America, the laws of the State of California and the Delaware General Corporation Law, and with respect to the enforceability and binding effect of the Indenture, the Registration Rights Agreement and the Notes, solely the laws of the state of New York, and in respect of matters of fact,

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upon certificates of officers of the Company, provided that such counsel shall state that it believes that the Initial Purchasers and it are justified in relying upon such certificates. Such counsel shall also have furnished to the Initial Purchasers a written statement, addressed to the Initial Purchasers and dated such Delivery Date, in form and substance satisfactory to the Initial Purchasers, to the effect that during the course of preparing the Offering Memorandum, such counsel participated in conferences with officers and other representatives of the Company, the Company’s independent registered public accounting firm, the Initial Purchasers and their counsel, at which the contents of the Offering Memorandum were discussed, and while such counsel has not independently verified and is not passing upon or assuming responsibility for the accuracy, completeness or fairness of the statements made in the Offering Memorandum except as explicitly set forth above, nothing has come to the attention of such counsel that causes it to believe that the Offering Memorandum (other than the financial statements, financial and statistical data and supporting schedules as to which such counsel shall make no statement), as of its date or as of such Delivery Date, contained or contains any untrue statement of a material fact or omitted or omits to state a material fact necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading.

(d) Bradley Arant Rose & White LLP shall have furnished to the Initial Purchasers their written opinion, as special Alabama counsel to the Company, addressed to the Initial Purchasers and dated such Delivery Date, in form and substance satisfactory to the Initial Purchasers, to the effect that:

(i) Nektar Alabama has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Alabama and has all corporate power and authority necessary to own or hold its properties and conduct the businesses in which it is engaged, as described in the Offering Memorandum; except as otherwise disclosed in the Offering Memorandum, all of the issued and outstanding capital stock of Nektar Alabama has been duly authorized and validly issued, is fully paid and non-assessable and, based on the stock ledger of Nektar Alabama, is owned by the Company, directly or through subsidiaries; and to the knowledge of such counsel, none of the outstanding shares of capital stock of Nektar Alabama was issued in violation of the preemptive or similar rights of any securityholder of Nektar Alabama; and

(ii) the execution, delivery and performance of this Agreement, the Indenture and the Registration Rights Agreement and the issuance of the Notes and the Conversion Shares and the consummation of the transactions contemplated hereby and thereby by the Company do not result in any violation of the provisions of the articles of incorporation or bylaws of Nektar Alabama.

In rendering such opinion, such counsel may state that its opinion is limited to matters governed by the laws of the State of Alabama.

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(e) Sidley Austin Brown & Wood LLP, shall have furnished to the Initial Purchasers their written opinion, as counsel to the Initial Purchasers, addressed to the Initial Purchasers and dated such Delivery Date, in form and substance satisfactory to the Initial Purchasers.

(f) With respect to the letter of Ernst & Young LLP delivered to the Initial Purchasers concurrently with the execution of this Agreement (the “initial letter”), the Company shall have furnished to the Initial Purchasers a letter (the “bring-down letter”) of such accountants, addressed to the Initial Purchasers and dated such Delivery Date (i) confirming that they are independent accountants within the meaning of the Securities Act and are in compliance with the applicable requirements relating to the qualification of accountants under Rule 2-01 of Regulation S-X of the Commission, (ii) stating, as of the date of the bring-down letter (or, with respect to matters involving changes or developments since the respective dates as of which specified financial information is given in the Offering Memorandum, as of a date not more than five days prior to the date of the bring-down letter), the conclusions and findings of such firm with respect to the financial information and other matters covered by the initial letter and (iii) confirming in all material respects the conclusions and findings set forth in the initial letter.

(g) The Company shall have furnished to the Initial Purchasers on such Delivery Date a certificate, dated such Delivery Date and delivered on behalf of the Company by its chief executive officer and its chief financial officer, in form and substance satisfactory to the Initial Purchasers, to the effect that:

(i) the representations, warranties and agreements of the Company in Section 1 hereof are true and correct as of the date given and as of such Delivery Date; and the Company has complied in all material respects with all its agreements contained herein to be performed prior to or on such Delivery Date;

