1 FILE PURSUANT TO RULE 424(b)(3) REGISTRATION STATEMENT NO. 333-52463 PROSPECTUS SUPPLEMENT NO. 12 TO PROSPECTUS DATED AUGUST 11, 1998 WESTERN DIGITAL CORPORATION ZERO COUPON CONVERTIBLE SUBORDINATED DEBENTURES DUE 2018 AND SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION THEREOF ------------------------- The following information supplements, and must be read in connection with, the information contained in the Prospectus, dated August 11, 1998 as supplemented by Prospectus Supplement No. 1 dated September 2, 1998, Prospectus Supplement No. 2 dated October 29, 1998, Prospectus Supplement No. 3 dated December 21, 1998, Prospectus Supplement No. 4 dated February 4, 1999, Prospectus Supplement No. 5 dated February 10, 1999, Prospectus Supplement No. 6 dated March 30, 1999, Prospectus Supplement No. 7 dated May 6, 1999, Prospectus Supplement No. 8 dated July 29, 1999, Prospectus Supplement No. 9 dated October 7, 1999, Prospectus Supplement No. 10 dated November 12, 1999 and Prospectus Supplement No. 11 dated November 17, 1999 (the "Prospectus"), of Western Digital Corporation, a Delaware corporation. This Prospectus Supplement must be delivered with a copy of the Prospectus. All capitalized terms not otherwise defined herein have the respective meanings ascribed to them in the Prospectus. The following information replaces in its entirety the information provided in the Prospectus under the caption "Selling Securityholders." ------------------------ SELLING SECURITYHOLDERS The following table sets forth information as of December 21, 1999, with respect to the Selling Securityholders, the respective principal amount of Debentures beneficially owned by each Selling Securityholder, the principal amount of Debentures offered hereby by each Selling Securityholder, the Common Stock owned by each Selling Securityholder and the Common Stock issued or issuable upon conversion of such Debentures, that may be sold from time to time pursuant to this Prospectus. The Debentures and the Common Stock issued or issuable upon conversion of such Debentures that may be offered pursuant to this Prospectus will be offered by the Selling Securityholders. PRINCIPAL AMOUNT OF DEBENTURES PERCENT OF TOTAL COMMON STOCK COMMON STOCK BENEFICIALLY OWNED OUTSTANDING OWNED PRIOR TO REGISTERED SELLING SECURITYHOLDERS AND OFFERED HEREBY DEBENTURES (1) CONVERSION HEREBY (2) - ----------------------- ------------------ ---------------- -------------- ------------ ABN AMRO Incorporated............... $ 10,700,000 * -- 159,804 Aim Charter Fund.................... 40,000,000 3 -- 597,400 Aim V.I. Growth and Income Fund 10,000,000 * -- 149,350 Aldebaran SAL....................... 60,000 * -- 896 Alta Partners Holdings, LDC......... 15,500,000 1 -- 231,492 Alutrade International SA........... 600,000 * -- 8,961 American Stores..................... 2,000,000 * -- 29,870 Argent Classic Convertible Arbitrage Fund (Bermuda) L.P.... 28,500,000 2 -- 425,647
2 Argent Classic Convertible $ 15,000,000 1 224,025 Arbitrage Fund L.P.............. -- Argent Offshore Fund L.P............ 7,600,000 * -- 113,506 Baltimore Gas & Electric............ 2,000,000 * -- 29,870 BancBoston Robertson Stephens....... 2,000,000 * -- 29,870 Bear Stearns Securities Corp........ 214,550,000 17 -- 3,204,304 Bell Atlantic Master Trust.......... 1,600,000 * -- 23,896 Black Diamond Ltd................... 5,491,000 * 47,170 82,008 Black Diamond Partners, L.P......... 5,249,000 * -- 78,393 Bonannay Investments Limited........ 100,000 * -- 1,493 Boston College Endowment Fund....... 542,000 * -- 8,094 BT Holdings......................... 11,000,000 * -- 164,285 Buffalo Balanced Fund, Inc.......... 2,000,000 * -- 29,870 Buffalo High Yield Fund, Inc........ 2,000,000 * -- 29,870 Business Investment Organisation Co. Ltd. -- metal a/c........... 280,000 * -- 4,181 Canadian Imperial Holdings Inc...... 22,500,000 2 -- 336,037 Carrigaholt Capital (Bermuda) L.P... 2,500,000 * -- 37,337 Century National Insurance Company.. 