| SECURITIES AND EXCHANGE COMMISSION |
| WASHINGTON , DC 20549 |
| SCHEDULE TO-T/A |
| Tender Offer Statement Under Section 14(d)(1) or 13(e)(1) |
| of the Securities Exchange Act of 1934 |
| (Amendment No. 4) |
| Arch Chemicals, Inc. |
| (Name of Subject Company (Issuer)) |
| LG Acquisition Corp. |
| an indirect wholly owned subsidiary of |
| Lonza Group Ltd. |
| (Name of Filing Persons (Offerors)) |
| Common stock, par value $1.00 per share |
| (Title of Class of Securities) |
| 03937R102 |
| (CUSIP Number of Class of Securities) |
| Marc Funk, Esq. |
| Group General Counsel, Senior Vice President |
| Lonza Group Ltd. |
| Münchensteinerstrasse 38 |
| CH-4002 Basel, Switzerland |
| +41 61 316 81 11 |
| (Name, address and telephone number of person authorized to receive notices and communications on behalf of filing persons) |
Copies of all communications, including communications sent to agent for service, should be sent to:
| Scott Waldman, Esq. | Kevin T. Collins, Esq. | |
| Vice President and Secretary | Tobias L. Knapp, Esq. | |
| LG Acquisition Corp. | Jenner & Block LLP | |
| 90 Boroline Road | 919 Third Avenue | |
| Allendale, New Jersey 07401 | New York, New York 10022 | |
| (201) 316-9200 | (212) 891-1600 |
CALCULATION OF FILING FEE This Amendment No. 4 (this “Amendment No. 4”) amends and supplements the Tender Offer Statement on Schedule TO initially filed on July 15, 2011 as previously amended by (i) LG Acquisition Corp., a Virginia corporation (“Purchaser”) and an indirect wholly owned subsidiary of Lonza Group Ltd., a company organized under the laws of Switzerland (“Parent”), and (ii) Parent (the “Initial Schedule TO” and which, together with this Amendment No.4 and any additional amendments and supplements thereto, collectively constitute this “Schedule TO”). This Schedule TO relates to the offer by Purchaser to purchase all of the outstanding shares of common stock, par value $1.00 per share (the “Shares”), of Arch Chemicals, Inc., a Virginia corporation (the “Company”), at a price of $47.20 per Share, net to the holder thereof in cash, without interest thereon and less any required withholding of taxes, upon the terms and subject to the conditions set forth in the offer to purchase, dated July 15, 2011 (which, together with any amendments and supplements thereto, collectively constitute the “Offer to Purchase”), and in the related form of letter of transmittal (as it may be amended or supplemented, the “Letter ofTransmittal”). Copies of the Offer to Purchase and the Letter of Transmittal are attached to this Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively, and the Letter of Transmittal together with the Offer to Purchase constitute the “Offer”. Except as otherwise set forth below, the information set forth in the Initial Schedule TO remains unchanged and is incorporated herein by reference as relevant to items in this Amendment No. 4. Capitalized terms used but not otherwise defined herein have the meanings ascribed to such terms in the Initial Schedule TO and the related exhibits incorporated therein by reference. This Amendment No. 4 is being filed to amend and supplement Item 11 as reflected below. Item 11. Additional Information. The information set forth in the section of the Offer to Purchase entitled “Section 16—Certain Legal Matters; Regulatory Approvals” is hereby amended and supplemented by adding the following to the end of the sub-subsection “Certain Litigation”: “Parent and Purchaser have learned that GSS 5-08 Trust filed an amended complaint with respect to the matter captionedGSS 5-08 Trust v. Arch Chemicals, Inc. et al., and Parent and Purchaser have received a copy of the amended complaint dated August 2, 2011. The amended complaint names as defendants the Company, the members of the Company Board, Parent and Purchaser and alleges that the members of the Company Board breached their fiduciary duties to the Company’s shareholders in connection with the sale of the Company and that the Company, Parent and Purchaser aided and abetted the purported breaches of fiduciary duties. In support of the plaintiff’s claims, the amended complaint alleges that the proposed transaction between the Company and Purchaser undervalues the Company and involves an inadequate sale process and preclusive deal protection devices, and that the Company Board has made material misstatements of fact and has failed to disclose to shareholders all material information about the proposed transaction. The GSS 5-08 Trust suit seeks to enjoin the transaction, to obtain damages and to impose a constructive trust in favor of plaintiff and the class upon any property and profits received by defendants as a result of wrongful conduct. It also seeks attorneys’ and other fees and costs, in addition to seeking other relief.” SIGNATURES After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Transaction Valuation (1) Amount of Filing Fee (2) $1,244,271,815.20 $144,460 (1) Estimated for purposes of calculating the amount of the filing fee only, in accordance with Rule 0−11(d) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Calculated by multiplying $47.20, the per share tender offer price, by 26,361,691 shares of common stock of Arch Chemicals, Inc., which includes (a) 25,431,974 shares of common stock issued and outstanding; (b) 39,547 shares of common stock subject to outstanding options; (c) 323,778 shares of common stock subject to or deemed subject to outstanding performance unit awards; (d) 289,735 shares of common stock subject to or deemed subject to outstanding restricted stock unit awards; and (e) 276,657 shares of common stock subject to or deemed subject to outstanding phantom share awards. (2) The filing fee was calculated in accordance with Rule 0−11 of the Exchange Act and Fee Rate Advisory #5 for fiscal year 2011, issued December 22, 2010. Such fee equals 0.0001161 of the transaction value. x Check the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing. Amount Previously Paid: $144,460 Filing Party: LG Acquisition Corp. and Lonza Group Ltd. Form or Registration No.: Schedule TO-T Date Filed: July 15, 2011 o Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer. Check the appropriate boxes below to designate any transactions to which the statement relates: x third party tender offer subject to Rule 14d-1. o issuer tender offer subject to Rule 13e-4. o going-private transaction subject to Rule 13e-3. o amendment to Schedule 13D under Rule 13d-2. Check the following box if the filing is a final amendment reporting the results of the tender offer:o Date: August 4, 2011 LG Acquisition Corp. By: /s/ Joseph R. Colleluori Name: Joseph R. Colleluori Title: S.V.P. Corp. Development Lonza Group Ltd. By: /s/ Marc Funk Name: Marc Funk Title: Group General Counsel By: /s/ Joseph R. Colleluori Name: Joseph R. Colleluori Title: S.V.P. Corp. Development