(ii) (A) neither the Company nor any of its subsidiaries has sustained, since the date of the latest audited financial statements included in the Offering Memorandum, any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, except (x) as set forth or contemplated in the Offering Memorandum and (y) for operating losses incurred in the ordinary course of business, or (B) since such date there has not been any change in the capital stock or long-term debt of the Company or any of its subsidiaries (except as disclosed in the Offering Memorandum and except for exercise of outstanding options described in the Offering Memorandum or pursuant to Authorized Grants and as provided in Section 1(l) above), or any change, or any development involving a prospective change, in or affecting the general affairs, management, financial position, stockholders’ equity or results of operations of the Company and its subsidiaries considered as one enterprise, except as set forth or contemplated in the Offering Memorandum; and

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(iii) Such officer has carefully examined the Offering Memorandum and, in such officer’s opinion (A) the Offering Memorandum, as of its date, did not include any untrue statement of a material fact and did not omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, and (B) since the date of the Offering Memorandum, no event has occurred which should have been set forth in a supplement or amendment to the Offering Memorandum.

(h) The Indenture shall have been duly executed and delivered by the Company and the Trustee and the Notes shall have been duly executed and delivered by the Company and duly authenticated by the Trustee.

(i) The Company and the Representatives shall have executed and delivered the Registration Rights Agreement (in form and substance satisfactory to the Initial Purchasers) and the Registration Rights Agreement shall be in full force and effect.

(j) The NASD shall have accepted the Notes for trading on PORTAL.

(k) (i) Neither the Company nor any of its subsidiaries shall have sustained, since the date of the latest audited financial statements included in the Offering Memorandum, any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, except (A) as set forth or contemplated in the Offering Memorandum and (B) for operating losses incurred in the ordinary course of business, and (ii) since such date there shall not have been any change in the capital stock or long-term debt of the Company or any of its subsidiaries (except as disclosed in the Offering Memorandum and except for exercise of outstanding options described in the Offering Memorandum or pursuant to Authorized Grants and as provided in Section 1(m) above), or any change, or any development involving a prospective change, in or affecting the general affairs, management, financial position, stockholders’ equity or results of operations of the Company and its subsidiaries considered as one enterprise, except as set forth or contemplated in the Offering Memorandum, the effect of which, in any such case described in clause (i) or (ii), is, in the reasonable judgment of the Initial Purchasers, so material and adverse as to make it impracticable or inadvisable to proceed with the sale or the delivery of the Notes being delivered on such Delivery Date on the terms and in the manner contemplated in the Offering Memorandum.

(l) The Company shall have furnished to the Initial Purchasers such further information, certificates and documents as the Initial Purchasers may reasonably request to evidence compliance with the conditions set forth in this Section 5.

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All opinions, letters, evidence and certificates mentioned above or elsewhere in this Agreement shall be deemed to be in compliance with the provisions hereof only if they are in form and substance satisfactory to counsel to the Initial Purchasers.

If any condition specified in this Section 5 shall not have been fulfilled when and as required to be fulfilled, this Agreement may be terminated by the Representatives by notice to the Company at any time at or prior to the First Delivery Date, and such termination shall be without liability of any party to any other party except as provided in Section 4 and except that Sections 1 and 7 shall survive any such termination and remain in full force and effect.

6. Representations, Warranties and Agreements of Initial Purchasers. Each Initial Purchaser, severally and not jointly, represents and warrants that such Initial Purchaser is a QIB. Each Initial Purchaser, severally and not jointly, agrees with the Company that:

(a) The Notes and the Conversion Shares have not been and will not be registered under the Securities Act in connection with the initial offering of the Notes.

(b) Such Initial Purchaser is a QIB;

(c) Such Initial Purchaser will not offer or sell the Notes in the United States by means of any form of general solicitation or general advertising within the meaning of Rule 502(c) of Regulation D, including (i) any advertisement, article, notice or other communication published in any newspaper, magazine or similar medium or broadcast over television or radio, or (ii) any seminar or meeting whose attendees have been invited by any general solicitation or general advertising in the United States; and

(d) Such Initial Purchaser has not offered or sold, and will not offer or sell, any Notes in the United States except to persons whom it reasonably believes to be QIBs.