2,180,000 * -- 32,558 CFW-C, L.P.......................... 30,000,000 2 -- 448,050 Chapin Carpenter, Mary.............. 25,000 * -- 373 Charles Schwab Trust Company........ 240,000 * -- 3,584 Chrysler Insurance Company -- Total Return.................... 70,000 * -- 1,045 CIBC Oppenheimer Corp............... 19,000,000 1 -- 283,765 City of Richmond, Virginia.......... 225,000 * -- 3,360 City of Worcester, Massachusetts.... 400,000 * -- 5,974 Class IC Company, Ltd., The......... 2,500,000 * -- 37,337 Collins US Premier Equity Trust..... 250,000 * -- 3,733 Colonial Penn Life Insurance Co..... 500,000 * -- 7,467 Connell, Eileen M................... 40,000 * -- 597 Corbel Investments, Ltd............. 400,000 * -- 5,974 Corporate Investment Services SAL (Offshore) -- growth a/c.... 240,000 * -- 3,584 Cova Bond -- Debenture.............. 1,500,000 * -- 22,402 CPR (USA) Inc....................... 7,650,000 * -- 114,252 Credit Research & Trading LLC....... 500,000 * -- 7,467 Credit Suisse First Boston Corporation..................... 26,440,000 2 -- 394,881 Credit Suisse London Nominees Limited......................... 4,000,000 * 91,500 59,740 Data General........................ 300,000 * -- 4,480 D.E. Shaw Securities LP............. 400,000 * -- 5,974 Deeprock & Co....................... 5,000,000 * -- 74,675 Delaware Public Employee Retirement System............... 750,000 * -- 11,201 Delozier, Joseph and Jan............ 15,000 * -- 224 Detroit Edison Employees............ 2,250,000 * -- 33,603 Detroit Medical Endowment........... 850,000 * -- 12,694 Detroit Medical Pension............. 1,500,000 * -- 22,402 Deutsche Bank A.G................... 8,000,000 * -- 119,480 2
3 Donaldson, Lufkin & Jenrette $ 561,000 * 8,378 Securities Corporation.......... -- Double Black Diamond Offshore LDC... 2,316,000 * 9,300 34,589 Dunn Family Trust dated 10/28/88, David J. Dunn Trustee........... 5,000,000 * 100,000 74,675 Employers' Reinsurance Corporation.. 4,795,000 * -- 71,613 Ensign Peak Advisors................ 3,000,000 * -- 44,805 EQ Putnam Balanced Portfolio........ 50,000 * -- 746 Federated Equity Income Fund, Inc... 29,000,000 2 -- 433,115 Federated Insurance Series, a Massachusetts business trust, on behalf of its Federated Equity Income Fund II........... 600,000 * -- 8,961 Forest Alternative Strategies Fund A-5........................ 15,000,000 1 -- 224,025 Forest Alternative Strategies Fund A-5I....................... 1,080,000 * -- 16,129 Forest Alternative Strategies Fund A-5M....................... 510,000 * -- 7,616 Forest Alternative Strategies Fund B-3........................ 700,000 * -- 10,454 Forest Global Convertible Fund A-1.. 90,000 * -- 1,344 Forest Global Convertible Fund A-5.. 23,510,000 2 -- 351,121 Forest Global Convertible Fund B-1.. 400,000 * -- 5,974 Forest Global Convertible Fund B-2.. 500,000 * -- 7,467 Forest Global Convertible Fund B-3.. 400,000 * -- 5,974 Forest Global Convertible Fund B-5.. 800,000 * -- 11,948 Forest Greyhound c/o Forest Investment Management LLC....... 400,000 * -- 5,974 Forest Performance Fund............. 800,000 * -- 11,948 Fort Dearborn Life Insurance Company......................... 360,000 * -- 5,376 Fox Family Foundation DTD 10/10/87 c/o Forest Investment Management LLC.................. 100,000 * -- 1,493 Fox Family Portfolio Partnership c/o Forest Investment Management LLC.................. 900,000 * -- 13,441 Franklin Investors Securities Trust -- Convertible Securities Fund............................ 6,000,000 * -- 89,610 Franklin Strategic Series -- Franklin Small Cap Growth Fund............................ 23,800,000 2 -- 355,453 Franklin U.S. Small Cap Growth 200,000 * -- 2,987 Fund............................ Fundamental Investors, Inc.......... 22,500,000 2 -- 336,037 Gencorp............................. 4,350,000 * -- 64,967 3
