Executive Change · Shareholder Vote

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549     FORM 8-K       CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934   Date of Report (Date of earliest event reported): January 28, 2026       OMNICOM GROUP INC. (Exact Name of Registrant as Specified in its Charter)     New York   1-10551   13-1514814 (State or other jurisdiction of incorporation)   (Commission File Number)   (IRS Employer Identification No.)   280 Park Avenue , New York , NY   10017 (Address of principal executive offices)   (Zip Code)   Registrant’s telephone number, including area code: ( 212 )  415-3600   Not Applicable (Former name or former address, if changed since last report)     Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:   ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))   Securities registered pursuant to Section 12(b) of the Act:   Title of each class   Trading Symbol   Name of each exchange on which registered Common Stock, par value $0.15 per share   OMC   New York Stock Exchange 0.800% Senior Notes due 2027   OMC/27   New York Stock Exchange 1.400% Senior Notes due 2031   OMC/31   New York Stock Exchange 3.700% Senior Notes due 2032   OMC/32   New York Stock Exchange 2.250% Senior Notes due 2033   OMC/33   New York Stock Exchange   Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).   Emerging growth company ☐   If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐         Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.   (e) On January 28, 2026, the shareholders of Omnicom Group Inc. (the “Company”) approved the Omnicom 2026 Incentive Award Plan (the “Plan”). A more detailed description of the Plan is available in the Company’s definitive proxy statement on Schedule 14A filed with the Securities and Exchange Commission on December 22, 2025 (the “Proxy Statement”) under the heading, “Proposal 1 – Approval of the Omnicom 2026 Incentive Award Plan,” which description is incorporated by reference herein.   The foregoing summary and the description incorporated by reference from the Proxy Statement do not purport to be complete and are qualified in their entirety by reference to the full text of the Plan, a copy of which is included as Exhibit 10.1 hereto and incorporated herein by reference.   Item 5.07. Submission of Matters to a Vote of Security Holders.   (a) The Company held a special meeting of shareholders (the “Special Meeting”) on January 28, 2026. At the Special Meeting, the Company’s shareholders approved the Plan, which is described in more detail in the Proxy Statement.   (b) Proposal 1   The Company’s shareholders approved the Plan as described in the Proxy Statement.   Votes For   Votes Against   Abstentions   Broker Non-Votes 257,022,432   8,600,690   223,223   —   Item 9.01. Financial Statements and Exhibits.   Exhibit Number   Description 10.1   Omnicom 2026 Incentive Award Plan (incorporated by reference to Annex A of the Company’s Definitive Proxy Statement on Schedule 14A, filed on December 22, 2025).       104   The cover page from this Current Report on Form 8-K, formatted in Inline XBRL.   1   SIGNATURES   Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.     Omnicom Group Inc. Date: January 29, 2026       By: /s/ Louis F. Januzzi   Name: Louis F. Januzzi   Title: Senior Vice President, General Counsel and Secretary     2