7. Indemnification and Contribution.

(a) The Company shall indemnify and hold harmless each Initial Purchaser, its officers and employees and each person, if any, who controls any Initial Purchaser within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act from and against any loss, claim, damage or liability, joint or several, or any action in respect thereof (including, but not limited to, any loss, claim, damage, liability or action relating to purchases and sales of the Notes), to which that Initial Purchaser, officer, employee or controlling person may become subject:

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(i) insofar as such loss, claim, damage, liability or action arises out of, or is based upon: (A) any untrue statement or alleged untrue statement of a material fact contained in (1) any Preliminary Offering Memorandum or the Offering Memorandum, or in any amendment or supplement thereto, or (2) any blue sky application or other document prepared or executed by the Company (or based upon any written information furnished by the Company) filed in any jurisdiction specifically for the purpose of qualifying any or all of the Notes under the securities laws of any state or other jurisdiction (such application, document or information being hereinafter called a “Blue Sky Application”), or (B) the omission or alleged omission to state therein any material fact necessary to make the statements therein not misleading; or

(ii) to the extent of the aggregate amount paid in settlement of any litigation, or any investigation or proceeding by any governmental agency or body, commenced or threatened, or of any claim whatsoever based upon any such untrue statement or omission, or any such alleged untrue statement or omission; provided that (subject to Section 7(c)) any such settlement is effected with the written consent of the Company, which consent will not be unreasonably withheld,

and shall reimburse each Initial Purchaser and each such officer, employee and controlling person promptly upon demand for any and all expense whatsoever, as incurred (including the fees and disbursements of counsel chosen by the Representatives, except as reimbursement of such fees may be limited by Section 7(c)), reasonably incurred by that Initial Purchaser, officer, employee or controlling person in connection with investigating or defending or preparing to defend against any such loss, claim, damage, liability or action as such expenses are incurred; provided, however, that the Company shall not be liable in any such case to the extent that any such loss, claim, damage, liability or action arises out of, or is based upon, any untrue statement or alleged untrue statement or omission or alleged omission made in any Preliminary Offering Memorandum or the Offering Memorandum, or in any such amendment or supplement, or in any Blue Sky Application in reliance upon and in conformity with the written information furnished to the Company by or on behalf of any Initial Purchaser specifically for inclusion therein and described in Section 7(e); provided, further, that as to any Preliminary Offering Memorandum, this indemnity agreement shall not inure to the benefit of any Initial Purchaser, its officers or employees or any person controlling that Initial Purchaser on account of any loss, claim, damage, liability or action arising from the sale of Notes to any person by that Initial Purchaser if that Initial Purchaser failed to send or give a copy of the Offering Memorandum, as the same may be amended or supplemented, to that person, and the untrue statement or alleged untrue statement of a material fact or omission or alleged omission to state a material fact in such Preliminary Offering Memorandum was corrected in the Offering Memorandum, unless such failure resulted from non-compliance by the Company with Section 3(b). The foregoing indemnity agreement is in addition to any liability which the Company may otherwise have to any Initial Purchaser or to any officer, employee or controlling person of that Initial Purchaser.

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(b) Each Initial Purchaser, severally and not jointly, shall indemnify and hold harmless, the Company, its officers and directors, and each person, if any, who controls the Company within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act from and against any loss, claim, damage or liability, joint or several, or any action in respect thereof, to which the Company or any such director, officer or controlling person may become subject, insofar as such loss, claim, damage, liability or action arises out of, or is based upon:

(i) any untrue statement or alleged untrue statement of a material fact contained in any Preliminary Offering Memorandum or the Offering Memorandum or in any amendment or supplement thereto, or in any Blue Sky Application, or

(ii) the omission or alleged omission to state therein any material fact necessary to make the statements therein not misleading,

but in each case only to the extent that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with the written information furnished to the Company by or on behalf of that Initial Purchaser specifically for inclusion therein and described in Section 7(e), and shall reimburse the Company and any such director, officer or controlling person promptly upon demand for any legal or other expenses (except as reimbursement may be limited by Section 7(c)) reasonably incurred by the Company or any such director, officer or controlling person in connection with investigating or defending or preparing to defend against any such loss, claim, damage, liability or action as such expenses are incurred. The foregoing indemnity agreement is in addition to any liability which any Initial Purchaser may otherwise have to the Company or any such director, officer or controlling person.

