PROSPECTUS SUPPLEMENT (To Prospectus Dated February 26, 2001) Filed Pursuant to Rule 424(b)(3) Registration Statement No. 333-55386 $850,000,000 OMNICOM GROUP INC. Liquid Yield Option(TM) Notes due 2031 (Zero Coupon-Senior) This prospectus supplement relates to the resale by the selling securityholders of Liquid Yield Option(TM) Notes (Zero Coupon -- Senior) due 2031 (the "LYONs") of Omnicom Group Inc. and the shares of common stock issuable upon the conversion and/or redemption of the LYONs. This prospectus supplement should be read in conjunction with the prospectus dated February 26, 2001, which is to be delivered with this prospectus supplement. All capitalized terms used but not defined in the prospectus supplement shall have the meanings given 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 LYONs were originally issued by us and sold by Merrill Lynch, Pierce, Fenner & Smith Incorporated in a transaction exempt from the registration requirements of the Securities Act to persons reasonably believed by Merrill Lynch to be "qualified institutional buyers" (as defined by Rule 144A under the Securities Act). The selling securityholders (which term includes their transferees, pledgees, donees or successors) may from time to time offer and sell pursuant to this prospectus, as amended or supplemented, any and all of the LYONs and the shares of common stock issuable upon conversion and/or redemption of the LYONs. Set forth below are the names of each selling securityholder, the principal amount of LYONs that may be offered by such selling securityholder pursuant to this prospectus, as amended or supplemented, and the number of shares of common stock into which such LYONs are convertible. Unless set forth below, none of the selling securityholders has had a material relationship with us or any of our predecessors or affiliates within the past three years. The following table sets forth certain information received by us on or prior to May 31, 2001. However, any or all of the LYONs or common stock listed below may be offered for sale pursuant to this prospectus, as amended or supplemented, by the selling securityholders from time to time. Accordingly, no estimate can be given as to the amounts of LYONs or common stock that will be held by the selling securityholders upon consummation of any such sales. In addition, the selling securityholders identified below may have sold, transferred or otherwise disposed of all or a portion of their LYONs since the date on which the information regarding their LYONs was provided, in transactions exempt from the registration requirements of the Securities Act. Common Stock Aggregate Principal Amount Percentage Beneficially Common Stock of LYONs at Maturity of LYONs Owned Prior Registered Name that may be Sold Outstanding to Conversion Hereby(1) ------------------------------------------------- -------------------------- ----------- ------------- ----------- AAM/Zazove Institutional Income Fund L.P. (BS) .... $ 1,000,000 * -- 9,090 AFTRA Health Fund ................................. 475,000 * -- 4,317 AIG SoundShore Holdings Ltd. ...................... 6,451,000 * -- 58,639 AIG SoundShore Opportunity Holding Fund Ltd. ...... 7,328,000 * -- 66,611 AIG SoundShore Strategic Holding Fund Ltd. ........ 4,221,000 * -- 38,368 Allstate Insurance Company ........................ 1,700,000 * 85,300 15,453 Allstate Life Insurance Company ................... 2,300,000 * 85,300 20,907 American Country Insurance Company ................ 600,000 * -- 5,454 American Founders Life Insurance Company .......... 100,000 * -- 909 American Pioneer Life Ins. Co. of New York ........ 90,000 * -- 818 American Progressive Life and Health Ins. Co. of New York ....................................... 90,000 * -- 818 American Public Entity Excess Pool ................ 60,000 * -- 545 AmWest Surety Insurance Company ................... 270,000 * -- 2,454 Arpeggio Fund, L.P. ............................... 1,000,000 * -- 9,090 Baltimore Life Insurance Company .................. 300,000 * -- 2,727 BCS Life Insurance Company ........................ 650,000 * -- 5,908 Bear, Stearns & Co., Inc. ......................... 2,500,000 * -- 22,725 Brown & Williamson Tobacco Master Retirement Trust ............................... 100,000 * -- 909 Buckeye State Mutual Insurance Company ............ 30,000 * -- 272 Common Stock Aggregate Principal Amount Percentage Beneficially Common Stock of LYONs at Maturity of LYONs Owned Prior Registered Name that may be Sold Outstanding to Conversion Hereby(1) ------------------------------------------------- -------------------------- ----------- ------------- ----------- Catholic Mutual Relief Society of America ......... 500,000 * -- 4,545 Catholic Mutual Relief Society of America Retirement Plan & Trust ........................ 300,000 * -- 2,727 Catholic Relief Insurance Company of America ...... 600,000 * -- 5,454 Celina Mutual Insurance Company ................... 25,000 * -- 227 Central States Health & Life Company of Omaha ..... 