SC TO-T/A

QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE TO
Amendment No. 1
TENDER OFFER STATEMENT UNDER SECTION 14(D)(1) OR 13(E)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934

IOMEGA CORPORATION
(Name of Subject Company (Issuer))

Emerge Merger Corporation
and
EMC Corporation
(Names of Filing Persons (Offerors))

Common Stock, par value $0.03-1/3 per share
(Title of Class of Securities)

462030305
(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 Numbers of Person Authorized
to Receive Notices and Communications on Behalf of Filing Persons)

Copy to:        
Alan B. Kalin, Esq.
Bingham McCutchen LLP
1900 University Avenue
East Palo Alto, California, 94303
(650) 849-4400

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$228,179,140	$8,968

*

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 59,267,309 shares of common stock, par value $0.03-1/3 per share, of Iomega Corporation outstanding on a fully diluted basis, consisting of: (a) 54,769,820 shares of common stock issued and outstanding, and (b) 4,497,489 shares of common stock subject to issuance upon the exercise of outstanding stock options, and (ii) the tender offer price of $3.85 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 0.00003930, and was previously paid in connection with the initial filing of the Schedule TO.

o 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: Not applicable
Form or Registration No.: Not applicable Filing Party: Not applicable
Date Filed: Not applicable

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:
ý	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. 1 (this "Amendment") amends and supplements the Tender Offer Statement on Schedule TO (as amended, the "Schedule TO") filed by Emerge Merger Corporation and EMC Corporation with the Securities and Exchange Commission on April 24, 2008. The Schedule TO relates to the offer by Emerge Merger Corporation, a Delaware corporation ("Purchaser") and a direct wholly owned subsidiary of EMC Corporation, a Massachusetts corporation ("EMC"), to purchase all outstanding shares of common stock, par value $0.03-1/3 per share (the "Shares"), of Iomega Corporation, a Delaware corporation ("Iomega"), at a price of $3.85 per Share, net to the seller in cash, without interest and less any required withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase dated April 24, 2008 (the "Offer to Purchase") and in the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the "Offer"), which were annexed to and previously filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively. The Schedule TO was filed on behalf of Purchaser and EMC.

        Except as specifically provided herein, this Amendment does not modify any of the information previously reported on the Schedule TO. All of the information set forth in the Offer to Purchase and the other exhibits to the Schedule TO are incorporated by reference herein in response to all the items of this Amendment. Capitalized terms used but not defined herein shall have the meanings assigned to such terms in the Offer to Purchase.

Item 12. Exhibits.

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

(a)(5)(a)
Text of press release issued by EMC and Iomega, dated April 25, 2008, announcing the commencement of the Offer

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.

EMC Corporation
By:	/s/  SUSAN I. PERMUT Name: Susan I. Permut Title: Senior Vice President and           Deputy General Counsel

Emerge Merger Corporation
By:	/s/  SUSAN I. PERMUT Name: Susan I. Permut Title: Secretary and Treasurer

Dated: April 25, 2008

EXHIBIT INDEX

(a)(1)(A)†	Offer to Purchase, dated April 24, 2008*
(a)(1)(B)†	Form of Letter of Transmittal (including Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9)*
(a)(1)(C)†	Form of Notice of Guaranteed Delivery*
(a)(1)(D)†	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees
(a)(1)(E)†	Form of Letter to Clients for Use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees
(a)(1)(F)†	Text of press release issued by EMC and Iomega, dated April 8, 2008 (incorporated by reference to Schedule TO filed by EMC and Purchaser with the Securities and Exchange Commission on April 8, 2008)
(a)(1)(G)†	Form of summary advertisement, published April 24, 2008
(a)(5)(a)	Text of press release issued by EMC and Iomega, dated April 25, 2008, announcing the commencement of the Offer
(b)	Not applicable
(d)(1)†	Agreement and Plan of Merger, dated as of April 8, 2008, by and among EMC, Purchaser and Iomega (incorporated by reference to Current Report on Form 8-K filed by the Company with the Securities and Exchange Commission on April 9, 2008)
(d)(2)†	Confidentiality Agreement, dated as of March 19, 2008, by and between EMC and Iomega
(d)(3)†	Form of Tender and Voting Agreement, dated as of April 8, 2008, by and between Purchaser and each of Jonathan Huberman, Stephen David, Reynolds Bish, Preston Romm, Thomas Kampfer, John Nolan, Daniel Maurer and Margaret Hardin
(d)(4)†	Letter Agreement, dated April 8, 2008, by and between EMC and Jonathan S. Huberman
(d)(5)†	Letter Agreement, dated April 8, 2008, by and between EMC and Thomas D. Kampfer
(d)(6)†	Form of Non-Competition Agreement, dated as of April 8, 2008, by and between EMC, Iomega and each of Jonathan S. Huberman and Thomas D. Kampfer
(g)	Not applicable
(h)	Not applicable

*

Documents mailed to Iomega stockholders.