(c) Promptly after receipt by an indemnified party under this Section 7 of notice of any claim or the commencement of any action, the indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under this Section 7, notify the indemnifying party in writing of the claim or the commencement of that action; provided, however, that the failure to notify the indemnifying party shall not relieve it from any liability which it may have under this Section 7 except to the extent it has been materially prejudiced by such failure and, provided, further, that the failure to notify the indemnifying party shall not relieve it from any liability which it may have to an indemnified party otherwise than under Section 7(a) and 7(b). If any such claim or action shall be brought against an indemnified party, and it shall notify the indemnifying party thereof, the indemnifying party shall be entitled to participate therein and, to the extent that it wishes, jointly with any other similarly notified indemnifying party, to assume the defense thereof with counsel satisfactory to the indemnified party. After notice from the indemnifying party to the indemnified party of its election to assume the defense of such claim or action, the indemnifying party shall not be liable to the indemnified party under this Section 7 for any legal or other expenses subsequently incurred by the indemnified party in connection with the defense thereof other than reasonable costs of investigation; provided, however, that the Initial Purchasers shall have the right to employ counsel to represent jointly the Initial Purchasers and their respective officers, employees and

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controlling persons who may be subject to liability arising out of any claim in respect of which indemnity may be sought by the Initial Purchasers against the Company under this Section 7, if the Initial Purchasers shall have reasonably concluded that there may be one or more legal defenses available to the Initial Purchasers and their respective officers, employees and controlling persons that are different from or additional to those available to the Company and its officers, employees and controlling persons, the fees and expenses of a single separate counsel, in addition to local counsel, shall be paid by the Company. No indemnifying party shall:

(i) without the prior written consent of the indemnified parties (which consent shall not be unreasonably withheld) settle or compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless such settlement, compromise or consent (1) includes an unconditional release of each indemnified party from all liability arising out of such claim, action, suit or proceeding and (2) does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of any indemnified party, or

(ii) be liable for any settlement of any such action effected without its written consent (which consent shall not be unreasonably withheld) but if settled with its written consent or if there be a final judgment of the plaintiff in any such action, the indemnifying party agrees to indemnify and hold harmless any indemnified party from and against any loss of liability by reason of such settlement or judgment.

(d) If the indemnification provided for in this Section 7 shall for any reason be unavailable or insufficient to hold harmless an indemnified party under Section 7(a) or 7(b) in respect of any loss, claim, damage or liability, or any action in respect thereof, referred to therein, each indemnifying party shall, in lieu of indemnifying such indemnified party, contribute to the amount paid or payable by such indemnified party as a result of such loss, claim, damage or liability, or action in respect thereof:

(i) in such proportion as shall be appropriate to reflect the relative benefits received by the Company on the one hand and the Initial Purchasers on the other from the offering of the Notes, or

(ii) if the allocation provided by clause 7(d)(i) is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause 7(d)(i) but also the relative fault of the Company on the one hand and the Initial Purchasers on the other with respect to the statements or omissions or alleged statements or alleged omissions that resulted in such loss, claim, damage or liability (or action in respect thereof), as well as any other relevant equitable considerations.

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The relative benefits received by the Company on the one hand and the Initial Purchasers on the other with respect to such offering shall be deemed to be in the same proportion as the total net proceeds from the offering of the Notes purchased under this Agreement (before deducting expenses) received by the Company on the one hand, and the total discounts and commissions received by the Initial Purchasers with respect to the Notes purchased under this Agreement, on the other hand, bear to the total gross proceeds from the offering of the Notes under this Agreement, in each case as set forth in the table under the caption “Plan of Distribution” in the Offering Memorandum.

The relative fault shall be determined by reference to whether the untrue or alleged untrue statement of a material fact or omission or alleged omission to state a material fact relates to information supplied by the Company or the Initial Purchasers, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such statement or omission.

The Company and the Initial Purchasers agree that it would not be just and equitable if the amount of contributions pursuant to this Section 7(d) were to be determined by pro rata allocation (even if the Initial Purchasers were treated as one entity for such purpose) or by any other method of allocation which does not take into account the equitable considerations referred to herein. The amount paid or payable by an indemnified party as a result of the loss, claim, damage or liability, or action in respect thereof, referred to above in this Section 7(d) shall be deemed to include, for purposes of this Section 7(d), any legal or other expenses reasonably incurred by such indemnified party in connection with investigating, preparing or defending any such litigation, investigation or proceeding by any governmental agency or body, or commenced or threatened action or claim.

Notwithstanding the provisions of this Section 7(d), no Initial Purchaser shall be required to contribute any amount in excess of the amount by which the total price at which the Notes resold by it in the initial placement of such Notes were offered to investors exceeds the amount of any damages which such Initial Purchaser has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission.

