SIXTH SUPPLEMENTAL INDENTURE TO INDENTURE DATED FEBRUARY 14, 2003

Exhibit 4.2

W. R. BERKLEY CORPORATION

TO

THE BANK OF NEW YORK MELLON, as Trustee

SIXTH SUPPLEMENTAL INDENTURE TO
INDENTURE DATED FEBRUARY 14, 2003
(SENIOR DEBT SECURITIES)

Dated as of September 14, 2009

7.375% Senior Notes due 2019

TABLE OF CONTENTS

W. R. BERKLEY CORPORATION

SIXTH SUPPLEMENTAL INDENTURE TO
INDENTURE DATED FEBRUARY 14, 2003
(SENIOR DEBT SECURITIES)

$300,000,000

7.375% Senior Notes due 2019

     SIXTH SUPPLEMENTAL INDENTURE, dated as of September 14, 2009, between W. R. BERKLEY CORPORATION, a Delaware corporation (the “Company”), and THE BANK OF NEW YORK MELLON, a banking corporation organized under the laws of the State of New York, as Trustee (the “Trustee”).

RECITALS

     The Company has heretofore executed and delivered to the Trustee an indenture for senior debt securities, dated as of February 14, 2003 (the “Indenture”), providing for the issuance from time to time of series of the Company’s Securities.

     Section 3.1 of the Indenture provides for various matters with respect to any series of Securities issued under the Indenture to be established in an indenture supplemental to the Indenture.

     Section 9.1(4) of the Indenture provides for the Company and the Trustee to enter into an indenture supplemental to the Indenture to establish the form or terms of Securities of any series as provided by Sections 2.1 and 3.1 of the Indenture.

     NOW, THEREFORE, THIS SIXTH SUPPLEMENTAL INDENTURE WITNESSETH:

     For and in consideration of the premises and the issuance of the series of Securities provided for herein, it is mutually agreed, for the equal and proportionate benefit of all Holders of the Securities of such series, as follows:

ARTICLE I

RELATION TO INDENTURE; DEFINITIONS

     Section 1.1. RELATION TO INDENTURE. This Sixth Supplemental Indenture constitutes an integral part of the Indenture.

     Section 1.2. DEFINITIONS. For all purposes of this Sixth Supplemental Indenture:

     (a) Capitalized terms used herein without definition shall have the meanings specified in the Indenture;

     (b) All references herein to Articles and Sections, unless otherwise specified, refer to the corresponding Articles and Sections of this Sixth Supplemental Indenture; and

     (c) The terms “herein,” “hereof,” “hereunder” and other words of similar import refer to this Sixth Supplemental Indenture.

     (d) “Fair Value,” when used with respect to Common Stock, means the fair value thereof as determined in good faith by the Board of Directors.

ARTICLE II

THE SERIES OF SECURITIES

     Section 2.1. TITLE OF THE SECURITIES. There shall be a series of Securities designated the “7.375% Senior Notes due 2019” (the “Notes”).

     Section 2.2. LIMITATION ON AGGREGATE PRINCIPAL AMOUNT. The aggregate principal amount of the Notes shall initially be limited to $300,000,000. The Company may, without the consent of the Holders of the Notes, issue additional Securities having the same interest rate, maturity date and other terms as described in the related prospectus supplement and prospectus. Any additional Securities, together with the Notes offered by the related prospectus supplement, will constitute a single series of Securities under the Indenture. No additional Securities may be issued if an Event of Default under the Indenture has occurred and is continuing with respect to the Securities.

     Section 2.3. PRINCIPAL PAYMENT DATE. The principal amount of the Notes outstanding (together with any accrued and unpaid interest) shall be payable in a single installment on September 15, 2019, which date shall be the Stated Maturity of the Notes Outstanding.

     Section 2.4. INTEREST AND INTEREST RATES. The rate of interest on each Note shall be 7.375% per annum, accruing from September 14, 2009, or from the most recent interest payment date (each such date, an “Interest Payment Date”) to which interest has been paid or duly provided for, payable semiannually in arrears on March 15 and September 15 of each year commencing March 15, 2010 until the principal thereof shall have become due and payable, and until the principal thereof is paid or duly provided for or made available for payment. The amount of interest payable on any Interest Payment Date shall be computed on the basis of a 360-day year of twelve 30-day months. The amount of interest payable for any partial period shall be computed on the basis of the actual number of days elapsed in a 360-day year of twelve 30-day months. In the event that any date on which interest is payable on any Note is not a Business Day, then payment of interest payable on such date will be made on the next succeeding day that is a Business Day (and without any interest or other payment in respect of any such delay). The interest installment so payable in respect of any Note, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in the Indenture, be paid to

the person in whose name such Note (or one or more Predecessor Securities) is registered at the close of business on March 1 or September 1 prior to such Interest Payment Date. Any such interest installment not punctually paid or duly provided for in respect of any Note shall forthwith cease to be payable to the registered Holder on such Regular Record Date and may either be paid to the Person in whose name such Note (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date to be fixed by the Company and the Trustee for the payment of such Defaulted Interest, notice whereof shall be given to the Holders of the Notes not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Notes may be listed, and upon such notice as may be required by such exchange, all as more fully provided in the Indenture.