4 General Motors Domestic Group Pension Trust................... $ 2,500,000 * -- 37,337 George Putnam Fund of Boston, The... 8,810,000 * -- 131,577 Gleneagles Fund Company, The........ 1,500,000 * -- 22,402 GLG Global Convertible Fund PLC..... 10,000,000 * -- 149,350 Goldman, Sachs & Co................. 6,900,000 * (3) 103,051 Goldman Sachs International......... 17,000,000 1 -- 253,895 GPZ Trading LLC..................... 8,000,000 * -- 119,480 Gruber-McBaine International........ 200,000 * -- 2,987 Habile Investments Limited.......... 200,000 * -- 2,987 Halliburton High Yield.............. 1,250,000 * -- 18,668 Hamilton Global Investors Limited 6,000,000 * -- 89,610 Hamilton Partners Limited........... 4,000,000 * -- 59,740 Highbridge Capital Corporation...... 15,000,000 1 -- 224,025 Houston Fire "B".................... 4,000,000 * -- 59,740 Houston Municipal................... 2,000,000 * -- 29,870 HSBC Securities Inc................. 7,100,000 * -- 106,038 Idanta Partners Ltd................. 8,000,000 * 100,000 119,480 Idanta Partners Ltd. Retirement Plan 500,000 * -- 7,467 Income Fund of America, Inc., The 112,500,000 9 -- 1,680,187 Issa, Mr. Pierre & Mrs. Claude...... 80,000 * -- 1,194 J.P. Morgan & Co. Incorporated...... 29,000,000 2 -- 433,115 Jatyco Inc. -- No. 2 a/c............ 120,000 * -- 1,792 Kensington Value Fund LLC........... 1,000,000 * -- 14,935 Lagunitas Partners LP............... 200,000 * -- 2,987 LDG Limited......................... 1,500,000 * -- 22,402 Levin Charitable Trust.............. 40,000 * -- 597 Libertyview Fund LLC................ 300,000 * -- 4,480 Libertyview Plus Fund............... 8,550,000 * -- 127,097 LLT Limited......................... 810,000 * -- 12,907 Lombard Odier & Cie................. 1,814,000 * -- 27,092 Loomis Sayles Fixed Income Fund..... 1,250,000 * -- 18,668 Loomis Sayles High Yield Fixed Income Fund..................... 400,000 * -- 5,974 Loomis Sayles Offshore High Yield... 2,500,000 * -- 37,337 Maine State Retirement System....... 3,500,000 * -- 52,272 Marsh & McLennan Companies Inc...... 360,000 * -- 5,376 McMahan Securities Company, L.P..... 542,000 * -- 8,094 Mellon Bank NA, Trustee for General Motors Employees Domestic Group Pension Trust.... 2,500,000 * -- 37,337 Merrill Lynch International Ltd..... 14,305,000 1 -- 213,645 Merrill Lynch Pierce Fenner & Smith. 31,174,000 2 -- 465,583 Metropolitan Life fbo General 750,000 * -- 11,201 Motors.......................... Metropolitan Life LS High Yield Series.......................... 1,400,000 * -- 20,909 Millennium Trading Co. L.P.......... 9,000,000 * -- 134,415 Milwaukee County, Wisconsin......... 1,000,000 * -- 14,935 Minneapolis Teachers................ 1,650,000 * -- 24,642 4
5 Museum of Fine Arts, Boston......... $ 590,000 * -- 8,811 NationsBanc Montgomery Securities, LLC................. 10,000,000 * -- 149,350 Nationwide Family of Funds, on behalf of its Nationwide E Equity Income Fund.............. 120,000 * -- 1,792 Nationwide Separate Account Trust Equity Income Fund........ 120,000 * -- 1,792 Navesink Equity Derivative Fund LDC. 11,000,000 * -- 164,285 New England Strategic Income Fund... 3,000,000 * -- 44,805 New Hampshire State Retirement System.......................... 3,100,000 * -- 46,298 New York City Employees' Retirement Plan................. 2,425,000 * -- 36,217 New York City Firemen's Retirement Plan................. 2,400,000 * -- 35,844 New York City Teachers Retirement System............... 9,650,000 * -- 144,122 New York State Electric & Gas Ret. Ben. Plan.................. 2,000,000 * -- 29,870 Nike Co............................. 400,000 * -- 5,974 Northwestern Mutual Life Insurance Company, The (includes $1,000,000 in principal amount held by The Northwestern Mutual Life Insurance Company Group Annuity Separate Account)....... 8,000,000 * (4) 119,480 Oakmont Holdings Limited............ 