No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation.

For purposes of this Section 7(d), each person, if any, who controls an Initial Purchaser within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act shall have the same rights to contribution as such Initial Purchaser, and each person, if any, who controls the Company within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act shall have the same rights to contribution as the Company. The Initial Purchasers’ obligations to contribute as provided in this Section 7(d) are several in proportion to their respective purchase obligations and not joint.

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(e) The Initial Purchasers severally confirm that the statements (i) with respect to the offering of the Notes set forth in the third sentence of the ninth paragraph on the cover page of the Offering Memorandum; (ii) in the third and fifth paragraphs under the heading “Plan of Distribution”; (iii) in the paragraph under the heading “Plan of Distribution—Notes Are Not Being Registered” in the Offering Memorandum; (v) in the third and fourth sentences of the first paragraph under the heading “Plan of Distribution—New Issue of Notes” in the Offering Memorandum; and (vi) in the first and third sentences of the first paragraph under the heading “Plan of Distribution—Price Stabilization and Short Positions” in the Offering Memorandum are correct and constitute the only information furnished in writing to the Company by or on behalf of the Initial Purchasers specifically for inclusion in the Offering Memorandum.

8. Defaulting Initial Purchasers.

If, on any Delivery Date, any Initial Purchaser defaults in the performance of its obligations under this Agreement, the remaining non-defaulting Initial Purchasers shall be obligated to purchase the aggregate principal amount of Notes which the defaulting Initial Purchaser agreed but failed to purchase on such Delivery Date in the respective proportions which the total aggregate principal amount of Notes set opposite the name of each remaining non-defaulting Initial Purchaser in Schedule 1 hereto bears to the total aggregate principal amount of Notes set opposite the names of all the remaining non-defaulting Initial Purchasers in Schedule 1 hereto; provided, however, that the remaining non-defaulting Initial Purchasers shall not be obligated to purchase any Notes on such Delivery Date if the total aggregate principal amount of Notes which the defaulting Initial Purchasers agreed but failed to purchase on such date exceeds 9.09% of the total aggregate principal amount at maturity of Notes to be purchased on such Delivery Date, and any remaining non-defaulting Initial Purchaser shall not be obligated to purchase more than 110% of the aggregate principal amount at maturity of Notes which it agreed to purchase on such Delivery Date pursuant to the terms of Section 2. If the foregoing maximums are exceeded, the remaining non-defaulting Initial Purchasers, or those other purchasers satisfactory to the Initial Purchasers who so agree, shall have the right, but shall not be obligated, to purchase on such Delivery Date, in such proportion as may be agreed upon among them, the total aggregate principal amount of Notes to be purchased on such Delivery Date. If the remaining Initial Purchasers or other purchasers satisfactory to the Initial Purchasers do not elect to purchase on such Delivery Date the aggregate principal amount of Notes which the defaulting Initial Purchasers agreed but failed to purchase, this Agreement (or with respect to the Optional Delivery Date, the obligation of the Initial Purchasers to purchase the Optional Notes) shall terminate without liability on the part of any non-defaulting Initial Purchasers and the Company, except that the Company will continue to be liable for the payment of expenses to the extent set forth in Sections 4 and 10. As used in this Agreement, the term “Initial Purchaser” includes, for all purposes of this Agreement unless the context requires otherwise, any party not listed in Schedule 1 hereto who, pursuant to this Section 8, purchases Notes which a defaulting Initial Purchaser agreed but failed to purchase.

Nothing contained herein shall relieve a defaulting Initial Purchaser of any liability it may have to the Company for damages caused by its default. If other

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purchasers are obligated or agree to purchase the Notes of a defaulting or withdrawing Initial Purchaser, either the remaining non-defaulting Initial Purchasers or the Company may postpone the Delivery Date for up to seven full business days in order to effect any changes in the Offering Memorandum or in any other document or arrangement that, in the opinion of counsel to the Company or counsel to the Initial Purchasers, may be necessary.

