Exhibit 4.2 Dated as of March 3, 1999 Teachers Insurance and Annuity Association of America 730 Third Avenue New York, New York 10017 AmerUs Life Insurance Company c/o Amerus Capital Management 699 Walnut Street, Suite 1700 Des Moines, Iowa 50309-3945 Modern Woodmen of America 1701 First Avenue Rock Island, Illinois 61201 Ladies and Gentlemen: Reference is made to those certain Note Purchase Agreements between Hutchinson Technology Incorporated, a Minnesota corporation (the "Company"), and each of Teachers Insurance and Annuity Association of America, Central Life Assurance Company and Modern Woodmen of America (collectively, the "Purchasers"), each dated as of April 20, 1994 (as heretofore amended or otherwise modified, the "Agreements"), pursuant to which the Purchasers purchased the 7.46% Senior Notes of the Company in the aggregate original principal amount of $30,000,000 (the "Notes"). The addressees of this letter agreement (collectively, the "Noteholders") are the registered holders of 100% of the aggregate outstanding principal amount of the Notes as reflected in the Note Register required to be maintained by the Company pursuant to Section 10.1 of each of the Agreements, and the Noteholders whose signatures are affixed below hold 100% of the aggregate unpaid principal amount of the Notes outstanding as of the date hereof. The Company has informed the Noteholders that it desires to amend the Agreements in certain respects as of the date hereof, and the Noteholders have agreed to such amendments as more fully described below in this letter agreement ("this Amendment"). Now, therefore, the Company and the Noteholders (by their acceptance hereof) hereby agree as follows: 1. AMENDMENTS. The Agreements will be amended as hereafter in this paragraph 1 set forth, such amendments to become effective as provided in paragraph 3 hereof: (a) Section 3.1 of the Agreements shall be amended to be and read in its entirety as follows: "3.1. PREPAYMENTS AND PAYMENT AT MATURITY. On August 15, 1996 and on each February 15 and August 15 thereafter to and including August 15, 2003 (so long as any Notes shall remain outstanding), the Company will prepay, and there shall become due and payable, $1,875,000.00 in principal amount of the Notes (or such lesser principal amount of Notes as shall then be outstanding). Each such prepayment pursuant to this Section shall be at 100% of the principal amount so to be prepaid together with interest accrued thereon to the date of such prepayment, without premium. Upon the prepayment on any date of less than the entire outstanding principal amount of the Notes pursuant to SECTION 3.2 or SECTION 3.8, the principal amount of the Notes required to be prepaid on any February 15 or August 15 thereafter pursuant to this Section shall be reduced in the same proportion as the aggregate principal amount of the Notes outstanding immediately prior to said prepayment pursuant to SECTION 3.2 or SECTION 3.8 shall have been reduced by said prepayment. The Company will, in the event of any such reduction pursuant to the immediately preceding sentence, promptly after the prepayment of Notes giving rise to such reduction, furnish each holder of Notes with notice thereof setting forth the Company's calculation of the respective required prepayments and payment at final maturity due thereafter pursuant to this Section (giving effect to such reduction). On February 15, 2004, the Company will pay, and there shall become due and payable, the entire remaining unpaid principal amount of the Notes, together with interest accrued thereon. (b) Section 3.4 of the Agreements shall be amended to be and read in its entirety as follows: "3.4. ALLOCATION OF PARTIAL PREPAYMENTS. In the case of each prepayment, whether required or optional, of less than the entire unpaid principal amount of all outstanding Notes (other than any such prepayment pursuant to SECTION 3.8 in connection with the acceptance by one or more holders of Notes of a Prepayment Offer referred to in SECTION 3.8), the principal amount of the Notes so to be prepaid shall be allocated among all of the Notes at the time outstanding in proportion, as nearly as practicable, to the respective principal amounts thereof not theretofore prepaid." (c) Section 3.5 of the Agreements shall be amended to be and read in its entirety as follows: "3.5. MATURITY; SURRENDER, ETC. In the case of each prepayment of Notes, the principal amount of each Note to be prepaid shall become due and payable on the date fixed for such prepayment in this Agreement (if such prepayment is to be made pursuant to SECTION 3.1) or in the notice of such prepayment pursuant to SECTION 3.3 (if such prepayment is to be made pursuant to SECTION 3.2) or in the Trust Agreement referred to in SECTION 3.8 (if such prepayment is to made pursuant to SECTION 3.8), together with 2 interest accrued on such principal amount to such date and the Makewhole Amount, if any, payable in connection with such prepayment. Any Note paid or prepaid in full shall thereafter be surrendered to the Company upon its written request therefor