220,000 * -- 1,999 Chicago Mutual Insurance Company .................. 70,000 * -- 636 Chrysler Insurance Company ........................ 4,000,000 * -- 36,360 The Class IC Company, Ltd. ........................ 2,000,000 * -- 18,180 Colonial Life Insurance Company of Texas .......... 25,000 * -- 227 Commonwealth Dealers - CDLIC ...................... 200,000 * -- 1,818 Concord Life Insurance Company .................... 140,000 * -- 1,272 Condor Insurance Company .......................... 180,000 * -- 1,636 Credit Suisse First Boston Corporation ............ 200,000 * -- 1,818 CSA Fraternal Life Insurance Company .............. 130,000 * -- 1,181 Cumberland Mutual Fire Insurance Company .......... 220,000 * -- 1,999 Dakota Truck Underwriters ......................... 25,000 * -- 227 D.E. Shaw Investments, L.P. ....................... 800,000 * -- 7,272 D.E. Shaw Valence, L.P. ........................... 3,200,000 * -- 29,088 Educators Mutual Life Insurance Company ........... 250,000 * -- 2,272 Farmers Home Mutual Insurance Company ............. 450,000 * -- 4,090 Federated Rural Electric Insurance Exchange ....... 360,000 * -- 3,272 Fidelity Financial Trust: Fidelity Convertible Securities Fund ................................ 6,000,000 * -- 54,540 First Dakota Indemnity Company .................... 20,000 * -- 181 First Mercury Insurance Company ................... 620,000 * -- 5,635 First Union National Bank ......................... 21,000,000 2.47% -- 190,890 Forest Alternative Strategies Fund II LP A5M ...... 150,000 * -- 1,363 Forest Fulcrum Fund L.P. .......................... 1,200,000 * -- 10,908 Forest Global Convertible Fund A5 ................. 5,850,000 * -- 53,176 Fort Dearborn Life Insurance Company .............. 250,000 * -- 2,272 Gaia Offshore Master Fund Ltd. .................... 12,500,000 1.47% -- 113,625 GLG Global Convertible Fund ....................... 1,650,000 * -- 14,998 GLG Global Convertible Ucits Fund ................. 350,000 * -- 3,181 GLG Market Neutral Fund ........................... 2,500,000 * -- 22,725 Goldman Sachs and Company ......................... 550,000 * -- 4,999 Goodville Mutual Casualty Company ................. 50,000 * -- 454 Grain Dealers Mutual Insurance .................... 160,000 * -- 1,454 Green Tree Perpetual Assurance Company ............ 300,000 * -- 2,727 Guaranty Income Life Insurance Company ............ 450,000 * -- 4,090 Guarantee Trust Life Insurance Company ............ 1,000,000 * -- 9,090 Hamilton Partners Limited ......................... 20,000,000 2.35% -- 181,800 Hannover Life Reassurance Company of America ...... 500,000 * -- 4,545 HFR Master Fund LTD ............................... 200,000 * -- 1,818 HighBridge International LLC ...................... 30,000,000 3.53% -- 272,700 Holy Family Society ............................... 90,000 * -- 818 IMF Convertible Fund .............................. 700,000 * -- 6,363 Integrity Mutual Insurance Company ................ 300,000 * -- 2,727 Investcorp - SAM Fund Ltd. ........................ 3,200,000 * -- 29,088 ISBA Mutual Insurance Company ..................... 225,000 * -- 2,045 J.P. Morgan Securities, Inc. ...................... 39,000,000 4.59% -- 354,510 Kanawha Insurance Company ......................... 250,000 * -- 2,272 KBC Financial Products USA ........................ 2,000,000 * -- 18,180 Landmark Life Insurance Company ................... 60,000 * -- 545 Lebanon Mutual Insurance Company .................. 100,000 * -- 909 LLT Limited ....................................... 400,000 * -- 3,636 Loyal Christian Benefit Association ............... 80,000 * -- 727 Lyxor Master Fund, c/o Forest Investment Management L.L.C ............................... 1,600,000 * -- 14,544 Mainstay Convertible Fund ......................... 7,000,000 * -- 63,630 Mainstay VP Convertible Portfolio ................. 1,600,000 * -- 14,544 Marquette Indemnity and Life Insurance Comp ....... 80,000 * -- 727 McMahan Securities Co. L.P. ....................... 100,000 * -- 909 Medico Life Insurance Company ..................... 800,000 * -- 7,272 Medmare Insurance Company ......................... 500,000 * -- 4,545 Merrill Lynch, Pierce, Fenner & Smith Incorporated(2) ................................ 65,225,000 7.67% -- 592,895 Michigan Professional Insurance Exchange .......... 110,000 * -- 999 Mid America Life Insurance Company ................ 100,000 * -- 909 Middle Cities Risk Management Trust ............... 200,000 * -- 1,818 Midwest Security Life ............................. 280,000 * -- 2,545 Morgan Stanley & Co. Incorporated(3) .............. 15,000,000 1.76% -- 136,350 MSC Life .......................................... 50,000 * -- 454 Common Stock Aggregate Principal Amount Percentage Beneficially Common Stock of LYONs at Maturity of LYONs Owned Prior Registered Name that may be Sold Outstanding to Conversion Hereby(1) ------------------------------------------------- -------------------------- ----------- ------------- ----------- Mutual Protective Insurance Company ............... 