9. Termination.

(a) The obligations of the Initial Purchasers hereunder may be terminated by the Initial Purchasers by notice given to and received by the Company prior to delivery of and payment for the Notes if, prior to that time: (i) there has occurred one of the events described in Section 5(k), or (ii) there has occurred any material adverse change in the financial markets in the United States, any outbreak of hostilities or escalation thereof or other calamity or crisis or any change or development involving a prospective change in national or international political, financial or economic conditions, in each case the effect of which is such as to make it, in the judgment of the Representatives, impracticable or inadvisable to market the Notes or to enforce contracts for the sale of the Notes, or (iii) trading in any securities of the Company has been suspended or materially limited by the Commission or The Nasdaq National Market, or if trading generally on the American Stock Exchange or the New York Stock Exchange or in The Nasdaq National Market has been suspended or materially limited, or minimum or maximum prices for trading have been fixed, or maximum ranges for prices have been required, by any of said exchanges or by such system or by order of the Commission, the National Association of Securities Dealers, Inc. or any other governmental authority, or a material disruption has occurred in commercial banking or securities settlement or clearance services in the United States or (iv) a banking moratorium has been declared by either Federal or New York authorities.

(b) If this Agreement is terminated pursuant to this Section 9, such termination shall be without liability of any party to any other party except as provided in Section 10 and provided, further, that Sections 1, 7 and 13 shall survive such termination and remain in full force and effect.

10. Reimbursement of Initial Purchasers’ Expenses. If (a) the Company shall fail to tender the Notes for delivery to the Initial Purchasers for any reason permitted under this Agreement or (b) the Initial Purchasers shall decline to purchase the Notes for any reason permitted under this Agreement (including the termination of this Agreement pursuant to Section 9), the Company shall reimburse the Initial Purchasers for the fees and expenses of their counsel and for such other out-of-pocket expenses as shall have been incurred by them in connection with this Agreement and the proposed purchase of the Notes, and upon demand the Company shall pay the full amount thereof to the Initial Purchasers. If this Agreement is terminated pursuant to Section 8 by reason of the default of one or more Initial Purchasers, the Company shall not be obligated to reimburse any defaulting Initial Purchaser on account of those expenses.

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11. Notices, etc. All statements, requests, notices and agreements hereunder shall be in writing, and:

(a) if to the Initial Purchasers, shall be delivered or sent by mail, telex or facsimile transmission to Merrill Lynch & Co., North Tower, World Financial Center, New York, New York 10281, Attention: Paul A. Pepe (Fax: 212-738-1069) and to Lehman Brothers Inc., 745 Seventh Avenue, New York, New York 10019, Attention: Syndicate Department (Fax: 646-834-8133) and 399 Park Avenue, 10^th Floor, New York, New York 10022, Attention: Director of Litigation, Official General Counsel (Fax: 212-520-0421); and

(b) if to the Company, shall be delivered or sent by mail, telex or facsimile transmission to Nektar Therapeutics, 150 Industrial Road, San Carlos, California 94070, Attention: Secretary (Fax: 650-620-5360).

provided, however, that any notice to an Initial Purchaser pursuant to Section 7(c) shall be delivered or sent by mail, telex or facsimile transmission to each such Initial Purchaser, which address will be supplied to any other party hereto by Merrill Lynch upon request. Any such statements, requests, notices or agreements shall take effect at the time of receipt thereof. The Company shall be entitled to act and rely upon any request, consent, notice or agreement given or made on behalf of the Initial Purchasers by Merrill Lynch.

12. Persons Entitled to Benefit of Agreement. This Agreement shall inure to the benefit of and be binding upon the Initial Purchasers, the Company and their respective successors. This Agreement and the terms and provisions hereof are for the sole benefit of only those persons, except that the representations, warranties, indemnities and agreements of the Company contained in this Agreement shall also be deemed to be for the benefit of the officers and employees of each Initial Purchaser and the person or persons, if any, who control each Initial Purchaser within the meaning of Section 15 of the Securities Act and any indemnity agreement of the Initial Purchasers contained in Section 7(b) of this Agreement shall be deemed to be for the benefit of directors, officers and employees of the Company, and any person controlling the Company within the meaning of Section 15 of the Securities Act. Nothing contained in this Agreement is intended or shall be construed to give any person, other than the persons referred to in this Section 12, any legal or equitable right, remedy or claim under or in respect of this Agreement or any provision contained herein.

13. Survival. The respective indemnities, representations, warranties and agreements of the Company and the Initial Purchasers contained in this Agreement or made by or on behalf of them, respectively, pursuant to this Agreement, shall survive the delivery of and payment for the Notes and shall remain in full force and effect, regardless of any termination or cancellation of this Agreement or any investigation made by or on behalf of any of them or any person controlling any of them.

