SC TO-T/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1) of
the Securities Exchange Act of 1934

(Amendment No. 9)

DIONEX CORPORATION

(Name of Subject Company)

WESTON D MERGER CO.
THERMO FISHER SCIENTIFIC INC.

(Names of Filing Persons — Offeror)

Common Stock, Par Value $0.001 Per Share
(Title of Class of Securities)

254546104
(Cusip Number of Class of Securities)

Seth H. Hoogasian
Senior Vice President, General Counsel and Secretary
Thermo Fisher Scientific Inc.
81 Wyman Street
Waltham, Massachusetts 02451

(781) 622-1000
(Name, Address and Telephone Number of Person Authorized to Receive Notices
and Communications on Behalf of Filing Persons)

Copies to:
Matthew M. Guest, Esq.
Wachtell, Lipton, Rosen & Katz
51 West 52nd Street
New York, New York 10019
Telephone: (212) 403-1000

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$2,271,379,560	$161,949.36

*	Estimated for purposes of calculating the filing fee only. This amount is based on the offer to purchase all 19,167,760 outstanding shares of common stock of Dionex Corporation at a purchase price of $118.50 cash per share, as of November 30, 2010, the most recent practicable date.
**	The amount of the filing fee is calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, as amended, by multiplying the transaction valuation by 0.00007130.
þ	Check 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:	$	161,949.36.	Filing Party:	Thermo Fisher Scientific Inc. and Weston D Merger Co.
Form or Registration No.:	Schedule TO.		Date Filed:	December 20, 2010.

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:

þ     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

     This Amendment No. 9 (this “Amendment”) amends and supplements the Tender Offer Statement on Schedule TO (together with any amendments and supplements thereto, the “Schedule TO”) filed with the Securities and Exchange Commission (the “SEC”) on December 20, 2010, as amended on January 10, 2011, January 14, 2011, February 2, 2011, February 15, 2011, February 16, 2011, February 22, 2011, April 4, 2011 and April 12, 2011, and is filed by (i) Weston D Merger Co., a Delaware corporation (“Purchaser”) and an indirect wholly-owned subsidiary of Thermo Fisher Scientific Inc., a Delaware corporation (“Thermo Fisher”), and (ii) Thermo Fisher. The Schedule TO relates to the tender offer for all of the outstanding shares of common stock, par value $0.001 per share (the “Shares”), of Dionex Corporation, a Delaware corporation (“Dionex”), at a price of $118.50 per Share, net to the seller in cash, without interest, upon the terms and subject to the conditions set forth in the Offer to Purchase dated December 20, 2010 (the “Offer to Purchase”), and in the related Letter of Transmittal (the “Letter of Transmittal”), copies of which were filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively (which, together with any amendments or supplements thereto, collectively constitute the “Offer”).

     The information in the Offer to Purchase and the Letter of Transmittal is incorporated in this Amendment by reference to all of the applicable items in the Schedule TO, except that such information is amended and supplemented to the extent specifically provided in this Amendment No. 9. Capitalized terms used and not otherwise defined in this Amendment shall have the meanings assigned to such terms in the Offer to Purchase or in the Schedule TO.

Items 1 and 4.

Items 1 and 4 of the Schedule TO are hereby amended and supplemented as follows:

     “On May 10, 2011, Purchaser announced that it is confident in being able to secure all necessary outstanding regulatory and antitrust approvals or clearances in connection with the Offer. Subject to receipt of these approvals and assuming that all of the conditions described in Section 15—“Conditions of the Offer” have been satisfied, including the Minimum Condition, Purchaser expects to complete its acquisition of Dionex promptly following the Expiration Date, currently scheduled at 7:00 p.m., New York City time, on Friday, May 13, 2011. The press release issued by Thermo Fisher is attached hereto as Exhibit (a)(5)(L).”

Item 12.

Item 12 of the Schedule TO is hereby amended and supplemented as follows:

           “(a)(5)(L)           Press Release issued by Thermo Fisher Scientific Inc., dated May 10, 2011.”

SIGNATURES

     After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certify that the information set forth in this statement is true, complete and correct.