†

Previously filed on the Schedule TO

QuickLinks

SIGNATURE
EXHIBIT INDEX

EX-99.(A)(5)(A)

QuickLinks -- Click here to rapidly navigate through this document

Exhibit (a)(5)(a)

Press Contacts

Dave Farmer
EMC Corporation
508-293-7206
farmer_dave@emc.com

Chris Romoser
Iomega
858-314-7148
romoser@iomega.com

EMC Commences its Tender Offer for all Outstanding Shares of Iomega

Early Termination of HSR Waiting Period Received

HOPKINTON, Mass. and SAN DIEGO, Calif.—April 25, 2008—EMC Corporation (NYSE: EMC), the world leader in information infrastructure solutions, and Iomega Corporation (NYSE: IOM), a global leader in data storage and protection for consumers and small businesses, today announced that EMC commenced a cash tender offer for all outstanding shares ("Shares") of the common stock of Iomega at a price of US$3.85 per share, net to the seller in cash. The cash tender is being made pursuant to the Offer to Purchase, dated April 24, 2008 and in connection with the Agreement and Plan of Merger, dated as of April 8, 2008, among EMC, Emerge Merger Corporation (a wholly owned subsidiary of EMC formed for the purpose of making the Offer) and Iomega, which EMC and Iomega publicly announced on April 8, 2008.

        The tender offer will expire at 12:00 midnight, Eastern Daylight Time, on Wednesday May 21, 2008, unless extended.

        There is no financing condition to the tender offer, but the tender offer is subject to certain other conditions set forth in the Offer to Purchase, including, obtaining regulatory approvals from antitrust authorities in the U.S. and the European Commission. On April 22, 2008, the Federal Trade Commission granted us early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, with respect to the tender offer and merger.

Additional Information and Where to Find It

        This press release is not an offer to purchase, a solicitation of an offer to purchase or a solicitation of an offer to sell any of the Shares. The solicitation and the offer to buy shares of Iomega common stock is being made pursuant to the Offer to Purchase and related materials that EMC and its wholly owned subsidiary filed with the U.S. Securities and Exchange Commission on April 24, 2008. EMC and its wholly owned subsidiary filed 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 Iomega filed a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. EMC, its wholly owned subsidiary and Iomega have commenced mailing these documents to the stockholders of Iomega. These documents contain important information about the tender offer and stockholders of Iomega are urged to read them carefully. Investors and stockholders of Iomega are able to obtain a free copy of these and other documents filed by Iomega or EMC 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 176 South Street, Attention: Office of the General Counsel, Hopkinton, MA 01748. Investors and stockholders may obtain a free copy of the solicitation/recommendation statement and such other documents from Iomega by directing requests to Iomega at 10955 Vista Sorrento Parkway, Attention: Corporate Secretary and General Counsel, San Diego, CA 92103.

For additional information, please contact the information agent for the offer.

The Information Agent for the Offer is:

470 West Avenue
Stamford, CT 06902
(203) 658-9400

Banks and Brokerage Firms Call: (800) 662-5200
Stockholders Call Toll Free: (800) 607-0088
E-mail: IOM.info@morrowco.com

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.

About Iomega

        Iomega Corporation, headquartered in San Diego, is a worldwide leader in innovative storage and network security solutions for small and mid-sized businesses, consumers and others. Iomega has sold more than 400 million digital storage drives and disks since its inception in 1980. To learn about all of Iomega's digital storage products and managed services solutions, please go to the Web at www.iomega.com. Resellers can visit Iomega at www.iomega.com/ipartner.

Press Contacts

Dave Farmer
EMC Corporation
508-293-7206
farmer_dave@emc.com

Chris Romoser
Iomega
858-314-7148
romoser@iomega.com

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

This release contains "forward-looking statements" as defined under the federal securities laws. These include, without limitation, all references to the date the Offer will be completed. 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) any adverse governmental reactions as we seek approvals for the acquisition of Iomega, or business partner reactions to the acquisition; (ii) material adverse changes in general economic or market conditions; (iii) the potential for Iomega's employees to leave their positions as a result of the acquisition; (iv) changes in the business of EMC or Iomega; or (v) other one-time events and other important factors disclosed previously and from time to time in EMC and Iomega's filings with the U.S. Securities and Exchange Commission. EMC disclaims any obligation to update any such forward-looking statements after the date of this release.

QuickLinks

Exhibit (a)(5)(a)