14. Definition of the Terms “Business Day” and “Subsidiary.” For purposes of this Agreement, (a) ”business day” means any day on which the New York Stock Exchange, Inc. is open for trading and (b) ”subsidiary” has the meaning set forth in Rule 405 of the rules and regulations promulgated under the Securities Act.

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15. Governing Law. This Agreement shall be governed by, and construed in accordance with, the laws of the State of New York.

16. Counterparts. This Agreement may be executed in one or more counterparts and, if executed in more than one counterpart, the executed counterparts shall each be deemed to be an original but all such counterparts shall together constitute one and the same instrument.

17. Headings. The headings herein are inserted for convenience of reference only and are not intended to be part of, or to affect the meaning or interpretation of, this Agreement.

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If the foregoing correctly sets forth the agreement between the Company and the Initial Purchasers, please indicate your acceptance in the space provided for that purpose below.

Very truly yours,
NEKTAR THERAPEUTICS
By:	/s/ Ajit Gill
Name:	Ajit Gill
Title:	Chief Executive Officer

Accepted and agreed by:

MERRILL LYNCH, PIERCE, FENNER & SMITH

INCORPORATED

By:	/s/    Saira Ramasastry
	Authorized Representative

LEHMAN BROTHERS INC.

By:	/s/    David A. Galper
Name:	David A. Galper
Title:	Vice President

For themselves and as Representatives of the

other Initial Purchasers named in Schedule I hereto.

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SCHEDULE 1

Initial Purchasers	Principal Amount of Firm Notes
Merrill Lynch, Pierce, Fenner & Smith Incorporated	$	96,251,000
Lehman Brothers Inc.		96,251,000
Goldman, Sachs & Co.		26,675,000
Deutsche Bank Securities Inc.		20,075,000
WR Hambrecht + Co, LLC.		8,937,500
Leerink Swann & Company.		8,937,000
SG Cowen & Co., LLC.		8,937,000
SunTrust Capital Markets, Inc.		8,937,000
Total	$	275,000,000

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EX-99.1

Exhibit 99.1

Contact: Joyce Strand (650) 631-3138

Nektar Announces Exercise of Option to Purchase $40 million of Convertible Subordinated Notes

San Carlos, CA, September 27, 2005 — Nektar Therapeutics (NASDAQ:NKTR) today announced that initial purchasers have exercised their option to purchase an additional $40 million of Nektar’s 3.25% convertible subordinated notes due in 2012 pursuant to a purchase agreement dated September 22, 2005. This purchase increases the aggregate principal amount of 3.25% convertible subordinated notes to be sold in the offering to $315 million. The offering of the notes is being made to qualified institutional buyers under Rule 144A of the Securities Act of 1933, as amended. The offering is expected to close on September 28, 2005, subject to customary closing conditions.

The Notes will bear interest at a rate of 3.25% per annum and will be convertible into shares of Nektar common stock at an initial conversion rate of 46.4727 shares per $1,000 principal amount of Notes (subject to adjustment in certain circumstances), which is equivalent to an initial conversion price of approximately $21.52 per share. The Notes will be subordinated to all present and future senior debt of Nektar.

Nektar has reached agreements in principle with a limited number of holders of its outstanding convertible notes in privately negotiated transactions to repurchase approximately $71 million in principal amount of these outstanding obligations. Nektar may use additional net proceeds from the offering to repurchase additional outstanding convertible subordinated notes from a limited number of purchasers in privately negotiated transactions or unsolicited open market transactions. The remaining net proceeds of the offering will be used by Nektar for general corporate purposes, which may include investing in or furthering various product development programs, undertaking potential acquisitions, and developing technologies.

This announcement is neither an offer to sell nor a solicitation of an offer to buy any of these securities and shall not constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale is unlawful.

The securities will not be registered under the Securities Act of 1933, as amended, or any state securities laws. Unless so registered, the Notes and the common stock issuable upon conversion of the Notes may not be offered or sold in the United States except pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended, and applicable state laws.

This release contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 that reflect management’s current views as to Nektar Therapeutics’ business strategy, product and technology development plans and funding, and other future events and operations. These forward-looking statements involve uncertainties and other risks that are detailed in Nektar Therapeutics’ reports and other filings with the SEC, including its Annual Report on Form 10-K for the year ended December 31, 2004, as amended, and its Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2005. Actual results could differ materially from these forward-looking statements.

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