40,000 * -- 597 Orange County Retirement............ 2,250,000 * -- 33,603 Orrington International Fund Ltd.... 2,238,000 * -- 33,424 Orrington Investments LP............ 3,762,000 * -- 56,185 Palladin Overseas Fund Ltd.......... 1,500,000 * -- 22,402 Palladin Partners I, L.P............ 500,000 * -- 7,467 Parker-Hannifin Corporation......... 750,000 * -- 11,201 Partner Reinsurance Co.............. 1,000,000 * -- 14,935 Partners Healthcare Services........ 2,100,000 * -- 31,363 Pension Reserves Investment Trust 2,000,000 * -- 29,870 Promutual........................... 2,540,000 * -- 37,934 Putnam Balanced Retirement Fund 2,590,000 * -- 38,681 Putnam Convertible Income - Growth Trust.................... 35,563,000 3 -- 531,133 Putnam Convertible Opportunities and Income Trust................ 1,945,000 * -- 29,048 Putnam Equity Income Fund........... 3,780,000 * -- 56,454 Putnam Funds Trust -- Putnam 245,000 * -- 3,659 High Yield Total Return Fund.... Putnam High Income Convertible and Bond Fund................... 4,000,000 * -- 59,740 Putnam Variable Trust -- Putnam VT The George Putnam Fund of Boston....................... 100,000 * -- 1,493 Q Investments, L.P.................. 2,750,000 * -- 41,071 R2 Investments, LDC................. 6,990,000 * -- 104,395 Raytheon Master Trust............... 4,250,000 * -- 63,473 5
6 Reliant Trading..................... $ 1,250,000 * 125,000 18,668 Rhode Island Retirement............. 9,625,000 * -- 143,749 Rohne-Poulenc Rorer Inc. Pension Plan............................ 800,000 * -- 11,948 Salomon Brothers Capital Structure Arbitrage Fund........ 6,000,000 * (5) 89,610 Salomon Brothers Equity Arbitrage Finance Ltd Fund................ 2,000,000 * (5) 29,870 Salomon Smith Barney, Inc........... 5,060,000 * (5) 75,571 Sanders, Mark and Cynthia........... 40,000 * -- 597 SG Cowen Securities Corporation..... 27,050,000 2 -- 403,991 Shepherd Investments International, Ltd.............. 33,465,000 3 -- 499,799 Shepherd Trading Limited............ 1,250,000 * -- 18,668 SoundShore Holdings Ltd............. 350,000 * -- 5,227 SoundShore Opportunity Holding Fund Ltd........................ 2,900,000 * -- 43,311 Southern Farm Bureau Life Insurance Co.................... 1,500,000 * 60,000 22,402 State of Connecticut Fund "F"....... 5,000,000 * -- 74,675 Susquehanna Capital Group........... 19,850,000 2 -- 296,459 Talwar Trading & Investments Ltd. 120,000 * -- 1,792 Teamsters Affiliates Pension Plan... 2,425,000 * -- 36,217 Teamsters Retirement and Family Protection...................... 400,000 * -- 5,974 Tower, Peter & Elizabeth (Tower Foundation)..................... 150,000 * -- 2,240 TQA Arbitrage Fund, L.P............. 4,500,000 * -- 67,207 TQA Leverage Fund, L.P.............. 3,000,000 * -- 44,805 TQA Vantage Fund, Ltd............... 5,500,000 * -- 82,142 TQA Vantage Plus, Ltd............... 1,500,000 * -- 22,402 Tribeca Investments L.L.C........... 5,000,000 * (6) 74,675 UA General Officers Retirement Plan. 50,000 * -- 746 UA Local Union Officers & Employees Pension............... 400,000 * -- 5,974 UA Office Employees Retirement Plan. 25,000 * -- 373 UFCW................................ 500,000 * -- 7,467 United Mine Workers................. 4,900,000 * -- 73,181 University of Rochester............. 590,000 * -- 8,811 Vivaldi Investments Limited ........ 160,000 * -- 2,389 World Bank "B"...................... 1,125,000 * -- 16,801 Worldwide Transactions Ltd.......... 880,000 * 8,555 13,142 Zazove Aggressive Growth Fund, L.P.. 850,000 * -- 12,694 Zazove Convertible Fund, L.P........ 3,200,000 * -- 47,792 Zazove Global Convertible Fund, L.P. 345,000 * -- 5,152 - -------------------------- * Less than one percent. (1) The percent of total outstanding Debentures held by each Selling Securityholder is calculated based on the aggregate principal amount of Debentures originally issued by the Company, and does not take into account conversions, exchanges or other transactions by the Selling Securityholders which may reduce the aggregate principal amount of Debentures currently outstanding. 6
