宏盟集团美股招股说明书(2025-12-12版)

Offers to Exchange All of the Outstanding Restricted 4.650% Senior Notes Due 2028 Issued on December2, 2025for Newly Issued and Registered 4.650% Senior Notes Due 2028 All of the Outstanding Restricted 4.750% Senior Notes Due 2030 Issued on December2, 2025for Newly Issued and Registered 4.750% Senior Notes Due 2030 All of the Outstanding Restricted 2.400% Senior Notes Due 2031 Issued on December2, 2025for Newly Issued and Registered 2.400% Senior Notes Due 2031 All of the Outstanding Restricted 5.375% Senior Notes Due 2033 Issued on December2, 2025for Newly Issued and Registered 5.375% Senior Notes Due 2033 All of the Outstanding Restricted 3.375% Senior Notes Due 2041 Issued on December2, 2025for Newly Issued and Registered 3.375% Senior Notes Due 2041 All of the Outstanding Restricted 5.400% Senior Notes Due 2048 Issued on December2, 2025for Newly Issued and Registered 5.400% Senior Notes Due 2048 Omnicom is offering to exchange up to $451,426,000 aggregate principal amount of new 4.650% SeniorNotes due 2028 (the “New 2028 Notes”), $591,859,000 aggregate principal amount of new 4.750% SeniorNotes due 2030 (the “New 2030 Notes”), $457,358,000 aggregate principal amount of new 2.400% SeniorNotes due 2031 (the “New 2031 Notes”), $278,341,000 aggregate principal amount of new 5.375% SeniorNotes due 2033 (the “New 2033 Notes”), $494,331,000 aggregate principal amount of new 3.375% SeniorNotes due 2041 (the “New 2041 Notes”) and $491,657,000 aggregate principal amount of new 5.400% SeniorNotes due 2048 (the “New 2048 Notes”) for outstanding Original Notes of the applicable series. We refer to theNew 2028 Notes, the New 2030 Notes, the New 2031 Notes, the New 2033 Notes, the New 2041 Notes and theNew 2048 Notes, collectively, as the “Exchange Notes.” We refer herein to the Original Notes and the ExchangeNotes, collectively, as the “Notes.” We refer to the offers to exchange, collectively, as the “Exchange Offers.” Table of Contents The terms of each series of Exchange Notes are substantially identical to the terms of the correspondingseries of Original Notes, except that the Exchange Notes will be registered under the Securities Act and thetransfer restrictions and registration rights applicable to the Original Notes will not apply to the ExchangeNotes. Each series of Exchange Notes will be part of the same series as the corresponding series of OriginalNotes and will be issued under the same Indenture (as defined herein). The Exchange Notes will be exchangedfor Original Notes of the corresponding series in minimum denominations of $2,000 and integral multiples of$1,000 in excess thereof. We will not receive any proceeds from the issuance of Exchange Notes in theExchange Offers. You may withdraw tenders of Original Notes at any time prior to the expiration of the Exchange Offers. The Exchange Offers expire at 5:00p.m. NewYork City time on January 13, 2026 unless extended,which we refer to as the “Expiration Date.” We do not intend to list the Exchange Notes on any securities exchange or to seek approval through anyautomated quotation system, and no active public market for the Exchange Notes is anticipated. You should consider carefully the risk factors beginning on page7 of this prospectus beforedeciding whether to participate in the Exchange Offers. Neither the Securities and Exchange Commission, or the “SEC,” nor any state securitiescommission has approved or disapproved of the Exchange Notes or determined if this prospectus istruthful or complete. Any representation to the contrary is a criminal offense. The date of this prospectus is December 12, 2025. Table of Contents Rather than repeat certain information in this prospectus that we have already included in reportsfiled with the SEC, this prospectus incorporates important business and financial information about usthat is not included in or delivered with this prospectus. We will provide this information to you at nocharge upon written or oral request directed to: Omnicom Group Inc.,280 Park Avenue, NewYork,NewYork 10017, Attention: Corporate Secretary; Telephone: (212)415-3600. In order to receive timelydelivery of any requested documents in advance of the Expiration Date, you should make your request nolater than January 6, 2026, which is five fullbusiness days before you must make a decision regarding theExchange Offers. TABLE OF CONTENTS This prospectus may only be used where it is legal to make the Exchange Offers and by a broker-dealerfor resales of Exchange Notes acquired in the Exchange Offers where it is legal to do so. This prospectus and the information incorporated by reference summarize documents and otherinformation in a manner we believe to be accurate, but we refer you to the actual documents for a morecomplete understanding of the information we discuss in this prospectus and the information incorporated byreference. In deciding whether to exchange your Original Notes, you must rely on your own examination ofsuch docume