SC TO-T/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule TO/A

Amendment No. 4

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

Data Domain, Inc.

(Name of Subject Company (Issuer))

Envoy Merger Corporation

and

EMC Corporation

(Names of Filing Persons (Offerors))

COMMON STOCK, PAR VALUE $0.0001 PER SHARE

(Title of Class of Securities)

23767P109

(CUSIP Number of Class of Securities)

Paul T. Dacier, Esq.

EMC Corporation

176 South Street

Hopkinton, Massachusetts 01748

(508) 435-1000

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

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$ 2,011,050,090	$	112,216.60

* For purposes of calculating the filing fee pursuant to Rule 0-11(d) only, the Transaction Valuation was calculated on the basis of (i) the aggregate of 67,035,003 shares of common stock, par value $0.0001 per share, of Data Domain, Inc., consisting of: (a) 61,539,064 shares of common stock issued and outstanding and (b) 5,495,939 shares of common stock issuable on or before expiration of the offer upon the exercise of vested stock options, and (ii) the tender offer price of $30.00 per Share.

** The filing fee, calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, is calculated by multiplying the Transaction Valuation by .00005580.

þ 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: $ 112,216.60	Filing Party: Envoy Merger Corporation and EMC Corporation
Form or Registration No.: Schedule TO-T	Date Filed: June 2, 2009

¨ 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.

¨ issuer tender offer subject to Rule 13e-4.

¨ going-private transaction subject to Rule 13e-3.

¨ 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:  ¨

CUSIP Number:

23767P109

This Amendment No. 4 (“Amendment No. 4”) amends and supplements the Tender Offer Statement on Schedule TO originally filed on June 2, 2009, as amended on June 3, 2009, June 9, 2009 and June 15, 2009 (as amended, the “Schedule TO”), by EMC Corporation, a Massachusetts corporation (“EMC”), and Envoy Merger Corporation, a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of EMC, relating to the offer by Purchaser to purchase all outstanding shares of common stock, par value $0.0001 per share, of Data Domain, Inc., a Delaware corporation (“Data Domain”), at a price of $30.00 per Share, net to the seller in cash, without interest thereon and subject to reduction for any applicable withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated June 2, 2009 and annexed to and filed as Exhibit (a)(1)(i) to the Schedule TO (the “Offer to Purchase”), and in the related Letter of Transmittal.

The information set forth in the Offer to Purchase is incorporated by reference to all the items of this Amendment No. 4. All capitalized terms used in this Amendment No. 4 without definition have the meanings ascribed to them in the Offer to Purchase.

The item of the Schedule TO set forth below is hereby amended and supplemented as follows:

Item 12. Exhibits.

Item 12 of the Schedule TO is hereby amended and supplemented to add the following exhibit:

“(a)(1)(xiii) Text of press release issued by EMC dated June 17, 2009”

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.

Dated: June 17, 2009

EMC CORPORATION
By:	/s/ Paul T. Dacier
	Name: Paul T. Dacier Title: Executive Vice President and General Counsel

ENVOY MERGER CORPORATION
By:	/s/ Paul T. Dacier
	Name: Paul T. Dacier Title: President

EXHIBIT INDEX

(a)(1)(i)	Offer to Purchase dated June 2, 2009 *
(a)(1)(ii)	Form of Letter of Transmittal (including Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9) *
(a)(1)(iii)	Form of Notice of Guaranteed Delivery *
(a)(1)(iv)	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees *
(a)(1)(v)	Form of Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees *
(a)(1)(vi)	Form of summary advertisement dated June 2, 2009 *
(a)(1)(vii)	Text of press release issued by EMC dated June 1, 2009 (incorporated by reference to Exhibit 99.1 of the Current Report on Form 8-K filed by EMC with the Securities and Exchange Commission on June 1, 2009) *
(a)(1)(viii)	Slide Presentation dated June 1, 2009 (incorporated by reference to Exhibit 99.1 of the Schedule TO filed by EMC and Purchaser with the Securities and Exchange Commission on June 2, 2009) *
(a)(1)(ix)	Transcript of conference call held on June 1, 2009 *
(a)(1)(x)	Text of press release issued by EMC dated June 3, 2009 *
(a)(1)(xi)	Open letter to Data Domain employees, as published on June 9, 2009 *
(a)(1)(xii)	Text of press release issued by EMC dated June 15, 2009 *
(a)(1)(xiii)	Text of press release issued by EMC dated June 17, 2009
(b)	Not applicable
(c)	Not applicable
(d)(1)(i)	Form of Agreement and Plan of Merger by and among EMC, Purchaser and Data Domain (incorporated by reference to Exhibit 99.2 of the Current Report on Form 8-K filed by EMC with the Securities and Exchange Commission on June 1, 2009) *
(g)	Not applicable
(h)	Not applicable

