Exhibit 4(b) AMENDMENT NO. 2 TO REGISTRATION RIGHTS AGREEMENT ------------------------------------------------ AMENDMENT NO. 2 TO REGISTRATION RIGHTS AGREEMENT, dated as of July 1, 2003 (this "Amendment"), by and between TXU Corp., a Texas corporation (the "Company") and each of the entities listed on Schedule A attached hereto (each, a "Holder" and collectively, "Holders"). WHEREAS, the Company and UXT Holdings LLC and UXT Intermediary LLC (together, the "Initial Purchasers") have heretofore entered into a Registration Rights Agreement, dated as of November 22, 2002, (the "Agreement"; capitalized terms used herein without definition having the meaning ascribed thereto in the Agreement); WHEREAS, on December 19, 2002 the Company and the Initial Purchasers amended the Agreement pursuant to an Amendment No. 1 To Registration Rights Agreement; WHEREAS, on December 19, 2002, the Initial Purchasers, with the consent of the Company and TXU Energy, transferred an aggregate of $250 million of the Notes to the Holders other than the Initial Purchasers; WHEREAS, in connection with the above mentioned transfer the Initial Purchasers assigned all of their rights and obligations under the Agreement to such other Holders with respect to the transferred Notes; WHEREAS, the Holders hold in the aggregate all of the outstanding Notes; WHEREAS, pursuant to Section 2.04 of the Notes, on the date hereof the Holders will exchange (the "Exchange") their Notes for a preferred equity interest in the Company ("Class B Preferred Membership Interests") having substantially identical economic and other terms as the Notes and otherwise in form and substance satisfactory to the Holders; and WHEREAS, in contemplation of the Exchange, the Company and the Holders desire to further amend the Agreement. NOW, THERETOFORE, in consideration of the premises and the covenants hereinafter contained and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, and intending to be legally bound hereby, it is agreed as follows: 1. Effective Period. The definition of "Effective Period" ----------------- contained in Section 1 of the Agreement is amended in its entirety to read as follows: "Effective Period" shall mean the period commencing with the ----------------- effective date of the Shelf Registration Statement and ending on the date that is 180 days from the date that the number of Registrable Securities is less than ten percent (10%) of the initial amount of Registrable Securities; provided, however, that, for purposes of Section 12 hereof and Section 9 of the Exchange Agreement, "Effective Period" shall mean the period ending on the date that the Purchasers and their Affiliates, as a group, own Class B Preferred Membership Interests and Common Stock aggregating less than $75,000,000 in aggregate unpaid liquidation value (determined, in the case of Common Stock, on the basis of the Class B Preferred Membership Interest Exercise Price at the date Exchange Rights are exercised with respect to such Common Stock (as such terms are defined in the Exchange Agreement)). 2. "Registrable Securities" The definition of "Registrable ------------------------ Securities" shall be amended by replacing the term "Notes" with the term "Class B Preferred Membership Interests". 3. Added Definitions. The following definitions shall be added ----------------- in their entirety to Section 1 of the Agreement. "Class B Preferred Membership Interests" shall have the ---------------------------------------- meaning set forth in the LLC Agreement. "Exchange Agreement" means the Exchange Agreement, dated as of -------------------- November 22, 2002, among the Company, TXU Corp., UXT Intermediary LLC and UXT Holdings LLC, as amended by Amendment No. 1 to the Exchange Agreement, dated as of the date hereof, by and among the Company, TXU Corp. and the entities listed on Schedule A thereto, and as the same may be further amended from time to time in accordance with the terms thereof. "LLC Agreement" means the Company's Second Amended and --------------- Restated Limited Liability Company Agreement dated as of July 1, 2003, as the same may be amended from time to time in accordance with the terms thereof. 4. Amended Sections. (a) Sections 15(a), 15(e)(ii) and 15(e) ---------------- (iii) of the Agreement shall be amended by replacing in all instances the term "Notes" with the term "Class B Preferred Membership Interests". (b) Section 15(d)(i) of the Agreement shall be amended by replacing "Shearman & Sterling" with "Shearman & Sterling LLP". 5. Other Amendments. All references to the "Agreement" in the ---------------- Agreement shall, from and after the date hereof, be deemed to refer to the Agreement as amended by this Amendment. 6. Provisions of Agreement Not Otherwise Modified. Except as ---------------------------------------------- specifically amended by this Amendment, the Agreement is hereby ratified, approved and confirmed and remains in full force and effect. 2 IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of the date first above written. TXU CORP. By: ----------------------------------------- Name: Kirk R. Oliver Title: Treasurer UXT HOLDINGS LLC By: DLJ Merchant Banking III, Inc. as Managing Member By: ---------------------------------------- Name: Michael S. Isikow Title: Principal UXT INTERMEDIARY LLC By: UXT AIV, L.P., its Managing Member By: DLJ Merchant Banking III, Inc., as Managing General Partner By: -------------------------------------------- Name: Michael S. Isikow Title: Principal BENJAMIN MOORE PENSION By:-------------------------------------------- Name: Mark D. Millard Title: Authorized Signatory 3 THE BUFFALO NEWS OFFICE PENSION PLAN By:------------------------------------------ Name: Mark D. Millard Title: Authorized Signatory THE BUFFALO NEWS EDITORIAL PENSION PLAN By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory CORNHUSKER CASUALTY COMPANY By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory FLIGHTSAFETY INTERNATIONAL INC. RETIREMENT INCOME PLAN By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory FRUIT OF THE LOOM PENSION TRUST By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory 4 GEICO CORPORATION PENSION PLAN TRUST By:------------------------------------------- Name: Mark D. Millard Title: Authorized Signatory GOVERNMENT EMPLOYEES INSURANCE COMPANY By:------------------------------------------ Name: Mark D. Millard Title: Authorized Signatory JOHNS MANVILLE CORPORATION MASTER PENSION TRUST By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory JUSTIN BRANDS, INC. UNION PENSION PLAN AND JUSTIN BRANDS, INC. PENSION PLAN & TRUST By:---------------------------------------- Name: Mark D. Millard Title: Authorized Signatory ACME BRICK COMPANY PENSION TRUST By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory 5 SCOTT FETZER COMPANY COLLECTIVE INVESTMENT TRUST By:----------------------------------------- Name: Mark D. Millard Title: Authorized Signatory 6 Schedule A ---------- UXT Intermediary LLC UXT Holdings LLC Benjamin Moore Pension Buffalo News Office Pension Plan Buffalo News Editorial Pension Plan Cornhusker Casualty Company FlightSafety International Inc. Retirement Income Plan Fruit of the Loom Pension Trust GEICO Corporation Pension Plan Trust Government Employees Insurance Company Johns Manville Corporation Master Pension Trust Justin Brands, Inc. Union Pension Plan and Justin Brands, Inc. Pension Plan and Trust Acme Brick Company Pension Trust Scott Fetzer Company Collective Investment Trust 7