Weston D Merger Co.
By:	/s/ Seth Hoogasian
	Name:	Seth Hoogasian
	Title:	President
Thermo Fisher Scientific Inc.
By:	/s/ Seth Hoogasian
	Name:	Seth Hoogasian
	Title:	Senior Vice President, General Counsel and Secretary

Date: May 10, 2011

EXHIBIT INDEX

Exhibit No.	Description
(a)(1)(A)	Offer to Purchase dated December 20, 2010.*
(a)(1)(B)	Letter of Transmittal.*
(a)(1)(C)	Notice of Guaranteed Delivery.*
(a)(1)(D)	Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.*
(a)(1)(E)	Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.*
(a)(1)(F)	Summary Advertisement dated December 20, 2010.*
(a)(5)(A)	Joint Press Release issued by Thermo Fisher Scientific Inc. and Dionex Corporation on December 13, 2010 (incorporated by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Thermo Fisher Scientific Inc. on December 13, 2010).*
(a)(5)(B)	Investor Presentation, dated December 13, 2010 (incorporated by reference to Exhibit 99.2 to the Current Report on Form 8-K filed by Thermo Fisher Scientific Inc. on December 13, 2010).*
(a)(5)(C)	Transcript of Conference Call held December 13, 2010 (incorporated by reference to Exhibit 99.3 to the Current Report on Form 8-K filed by Thermo Fisher Scientific Inc. on December 13, 2010).*
(a)(5)(D)	Letter to Dionex employees from Marc Casper, Chief Executive Officer of Thermo Fisher, dated December 13, 2010 (incorporated by reference to the Schedule 14D-9 filed by Dionex Corporation on December 13, 2010).*
(a)(5)(E)	Press Release issued by Thermo Fisher Scientific Inc., dated January 10, 2011.*
(a)(5)(F)	Press Release issued by Thermo Fisher Scientific Inc., dated January 14, 2011.*
(a)(5)(G)	Excerpts from transcript of Conference Call held by Thermo Fisher Scientific Inc. on February 2, 2011 regarding Thermo Fisher Scientific Inc.’s fourth quarter and fiscal 2010 earnings release.*
(a)(5)(H)	Press Release issued by Thermo Fisher Scientific Inc., dated February 14, 2011.*
(a)(5)(I)	Press Release issued by Thermo Fisher Scientific Inc., dated February 14, 2011.*
(a)(5)(J)	Press Release issued by Thermo Fisher Scientific Inc., dated February 15, 2011.*
(a)(5)(K)	Press Release issued by Thermo Fisher Scientific Inc., dated April 4, 2011.*
(a)(5)(L)	Press Release issued by Thermo Fisher Scientific Inc., dated May 10, 2011.**
(b)	Commitment Letter dated as of December 12, 2010 among Thermo Fisher Scientific Inc., Barclays Bank PLC, JPMorgan Chase Bank, N.A. and J.P. Morgan Chase Manhattan Bank.*
(b)(1)	Indenture dated as of November 20, 2009 between Thermo Fisher Scientific Inc. and The Bank of New York Mellon Trust Company, N.A. (incorporated by reference to Exhibit 99.1 of the Form 8-K filed by Thermo Fisher Scientific Inc. on November 20, 2009 [File No. 1-8002]).*
(b)(2)	Third Supplemental Indenture dated as of February 22, 2011 between Thermo Fisher Scientific Inc. and The Bank of New York Mellon Trust Company, N.A. (incorporated by reference to Exhibit 99.2 of the Form 8-K filed by Thermo Fisher Scientific Inc. on February 22, 2011).*
(c)	Not applicable.
(d)	Agreement and Plan of Merger dated as of December 12, 2010 among Thermo Fisher Scientific Inc., Weston D Merger Co. and Dionex Corporation (incorporated by reference to the Form 8-K filed by Thermo Fisher Scientific Inc. on December 16, 2010).*

Exhibit No.	Description
(e)	Not applicable.
(f)	Not applicable.
(g)	Not applicable.
(h)	Not applicable.

*	Previously filed.
**	Filed herewith.