* Previously filed

EX-99.(A)(1)(XIII)

Exhibit (a)(1)(xiii)

Contact:	Michael Gallant
	508-293-6357
	Gallant_Michael@emc.com

EMC TO RE-FILE HART-SCOTT-RODINO PREMERGER NOTIFICATION

HOPKINTON, Mass. – June 17, 2009 – EMC Corporation (NYSE: EMC) today announced that it will voluntarily re-file its notification under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 in connection with its all-cash offer to acquire all of the outstanding common stock of Data Domain, Inc. (NASDAQ: DDUP) for $30 per share in order to begin a new 15-day waiting period. Because EMC’s offer to acquire all of the outstanding common stock of Data Domain was cleared to the Federal Trade Commission (FTC) for review only this past Monday, June 15, the company will take this procedural step of re-filing its notification in the immediate term to ensure that the FTC has adequate time to review the transaction.

Paul T. Dacier, EMC’s Executive Vice President and General Counsel, said, “We continue to anticipate a routine review by the Federal Trade Commission of our offer to acquire Data Domain, and we believe we will receive regulatory approval in a timely manner. Our $30 per share all-cash offer to acquire Data Domain is not only superior, but it also delivers to Data Domain stockholders the price certainty and price protection its management team and board stated were important priorities when they negotiated the terms of their agreement with NetApp.”

About EMC

EMC Corporation (NYSE: EMC) is the world’s leading developer and provider of information infrastructure technology and solutions that enable organizations of all sizes to transform the way they compete and create value from their information. Information about EMC’s products and services can be found at www.EMC.com.

EMC is a registered trademark of EMC Corporation. All other trademarks used are the property of their respective owners.

# # #

Forward-Looking Statements

This release contains “forward-looking statements” as defined under the Federal Securities Laws. Actual results could differ materially from those projected in the forward-looking statements as a result of certain risk factors, including but not limited to: (i) adverse changes in general economic or market conditions; (ii) delays or reductions in information technology spending; (iii) our ability to protect our proprietary technology; (iv) risks associated with managing the growth of our business, including risks associated with acquisitions and investments and the challenges and costs of integration, restructuring and achieving anticipated synergies; (v) fluctuations in VMware, Inc.’s operating results and risks associated with trading of VMware stock; (vi) competitive factors, including but not limited to pricing pressures and new product introductions; (vii) the relative and varying rates of product price and component cost declines and the volume and mixture of product and services revenues; (viii) component and product quality and availability; (ix) the transition to new products, the uncertainty of customer acceptance of new product offerings and rapid technological and market change; (x) insufficient, excess or obsolete inventory; (xi) war or acts

of terrorism; (xii) the ability to attract and retain highly qualified employees; (xiii) fluctuating currency exchange rates; (xiv) litigation that we may be involved in; and (xv) other one-time events and other important factors disclosed previously and from time to time in EMC’s filings with the U.S. Securities and Exchange Commission. These statements are forward-looking, and actual results may differ materially. EMC disclaims any obligation to update any forward-looking statements in this release after the date of this release.

This release is neither an offer to purchase nor a solicitation of an offer to sell shares of Data Domain, Inc. EMC Corporation and Envoy Merger Corporation have filed with the SEC a tender offer statement on Schedule TO containing an offer to purchase, forms of letters of transmittal and other documents relating to the tender offer, and these documents have been mailed to the stockholders of Data Domain, Inc. These documents contain important information about the tender offer and stockholders of Data Domain, Inc. are urged to read them. Investors and stockholders of Data Domain, Inc. are able to obtain a free copy of these documents and other documents filed by EMC Corporation and Envoy Merger Corporation with the SEC at the website maintained by the SEC at www.sec.gov. In addition, the tender offer statement and related materials may be obtained for free by directing such requests to EMC Corporation at Attention: Office of the General Counsel, 176 South Street, Hopkinton, MA 01748.