     Section 2.5. PLACE OF PAYMENT. The Place of Payment where the Notes may be presented or surrendered for payment, where the Notes may be surrendered for registration of transfer or exchange and where notices and demand to or upon the Company in respect of the Notes and the Indenture may be served shall be the Corporate Trust Office of the Trustee.

     Section 2.6. REDEMPTION.

     (a) The Company may redeem the Notes at its option, in whole or in part, at any time and from time to time at a Redemption Price equal to the greater of (i) 100% of the principal amount of such Securities to be redeemed or (ii) an amount, as determined by an Independent Investment Banker, equal to the sum of the present values of the remaining scheduled payments of principal of and interest on the securities to be redeemed (not including any portion of such payments of interest accrued as of the date of redemption) discounted to the Redemption Date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Adjusted Treasury Rate, plus 50 basis points, plus, in either of the above cases, accrued and unpaid interest thereon to, but not including, the Redemption Date.

     (b) For the purposes of this Section 2.6,

     “Adjusted Treasury Rate” means, with respect to any Redemption Date:

extrapolated from such yields on a straight line basis, rounding to the nearest month; or

     The Adjusted Treasury Rate shall be calculated on the third Business Day preceding the Redemption Date.

     “Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the notes to be redeemed that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of such securities (“Remaining Life”).

     “Comparable Treasury Price” means (i) the average of three Reference Treasury Dealer Quotations for such Redemption Date, after excluding the highest and lowest Reference Treasury Dealer Quotations, or (ii) if the Independent Investment Banker obtains fewer than three such Reference Treasury Dealer Quotations, the average of all such quotations.

     “Independent Investment Banker” means one of the Reference Treasury Dealers appointed by us.

     “Reference Treasury Dealer” means:

     “Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date, the average, as determined by the Independent Investment Banker, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Independent Investment Banker at 5:00 p.m., New York City Time, on the third Business Day preceding such Redemption Date.

     The Company will mail a notice of redemption at least 30 days but not more than 60 days before the Redemption Date to each holder of the notes to be redeemed. If less than all

of the notes are to be redeemed, the trustee will select, by such method as it will deem fair and appropriate, including pro rata or by lot, the notes to be redeemed in whole or in part.

     Unless the Company defaults in payment of the Redemption Price, on and after the Redemption Date, interest will cease to accrue on the notes or portions thereof called for redemption.

     Section 2.7. DENOMINATION. The Notes shall be issuable only in registered form without coupons and in denominations of $1,000 and integral multiples thereof.

     Section 2.8. CURRENCY. Principal and interest on the Notes shall be payable in such coin or currency of the United States of America that at the time of payment is legal tender for payment of public and private debts.

     Section 2.9. FORM OF NOTES. The Notes shall be substantially in the form attached as EXHIBIT A hereto.

     Section 2.10. REGISTRAR AND PAYING AGENT FOR THE NOTES. The Trustee shall serve initially as Registrar and Paying Agent for the Notes.

     Section 2.11. SINKING FUND OBLIGATIONS. The Company has no obligation to redeem or purchase any Notes pursuant to any sinking fund or analogous requirement or upon the happening of a specified event or at the option of a Holder thereof.

     Section 2.12. DEFEASANCE AND COVENANT DEFEASANCE. The Company has elected to have both Section 4.2(2) of the Indenture (relating to defeasance) and Section 4.2(3) (relating to covenant defeasance) applied to the Notes.

     Section 2.13. PAYMENT OF TAXES. The Company will pay or discharge or cause to be paid or discharged, before the same shall become delinquent, all taxes, assessments and governmental charges levied or imposed upon the Company or any Subsidiary or upon the income, profits or property of the Company or any Subsidiary, and lawful claims for labor, materials and supplies, which, if unpaid, might by law become a lien upon the property of the Company or any Subsidiary; provided, however, that the Company shall not be required to pay or discharge or cause to be paid or discharged any such tax, assessment or governmental charge whose amount, applicability or validity is being contested in good faith by appropriate proceedings or where the failure to effect such payment is not adverse in any material respect to the Holders of the Notes.

     Section 2.14. LIMITATION ON LIENS ON STOCK OF PRINCIPAL SUBSIDIARIES. The Company will not, and it will not permit any Subsidiary of the Company to, at any time directly or in