SC TO-T/A

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

AMENDMENT NO. 4 TO
SCHEDULE TO
(Rule 14d-100)

TENDER OFFER STATEMENT PURSUANT TO SECTION 14(d)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934

DADE BEHRING HOLDINGS, INC.

(Name of Subject Company (Issuer))

Belfast Merger Co.
a wholly-owned subsidiary of
Siemens Corporation
an indirect, wholly-owned subsidiary of
SIEMENS AKTIENGESELLSCHAFT
(Name of Filing Persons (Offeror))

Common Stock, $0.01 par value
(Title of Class of Securities)

23342J206
(CUSIP Number of class of securities)

Kevin M. Royer
Siemens Corporation
153 East 53rd Street
New York, New York 10022
(212) 258-4000
(Name, Address and Telephone No. of Person Authorized to Receive
Notices and Communications on Behalf of Filing Persons)

with a copy to:
John A. Healy
Clifford Chance US LLP
31 West 52nd Street
New York, New York 10019
(212) 878-8000

Calculation of Filing Fee

Transaction Valuation	Amount of Filing Fee*
$6,753,554,654	$207,348

* Previously paid.

o	Check the box if the filing relates solely to preliminary communications made before 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

AMENDMENT NO. 4 TO SCHEDULE TO

     This Amendment No. 4 amends and supplements the Tender Offer Statement on Schedule TO filed with the Securities and Exchange Commission on August 8, 2007 (the “Schedule TO”), relating to the offer by Belfast Merger Co., a Delaware corporation (“Purchaser”), which is a wholly-owned subsidiary of Siemens Corporation, a Delaware corporation (“Parent”), which is an indirect, wholly-owned subsidiary of Siemens Aktiengesellschaft, a corporation formed under the laws of the Federal Republic of Germany (“Siemens AG”), to purchase all of the outstanding shares of common stock, par value $0.01 per share (“Common Stock”), of Dade Behring Holdings, Inc., a Delaware corporation (the “Company”), together with the associated rights to purchase shares of Series A Junior Participating Preferred Stock (“Rights”) issued pursuant to the Rights Agreement, dated as of October 3, 2002, between the Company and Mellon Investor Services LLC, as Rights Agent (the Common Stock and the Rights together being referred to herein as the “Shares”), at a price of $77.00 per Share, net to the seller in cash, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated August 8, 2007 (the “Offer to Purchase”), and in the related Letter of Transmittal. Except as otherwise provided herein, this Amendment No. 4 does not modify any of the information previously reported on the Schedule TO.

     The Schedule TO is hereby supplemented and/or amended as provided below.

     Item 3. Identity and Background of Filing Person.

     Part 1 of Schedule A to the Offer to Purchase, “Directors and Officers of Siemens AG,” is amended and supplemented as follows:

1. The “Principal Occupation/Employment; Material Positions Held in Past Five Years” column with respect to Prof. Dr. Erich R. Reinhardt, a member of the Managing Board, is amended to read “Senior Vice-President; Group President of Medical Solutions Group of Siemens AG; member of the Supervisory Board of Dräger Medical AG since 2003; member of the Supervisory Board of Bio^M AG from 2001 to August 2007.”

2. The “Principal Occupation/Employment; Material Positions Held in Past Five Years” column with respect to John David Coombe, a member of the Supervisory Board, is amended to read “Chartered Accountant (FCA); Non Executive Director of HSBC Holdings plc since 2005; Non Executive Director of Home Retail Group plc since 2006; Chairman of Hogg Robinson Group plc since 2006; Non Executive Director of GUS plc from 2005 to 2006; Chief Financial Officer of GlaxoSmithKline plc from 2000 to 2005.”

3. The “Principal Occupation/Employment; Material Positions Held in Past Five Years” column with respect to Heinz Hawreliuk, a member of the Supervisory Board, is amended to read “Trade Union Secretary, IG Metall; member of the Supervisory Board of DaimlerChrysler Luft- und Raumfahrt Holding AG; member of the Supervisory Board of DaimlerChrysler Aerospace AG until 2006; member of the Supervisory Board of Eurocopter Deutschland GmbH.”

     Item 4. Terms of the Transaction.

