Material Event (Form 8-K)

ITEM 8.01. Other Events.

As previously disclosed, on August 6, 2026, DoubleVerify Holdings, Inc., a Delaware corporation (the "Company"), entered into an Agreement and Plan of Merger (as the same may be amended, modified or supplemented from time to time in accordance with its terms, the "Merger Agreement") with Neptune BidCo US Inc., a Delaware corporation ("Parent"), and Wallace Merger Sub Inc., a Delaware corporation and a direct, wholly owned subsidiary of Parent ("Merger Sub"). Pursuant to, and subject to the terms and conditions set forth in, the Merger Agreement, Merger Sub will merge with and into the Company, with the Company surviving the merger and continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). Parent is the parent company of The Nielsen Company (US), LLC.

This Current Report on Form 8-K is being filed to amend and supplement the information in the definitive proxy statement filed by the Company with the Securities and Exchange Commission ("SEC") on September 29, 2026, and sent by the Company to its stockholders commencing on September 29, 2026 (the "Proxy Statement"). The information contained in this Current Report on Form 8-K is incorporated by reference into the Proxy Statement. All page references in this Current Report on Form 8-K are to pages in the Proxy Statement. Terms used in this Current Report on Form 8-K, but not otherwise defined herein, have the meanings ascribed to such terms in the Proxy Statement.

To the extent that information in this Current Report on Form 8-K differs from, or updates information contained in, the Proxy Statement, the information in this Current Report on Form 8-K shall supersede or supplement the information in the Proxy Statement. Except as otherwise described in this Current Report on Form 8-K or the documents referred to, contained in or incorporated by reference in this Current Report on Form 8-K, the Proxy Statement, the annexes to the Proxy Statement and the documents referred to, contained in or incorporated by reference in the Proxy Statement are not otherwise modified, supplemented or amended.

The supplemental information herein should be read in conjunction with the Proxy Statement, which we urge you to read in its entirety. Nothing in this Current Report on Form 8-K shall be deemed an admission of the legal necessity or materiality of any of the disclosures set forth herein. For clarity, new text within restated disclosures from the Proxy Statement is highlighted with bold, underlined text, while deleted text is bold and stricken-through.

If you have not already submitted a proxy for use at the Special Meeting, you are urged to do so promptly. This Current Report on Form 8-K does not affect the validity of any proxy card or voting instructions that the Company's stockholders may have previously received or delivered. No action is required by any stockholder of the Company who has previously delivered a proxy or voting instructions and who does not wish to revoke or change such proxy or voting instructions.

SUPPLEMENTAL DISCLOSURES TO THE PROXY STATEMENT

1.                  The fourth paragraph under the section captioned "Summary - Regulatory Approvals Required for the Merger" of the Proxy Statement set forth on Page 12 is hereby supplemented by amending and restating such paragraph as follows:

On September 3, 2026, notification and report forms were filed by the parties with certain foreign merger control authorities under the Antitrust Laws and competition laws of Cyprus, Germany and Morocco, and a draft notification was submitted to the Australian Competition and Consumer Commission (the "ACCC"). On September 21, 2026, the parties' formal notification was lodged with the ACCC. On October 5, 2026, the Merger received clearance from the German Federal Cartel Office (Bundeskartellamt). On October 7, 2026, the Merger received clearance from the Commission for the Protection of Competition of the Republic of Cyprus. On October 13, 2026, the Merger received clearance from the ACCC. Under the Competition and Consumer Act 2010 (Cth), the parties may not complete the Merger until 14 calendar days have elapsed following publication of the ACCC's determination and reasons on the ACCC's Acquisitions Register, during which period the parties or third parties with standing may apply to the Australian Competition Tribunal for review of the determination. Assuming no such application for review is made, the parties may complete the Merger following the expiration of such 14-day period in accordance with the Competition and Consumer Act 2010 (Cth). Also on October 13, 2026, the Merger received clearance from the Moroccan Competition Council (Conseil de la Concurrence). As of the date of this Current Report on Form 8-K, all reviews pursuant to the Antitrust Laws and competition laws of Australia, Cyprus, Germany and Morocco have been completed, subject to the expiration of the Australian Competition Tribunal review period described above.