and cancelled and not reissued." (d) Section 3 of the Agreements shall be further amended by adding thereto, following Section 3.7 thereof, a new Section 3.8, which new Section shall be and read in its entirety as follows: "3.8. PREPAYMENT OF NOTES PURSUANT TO TRUST AGREEMENT. The Company shall be required to prepay Notes of each holder thereof which shall have given notice of such holder's acceptance of a Prepayment Offer made by the Company pursuant to (and as the term `Prepayment Offer' is defined in) Section 7.2(b) of that certain Trust Agreement, dated as of March 3, 1999 (as from time to time supplemented and amended and in effect, the "TRUST AGREEMENT"), between the Company and U.S. Bank Trust National Association, a national banking association, as trustee thereunder (together with its successors as such trustee, the "TRUSTEE") for the equal and ratable benefit and security of the holders from time to time of the Notes and the holders from time to time of the Company's 1996 Notes referred to (and as the term `1996 Notes' is defined) in the Trust Agreement, each such prepayment to be made at the price and on the date determined in accordance with, and otherwise as provided in, said Section 7.2(b) of the Trust Agreement." 2. REPRESENTATIONS AND WARRANTIES. The Company represents and warrants and covenants to and for the benefit of the Noteholders as follows: (a) The execution and delivery by the Company of this Amendment and the performance by the Company of this Amendment and of the Agreements and the Notes as amended hereby (i) have been duly authorized by all requisite corporate action on the part of the Company (no action on the part of the shareholders of the Company being required therefor), (ii) do not require the consent or approval of (A) any Governmental Body, or (B) except as set forth below, any other Person, and (iii) do not and will not (A) violate (1) any provision of any law, statute, rule or regulation or of the articles of incorporation or by-laws of the Company, (2) any Order of any court, administrative body or arbitrator or any rule, regulation or Order of any Governmental Body binding upon the Company or any of its properties, or (3) any provision of any loan or credit agreement, indenture, mortgage or other agreement or instrument to which the Company is a party or by which it or any of its properties are or may be bound, or (B) result in any breach of or constitute (alone or with notice or lapse of time or both) a default under any such loan or credit agreement, indenture, mortgage or other agreement or instrument. (b) This Amendment, and the Agreements as amended hereby, constitute the legal, valid and binding obligations and agreements of the Company, enforceable against the Company in accordance with their respective terms, except as such enforcement may be limited by 3 applicable bankruptcy, insolvency, reorganization, moratorium or similar laws or equitable principles relating to or limiting creditors' rights generally. (c) As of the date hereof, and after giving effect to the amendments to the Agreements effected by this Amendment, no Default or Event of Default has occurred and is continuing under and within the meaning of the Agreements. 3. EFFECTIVENESS. The amendments to the Agreements provided for in this Amendment shall become effective upon the execution and delivery of counterparts of this Amendment by the Company and the holders of 100% in aggregate principal amount of Notes at the time outstanding (as provided in Section 12(a) of the Agreements). 4. MISCELLANEOUS. Except as specifically amended hereby, all terms and provisions of each of the Agreements shall remain in full force and effect. Without limiting the provisions of Section 15.1 of the Agreements, the Company will pay all expenses incurred by each Noteholder in connection with this Amendment. This Amendment may be executed in two or more counterparts, each of which shall be deemed an original, but all of which taken together shall constitute one and the same instrument. Capitalized terms used but not otherwise defined in this Amendment shall have the meanings assigned to them by each of the Agreements. 4 If you are in agreement with the foregoing, please so indicate by executing the form of acknowledgment set forth below, whereupon this Amendment shall become a binding agreement effective as of the date hereof. Very truly yours, HUTCHINSON TECHNOLOGY INCORPORATED By /s/ John A. Ingleman -------------------------------- Its CFO ----------------------------- Agreed to and accepted as of the date first above written. TEACHERS INSURANCE AND ANNUITY ASSOCIATION OF AMERICA By /s/ Diane Hom --------------------------------------------- Its Director-Private Placements ------------------------------------------ AMERUS LIFE INSURANCE COMPANY By /s/ Roger D. Fors --------------------------------------------- Its Vice President ------------------------------------------ MODERN WOODMEN OF AMERICA By /s/ Nick S. Coin --------------------------------------------- Its Manager, Securities Division -----------------------------------------