     Section 1 of the Offer to Purchase, “Terms of the Offer; Expiration Date,” is hereby amended and supplemented by adding the following to the end of the first paragraph of Section 1 of the Offer to Purchase:

     “On September 27, 2007, Purchaser announced that it had extended the Expiration Date of the Offer to 12:00 Midnight, New York City time, on Wednesday, October 31, 2007. The Offer previously had

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been scheduled to expire at 12:00 Midnight, New York City time, on Wednesday, September 26, 2007. The Depositary has advised Purchaser that, as of 12:00 Midnight, New York City time, on September 26, 2007, an aggregate of 66,159,433 Shares had been validly tendered and not withdrawn from the Offer. In connection with this extension, the Company waived a requirement contained in the Merger Agreement that otherwise would have required that the extension be no longer than 15 Business Days.”

     The press release issued by Siemens AG announcing the extension of the Offer is attached hereto as Exhibit (a)(11).

     Item 12. Exhibits.

     Item 12 of the Schedule TO is hereby amended by adding the following exhibit:

     “(a)(11) Press release issued by Siemens AG, dated September 27, 2007.”

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SIGNATURE

     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.

Date: September 27, 2007	BELFAST MERGER CO.
	/s/ E. Robert Lupone
	Name:	E. Robert Lupone
	Title:	Authorized Representative
	/s/ Kenneth R. Meyers
	Name:	Kenneth R. Meyers
	Title:	Authorized Representative
	SIEMENS CORPORATION
	/s/ E. Robert Lupone
	Name:	E. Robert Lupone
	Title:	Senior Vice President, General Counsel and Secretary
	/s/ Kenneth R. Meyers
	Name:	Kenneth R. Meyers
	Title:	Vice President, Mergers and Acquisitions
	SIEMENS AKTIENGESELLSCHAFT
	/s/ E. Robert Lupone
	Name:	E. Robert Lupone
	Title:	Authorized Representative
	/s/ Kenneth R. Meyers
	Name:	Kenneth R. Meyers
	Title:	Authorized Representative

EXHIBIT INDEX

Exhibit No.

(a)(1)	Offer to Purchase, dated August 8, 2007.*
(a)(2)	Form of Letter of Transmittal.*
(a)(3)	Form of Notice of Guaranteed Delivery.*
(a)(4)	Form of Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9.*
(a)(5)	Form of Letter to brokers, dealers, commercial banks, trust companies and other nominees.*
(a)(6)	Form of Letter to be used by brokers, dealers, commercial banks, trust companies and other nominees for their clients.*
(a)(7)	Summary newspaper advertisement published in The Wall Street Journal on August 8, 2007.*
(a)(8)	Press Release issued by Siemens AG on July 25, 2007 (incorporated by reference to Exhibit 99.1 filed under cover of Schedule TO by Siemens AG with the Securities and Exchange Commission on July 25, 2007).*
(a)(9)	Press Release issued by Parent on September 5, 2007.*
(a)(10)	Press release issued by Parent, dated September 24, 2007, announcing the termination of the waiting period under the HSR Act.*
(a)(11)	Press release issued by Siemens AG, dated September 27, 2007.
(b)	None.
(d)(1)	Agreement and Plan of Merger, dated as of July 25, 2007, by and among Parent, Purchaser and the Company (incorporated by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by the Company with the Securities and Exchange Commission on July 26, 2007).*
(d)(2)	Confidentiality Agreement, dated May 22, 2007, between Siemens Medical Solutions USA, Inc. and the Company.*
(g)	None.
(h)	None.

* Previously filed.

EX-99.A.11

EXHIBIT (a)(11)

	Press Presse Prensa
	For the business and financial press   Munich, September 27, 2007

Siemens Extends Tender Offer for Acquisition of Dade Behring

Siemens has extended the expiration date for the cash tender offer for all outstanding shares of Dade Behring Holdings, Inc. (Nasdaq GS: DADE) to Wednesday, October 31, 2007, 12:00 midnight (EDT), as Siemens awaits merger control clearance by the European Commission.

The European Commission’s initial investigation period will expire on October 25, 2007, unless extended. U.S. antitrust clearance was already granted on September 17, 2007. Siemens expects to receive European merger control clearance and other regulatory approvals in time to close the transaction during calendar year 2007.

Joe Kaeser, Siemens CFO, stated: “We have made an attractive offer and do expect a smooth completion of the transaction after we have received full clearance from the antitrust authorities.”