EX-99.A.5.L

Exhibit(a)(5)(L)

News

FOR IMMEDIATE RELEASE
Media Contact Information:	Investor Contact Information:
Ron O’Brien	Ken Apicerno
Phone: 781-622-1242	Phone: 781-622-1294
E-mail: ron.obrien@thermofisher.com	E-mail: ken.apicerno@thermofisher.com
Website: www.thermofisher.com

Thermo Fisher Scientific Provides Update on Acquisition of Dionex Corporation

Expects to Consummate Tender Offer Promptly Following Expiration on May 13, 2011,
Assuming Minimum Tender Condition is Satisfied

WALTHAM, Mass., May 10, 2011 — Thermo Fisher Scientific (NYSE: TMO), the world leader in serving science, is confident in being able to secure all necessary outstanding regulatory and antitrust approvals in connection with its previously announced tender offer to acquire all of the outstanding shares of Dionex Corporation (NASDAQ: DNEX) for $118.50 per share in cash.

Thermo Fisher expects to consummate the tender offer promptly after its expiration, scheduled for 7:00 p.m., New York City time, on Friday, May 13, 2011, subject to receipt of these approvals. Consummation of the tender offer also assumes that at least a majority of the outstanding shares of Dionex common stock, on a fully diluted basis, have been tendered and not withdrawn prior to the expiration of the offer and other standard closing conditions are satisfied.

About Thermo Fisher Scientific

Thermo Fisher Scientific Inc. (NYSE: TMO) is the world leader in serving science. Our mission is to enable our customers to make the world healthier, cleaner and safer. With revenues of nearly $11 billion, we have approximately 37,000 employees and serve customers within pharmaceutical and biotech companies, hospitals and clinical diagnostic labs, universities, research institutions and government agencies, as well as in environmental and process control industries. We create value for our key stakeholders through two premier brands, Thermo Scientific and Fisher Scientific, which offer a unique combination of continuous technology development and the most convenient purchasing options. Our products and services help accelerate the pace of scientific discovery, and solve analytical challenges ranging from complex research to routine testing to field applications. Visit www.thermofisher.com.

Forward Looking Statement

This press release contains forward-looking statements that involve a number of risks and uncertainties. Important factors that could cause actual results to differ materially from those indicated by such forward-looking statements are set forth in Thermo Fisher’s and Dionex’s respective quarterly and annual reports, under the caption “Risk Factors”, which are on file with the Securities and Exchange Commission (the “SEC”) and available on Thermo Fisher’s and Dionex’s respective websites. Additional important factors that could cause actual results to differ materially from those indicated by forward-looking statements include risks and uncertainties

relating to: competition and its effect on pricing, spending, third-party relationships and revenues; the need to develop new products and adapt to significant technological change; implementation of strategies for improving growth; general worldwide economic conditions including economic conditions in the areas in which Thermo Fisher and Dionex sell products, and related uncertainties; dependence on customers’ capital spending policies and government funding policies; the effect of exchange rate fluctuations on international operations; demand for analytical instrumentation; the effect of healthcare reform legislation; use and protection of intellectual property; the effect of changes in governmental regulations; and the effect of laws and regulations governing government contracts, as well as the possibility that expected benefits related to the transaction may not materialize as expected; the transaction not being timely completed, if completed at all; prior to the completion of the transaction, Dionex’s business experiencing disruptions due to transaction-related uncertainty or other factors making it more difficult to maintain relationships with employees, licensees, other business partners or governmental entities; and the parties being unable to successfully implement integration strategies. While Thermo Fisher and/or Dionex may elect to update forward-looking statements at some point in the future, Thermo Fisher and Dionex specifically disclaim any obligation to do so, even if estimates change and, therefore, you should not rely on these forward-looking statements as representing our views as of any date subsequent to today.

Additional Information

The description contained in this release is not an offer to buy or the solicitation of an offer to sell securities. The tender offer is being made pursuant to a tender offer statement on Schedule TO filed by Thermo Fisher with the SEC on December 20, 2010. Dionex filed a solicitation/recommendation statement on Schedule 14D-9 with respect to the tender offer on December 20, 2010. The tender offer statement (including an offer to purchase, a related letter of transmittal and other tender offer documents) and the solicitation/recommendation statement, in each case and any amendments thereto, contain important information that should be read carefully before making any decision to tender securities in the planned tender offer. Dionex stockholders may obtain a free copy of these materials (and all other tender offer documents filed with the SEC) on the SEC’s website: www.sec.gov. The Schedule TO (including the offer to purchase and related materials, and the Schedule 14D-9, including the solicitation/recommendation statement, as well as any amendments thereto, may also be obtained for free by contacting Innisfree M&A Incorporated, the information agent for the tender offer, at (877) 825-8964.

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