Company: UAA
Filing Date: 2025-06-26
Form Type: DEFA14A
Source: 0001140361-25-023824
Chunk: 0

Company: Under Armour, Inc.
Filing Date: 2025-06-26
Form: DEFA14A
Chunk 0
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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box:

| ☐ |     | Preliminary Proxy Statement                                                     |
| ☐ |     | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| ☐ |     | Definitive Proxy Statement                                                      |
| ☒ |     | Definitive Additional Materials                                                 |
| ☐ |     | Soliciting Material under §240.14a-12                                           |

UNDER ARMOUR, INC. (Name of registrant as specified in its charter) (Name of person(s) filing proxy statement, if other than the registrant) Payment of Filing Fee (Check the appropriate box):

| ☒ |     | No fee required                                                                                     |
| ☐ |     | Fee paid previously with preliminary materials                                                      |
| ☐ |     | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

<div align='center'>Your Vote Counts! UNDER ARMOUR, INC. ATTN: CORPORATE SECRETARY 101 PERFORMANCE DRIVE BALTIMORE, MARYLAND 21230 UNDER ARMOUR, INC. 2025 Annual Meeting Vote by September 2, 2025 11:59 PM ET You invested in UNDER ARMOUR, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting of Stockholders. This is an important notice regarding the availability of proxy materials for the annual meeting of stockholders to be held on September 3, 2025 at 1:00 PM Eastern Time. Get informed before you vote View the Proxy Statement and Under Armour, Inc.’s Fiscal Year 2025 Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to August 20, 2025. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email