As of midnight, New York City time, on Wednesday, September 26, 2007, an aggregate of 66,159,433 shares of common stock of Dade Behring had been validly tendered and not withdrawn, representing 82.55 percent of the outstanding common stock of Dade Behring.

While Siemens previously announced that it expected to close the transaction in the first calendar quarter of 2008, it now expects to close the transaction during the fourth quarter of calendar year 2007. Following completion of the tender offer, any remaining shares of Dade Behring will be acquired in a merger at the same price. The transaction has a value of approximately $7 billion. The tender offer is being made by a subsidiary

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Siemens AG
Corporate Communications
Media Relations
80312 Munich Reference number: XX 200709.68 e
Constantin Bimstiel
 
E-mail: constanti.birnstiel@siemens.com

of Siemens pursuant to an Agreement and Plan of Merger, dated as of July 25, 2007, by and among Siemens Corporation, its subsidiary, Belfast Merger Co., and Dade Behring.

Siemens (Berlin and Munich) is a global powerhouse in electrical engineering and electronics. The company has around 475,000 employees (incl. discontinued operations) working to develop and manufacture products, design and install complex systems and projects, and tailor a wide range of services for individual requirements. Siemens provides innovative technologies and comprehensive know-how to benefit customers in over 190 countries. Founded more than 160 years ago, the company focuses on the areas of Information and Communications, Automation and Control, Power, Transportation, Medical, and Lighting. In fiscal 2006 (ended September 30), Siemens had sales of €87.3 billion and net income of €3.033 billion, according to U.S. GAAP. Further information is available on the Internet at: www.siemens.com

About Dade Behring, Inc.

With 2006 revenue of more than US$1.7 billion, Dade Behring offers a wide range of products, systems and services designed to meet the day-to-day needs of clinical laboratories, delivering innovative solutions to customers and enhancing the quality of life for patients. Additional company information is available on the Internet at www.dadebehring.com.

This announcement is for informational purposes only and does not constitute an offer to purchase nor a solicitation of an offer to sell any securities. The Tender Offer Statement on Schedule TO, the Offer to Purchase and related materials filed by Siemens with the Securities and Exchange Commission (“SEC”) contain important information and should be read carefully before any decision is made with respect to the tender offer. These materials are available at no charge on the SEC’s web site (http://www.sec.gov) and requests for additional copies of such materials may be directed to Georgeson Inc., the Information Agent for the tender offer. The Information Agent can be reached at 17 State Street, 10th Floor, New York, New York 10004. Banks and brokers can call +1 (212) 440-9800 and all others can call toll free at (888) 605-7608.

This document contains forward-looking statements and information — that is, statements related to future, not past, events. These statements may be identified by words as “expects,” “looks forward to,” “anticipates,” “intends,” “plans,” “believes,” “seeks,” “estimates,” “will” or words of similar meaning. Such statements are based on our current expectations and certain assumptions, and are, therefore, subject to certain risks and uncertainties. A variety of factors, many of which are beyond Siemens' control, affect its operations, performance, business strategy and results and could cause the actual results, performance

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Siemens AG
Corporate Communications
Media Relations
80312 Munich Reference number: XX 200709.68 e
Constantin Bimstiel
 
E-mail: constanti.birnstiel@siemens.com

or achievements of Siemens worldwide to be materially different from any future results, performance or achievements that may be expressed or implied by such forward-looking statements. For us, particular uncertainties arise, among others, from: changes in general economic and business conditions (including margin developments in major business areas); the challenges of integrating major acquisitions and implementing joint ventures and other significant portfolio measures; changes in currency exchange rates and interest rates; introduction of competing products or technologies by other companies; lack of acceptance of new products or services by customers targeted by Siemens worldwide; changes in business strategy; the outcome of pending investigations and legal proceedings; our analysis of the potential impact of such matters on our financial statements; as well as various other factors. More detailed information about our risk factors is contained in Siemens’ filings with the SEC, which are available on the Siemens website, www.siemens.com, and on the SEC’s website, www.sec.gov. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in the relevant forward-looking statement as expected, anticipated, intended, planned, believed, sought, estimated or projected. Siemens does not intend or assume any obligation to update or revise these forward-looking statements in light of developments which differ from those anticipated.

3/3

Siemens AG
Corporate Communications
Media Relations
80312 Munich Reference number: XX 200709.68 e
Constantin Bimstiel
 
E-mail: constanti.birnstiel@siemens.com