1,100,000 * -- 9,999 National Mutual Insurance Company ................. 30,000 * -- 4,545 NCMIC ............................................. 500,000 * -- 272 New Era Life Insurance Company .................... 300,000 * -- 2,727 New York Life Separate Account #7 ................. 900,000 * -- 8,181 Nomura Securities International, Inc. ............. 15,000,000 1.76% 307,158 136,350 Oak Casualty Insurance Company .................... 40,000 * -- 363 Onyx Fund Holdings, LDC ........................... 12,000,000 1.41% -- 109,080 PHICO Insurance Company ........................... 600,000 * -- 5,454 Physicians Mutual Insurance Company ............... 600,000 * -- 5,454 Pioneer Insurance Company ......................... 80,000 * -- 727 Premera Blue Cross ................................ 1,500,000 * -- 13,635 R2 Investments, LDC ............................... 122,000,000 14.35% -- 1,108,980 Republic Mutual Insurance Company ................. 15,000 * -- 136 Rhapsody Fund, LP. ................................ 3,700,000 * -- 33,633 Royal Bank of Canada .............................. 6,000,000 * 95,033 54,540 Sagamore Hill Hub Fund Ltd. ....................... 14,500,000 1.71% -- 131,805 Salomon Smith Barney Inc. ......................... 3,000,000 * -- 27,270 SAM Investments LDC ............................... 50,000,000 5.88% -- 454,500 San Diego County Employees Retirement Association . 2,800,000 * -- 25,452 St. Albans Partners Ltd. .......................... 13,000,000 1.53% -- 118,170 Standard Mutual Insurance Company ................. 300,000 * -- 2,727 State National Insurance Company .................. 120,000 * -- 1,090 Sylvan IMA Ltd., c/o Forest Investment Management L.L.C ............................... 800,000 * -- 7,272 Texas Builders Insurance Company .................. 120,000 * -- 1,090 Texas Hospital Insurance Exchange ................. 25,000 * -- 227 Transguard Insurance Company of America, Inc. ..... 900,000 * -- 8,181 Tribeca Investments LLC ........................... 25,000,000 2.94% -- 227,250 United National Insurance Company ................. 850,000 * -- 7,726 Western Home Insurance Company .................... 180,000 * -- 1,636 West Virginia Fire Insurance Company .............. 10,000 * -- 90 Westward Life Insurance Company ................... 180,000 * -- 1,636 White River Securities L.L.C ...................... 2,500,000 * -- 22,725 Wisconsin Lawyers Mutual Insurance company ........ 200,000 * -- 1,818 Wisconsin Mutual Insurance Company ................ 140,000 * -- 1,272 World Insurance Company ........................... 250,000 * -- 2,272 All other holders of LYONs or future transferees, pledgees, donees or successors of any such holders(4)(5) .................................. 283,250,000 46.58% -- 2,574,769 ------------ ------ ------- --------- Total .......................................... $850,000,000 100.00% 572,791 7,726,500 ============ ====== ======= ========= * Less than 1% ---------- (1) Assumes conversion of all of the holder's LYONs at a conversion rate of 9.09 shares of common stock per $1,000 principal amount at maturity of the LYONs. However, this conversion rate will be subject to adjustment as described under "Description of the LYONs -- Conversion Rights." As a result, the amount of common stock issuable upon conversion of the LYONs may increase or decrease in the future. (2) Merrill Lynch, Pierce, Fenner & Smith Incorporated was the initial purchaser in the private placement on February 7, 2001 in which the LYONs were originally issued. Merrill Lynch has advised us that it is not aware of any position, office or directorship relationship that it has had with Omnicom or its affiliates. However, Merrill Lynch has advised us that it may have, from time to time, acted in a financial investment advisory capacity to Omnicom. (3) Morgan Stanley & Co. Incorporated was the initial purchaser in the offering of $230,000,000 aggregate principal amount of 2 1/4% convertible subordinated debentures due 2013 on January 6, 1998 by Omnicom. (4) Information about other selling securityholders will be set forth in prospectus supplements, if required. (5) Assumes that any other holders of LYONs, or any future transferees, pledgees, donees or successors of or from any such other holders of LYONs, do not beneficially own any common stock other than the common stock issuable upon conversion of the LYONs at the initial conversion rate. The preceding table has been prepared based upon information furnished to us by the selling securityholders named in the table. From time to time, additional information concerning ownership of the LYONs and common stock may rest with certain holders thereof not named in the preceding table, with whom we believe we have no affiliation. Information about the selling securityholders may change from over time. Any changed information will be set forth in prospectus supplements. ---------- The date of this Prospectus Supplement is June 1, 2001. ---------- (TM) Trademark of Merrill Lynch & Co., Inc.