7 (2) The shares of Common Stock registered hereby are calculated on an "as converted" basis using the conversion rate described on the cover page of this Prospectus. (3) Goldman, Sachs & Co. was one of the Initial Purchasers in the private placement of the Debentures by the Company on February 18, 1998. Goldman, Sachs & Co. also holds $2,572,000 principal amount of Debentures, convertible into 38,412 shares of Common Stock, which are not offered hereby. (4) In the ordinary course of business, Northwestern Mutual Investment Services, Inc., Robert W. Baird & Co. Incorporated, Baird/Mark Capital Group, and MGIC Mortgage Securities Corporation, each of which is a broker-dealer and affiliated with The Northwestern Mutual Life Insurance Company, may, from time to time, have acquired or disposed of, or may in the future acquire or dispose of, securities of the Company, for such broker-dealers' own accounts or for the accounts of others. Other affiliates of The Northwestern Mutual Life Insurance Company may, in the ordinary course of business, effect transactions in the securities of the Company. Only security holdings of The Northwestern Mutual Life Insurance Company are reflected. The Northwestern Mutual Life Insurance Company and its affiliates may, in the ordinary course of business, take part in transactions involving the real property of the Company. (5) Salomon Brothers Asset Management Inc. ("SBAM") acts as discretionary investment advisor with respect to the noted accounts that hold the debentures. Accordingly, SBAM may be deemed to be the beneficial owner of such debentures. SBAM also acts as discretionary investment advisor with respect to the Gaguine Family Trust, which holds 4,000 shares of the Company's common stock. Accordingly, SBAM may be deemed to be the beneficial owner of such shares. (6) Tribeca Investments L.L.C. also holds $4,195,000 principal amount of Debentures, convertible into 62,652 shares of Common Stock, which are not offered hereby. Unless otherwise indicated, none of the Selling Securityholders has, or within the past three years has had, any position, office or other material relationship with the Company or any of its affiliates. Because the Selling Securityholders may, pursuant to this Prospectus, sell all or some portion of the Debentures or the Registrable Securities, no estimate can be given as to the amount of the Debentures or the Registrable Securities that will be held by the Selling Securityholders upon termination of any such sales. In addition, the Selling Securityholders identified above may have sold, transferred or otherwise disposed of all or a portion of their Debentures, in transactions exempt from the registration requirements of the Securities Act, since the date on which they provided the information regarding their Debentures. See "Plan of Distribution." The Debentures were originally issued by the Company in a private placement on February 18, 1998 to the Initial Purchasers and were subsequently sold by the Initial Purchasers, in transactions exempt from the registration requirements of the Securities Act, to persons reasonably believed by such Initial Purchasers to be "qualified institutional buyers" (as defined in Rule 144A under the Securities Act). Generally, only Selling Securityholders identified above who beneficially own the Debentures set forth opposite each such Selling Securityholder's name in the foregoing table may sell such debentures pursuant to the Shelf Registration Statement. The Company may from time to time, in accordance with the Registration Rights Agreement, include additional Selling Securityholders in supplements or amendments to this Prospectus. THE DATE OF THIS PROSPECTUS SUPPLEMENT IS DECEMBER 22, 1999 7