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. 10)

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. þ

TABLE OF CONTENTS

	Items 1 through 9 and 11
	Item 12
SIGNATURES
EXHIBIT INDEX
EX-99.A.5.M

     This Amendment No. 10 (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, April 12, 2011 and May 10, 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. 10. 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 through 9 and 11.

Items 1 through 9 and 11 of the Schedule TO are hereby amended and supplemented as follows:

     “At 7:00 p.m., New York City time, on Friday, May 13, 2011, the Offer expired as scheduled. According to the Depositary, as of the expiration of the Offer, (i) including Shares tendered by notice of guaranteed delivery, an aggregate of approximately 16,304,830 Shares were tendered and not withdrawn pursuant to the Offer, representing approximately 93% of the outstanding Shares, and (ii) excluding Shares tendered by notice of guaranteed delivery, an aggregate of approximately 13,988,751 Shares were tendered and not withdrawn pursuant to the Offer, representing approximately 80% of the outstanding Shares. Purchaser has accepted for payment all Shares validly tendered and not withdrawn prior to the expiration of the Offer. Payment for Shares accepted for payment is expected to be made promptly, in accordance with the terms of the Offer.

     Thermo Fisher intends to complete the acquisition of Dionex by means of a merger of Purchaser with and into Dionex, as a result of which Dionex will become a wholly owned subsidiary of Thermo Fisher. In the Merger, each outstanding Share (other than Shares held by Thermo Fisher, Purchaser, Dionex or any wholly owned subsidiary of Dionex, and any Shares held by stockholders who validly exercise their appraisal rights in connection with the Merger) will be cancelled and extinguished and automatically converted into the right to receive $118.50 per Share in cash, without interest. Thermo Fisher expects to complete the merger on an expedited basis pursuant to the short-form merger procedure available under Delaware law.

     The press release announcing the expiration of the Offer is attached hereto as exhibit (a)(5)(M) and is incorporated herein by reference.”

Item 12.

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

“(a)(5)(M) Press Release issued by Thermo Fisher Scientific Inc., dated May 16, 2011.”

SIGNATURES

     After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certifies 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 16, 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.*
(a)(5)(M)	Press Release issued by Thermo Fisher Scientific Inc., dated May 16, 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.

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

*	Previously filed.
**	Filed herewith.

EX-99.A.5.M

Exhibit (a)(5)(M)

News

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 Completes Tender Offer for Dionex Corporation

WALTHAM, Mass. (May 16, 2011) — Thermo Fisher Scientific (NYSE: TMO), the world leader in serving science, today announced that it has successfully completed its tender offer for Dionex Corporation (NASDAQ: DNEX), which expired at 7:00 pm, New York City time, on Friday, May 13, 2011.

“The acquisition of Dionex is consistent with our strategy of accelerating growth by increasing our depth of capabilities in innovative technologies and emerging markets,” said Marc N. Casper, president and chief executive officer of Thermo Fisher. “This combination creates a leading offering for our customers in chromatography instruments, software, consumables and services. With Dionex, we will expand our presence in attractive applied markets, including environmental analysis, water testing and food safety, and increase our commercial capabilities in China and other growing Asia-Pacific regions. We welcome Dionex employees to the Thermo Fisher team and look forward to working together to fulfill our mission, which is to enable our customers to make the world healthier, cleaner and safer.”

Based on preliminary information from the depositary for the tender, as of the expiration of the tender offer approximately 16,304,830 shares (including 2,316,079 shares that were tendered pursuant to guaranteed delivery procedures) were validly tendered and not withdrawn in the tender offer, representing approximately 93% of Dionex’s issued and outstanding shares. All validly tendered shares have been accepted for payment, which will be made in accordance with the terms of the tender offer.

Thermo Fisher intends to complete its acquisition of the remaining shares of Dionex through a short-form merger later this week. In the short-form merger, any remaining Dionex shares (other than those held by Thermo Fisher, Dionex or any wholly owned subsidiary of Dionex, and any shareholders who validly exercised their appraisal rights in connection with the merger) will be exchanged for $118.50 per share in cash.

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.

Safe Harbor Statement

The following constitutes a “Safe Harbor” statement under the Private Securities Litigation Reform Act of 1995: 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 the company’s Quarterly Report on Form 10-Q for the quarter ended April 2, 2011, under the caption “Risk Factors,” which is on file with the Securities and Exchange Commission and available in the “Investors” section of our Website under the heading “SEC Filings.” Important factors that could cause actual results to differ materially from those indicated by forward-looking statements include risks and uncertainties relating to: the need to develop new products and adapt to significant technological change; implementation of strategies for improving growth; general worldwide economic conditions and related uncertainties; dependence on customers’ capital spending policies and government funding policies; the effect of exchange rate fluctuations on international operations; 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 our anticipated acquisition of Dionex (the “transaction”) may not materialize as expected; the transaction not being timely completed, if completed at all; and 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. While we may elect to update forward-looking statements at some point in the future, we 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.

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