# EDGAR Filing Document

**Accession Number:** 0001595974
**File Stem:** 0001999371-26-008636
**Filing Date:** 2026-4
**Character Count:** 6463
**Document Hash:** e4153dcd8173b2c5d012aa6939b38704
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001999371-26-008636.hdr.sgml**: 20260421

**ACCESSION NUMBER**: 0001999371-26-008636

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20260421

**DATE AS OF CHANGE**: 20260421

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MAGNITE, INC.
- **CENTRAL INDEX KEY:** 0001595974
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
- **ORGANIZATION NAME:** 06 Technology
- **EIN:** 208881738
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-36384
- **FILM NUMBER:** 26880041

**BUSINESS ADDRESS:**
- **STREET 1:** 1250 BROADWAY
- **STREET 2:** 9TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **BUSINESS PHONE:** 212-243-2769

**MAIL ADDRESS:**
- **STREET 1:** 1250 BROADWAY
- **STREET 2:** 9TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** RUBICON PROJECT, INC.
- **DATE OF NAME CHANGE:** 20140106

**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**

**(Amendment No.)** 

Filed by the Registrant ☒ <br> Filed by a Party other than the Registrant ☐

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| | |
|:---|:---|
| Check the appropriate box: | 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 Pursuant to § 240.14a-12 |

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**<u>MAGNITE, INC.</u>**

(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 all boxes that apply): <br> <br> ☒ No fee required

☐ Fee paid previously with preliminary materials <br>☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

**Important Notice Regarding the Availability of Proxy Materials for**

**the Annual Meeting of Stockholders of**

![](proxycard1002.jpg)

**TO BE HELD ON:**

**Monday, June 8, 2026, at 12:00 PM Eastern Time**

**By Virtual Meeting via live webcast**

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|:---|
| **COMPANY NUMBER** |
| **ACCOUNT NUMBER** |
| **CONTROL NUMBER** |

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**This communication presents only an overview of the more complete proxy materials that are available to you on the Internet.** We encourage you to access and review all of the important information contained in the proxy materials before voting.

If you want to receive a paper or e-mail copy of the proxy materials you must request one. There is no charge to you for requesting a copy. To facilitate timely delivery please make the request as instructed below before May 22, 2026. Unless requested, you will not otherwise receive a paper or e-mail copy.

**Please visit <u>www.astproxyportal.com/ast/18899</u>, where the following materials are available for view:**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**•** Notice of Meeting

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**•** Proxy statement

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**•** Proxy card

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**•** 2025 Annual Report

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| | | |
|:---|:---|:---|
| **TO REQUEST MATERIALS** | **TO REQUEST MATERIALS** | **TELEPHONE: 1-888-Proxy-NA (1-888-776-9962) or +1-201-299-6210 (worldwide)** |
| **FOR THIS AND/OR FUTURE** | **FOR THIS AND/OR FUTURE** | **E-MAIL: help@equiniti.com** |
| **MEETINGS:** | **MEETINGS:** | **WEBSITE: <u>us.astfinancial.com/OnlineProxyVoting/ProxyVoting/RequestMaterials</u>** |
| **TO VOTE:** | ![](proxycard1001.jpg) | **ONLINE:** To access your online proxy card, please visit **<u>www.voteproxy.com</u>** and follow the on-screen instructions or scan the QR code with your smartphone. You may enter your voting instructions at <u>www.voteproxy.com</u> up until 11:59 PM Eastern Time the day before the meeting date. <br> **VIRTUALLY AT THE MEETING:** The Company will be hosting the meeting virtually this year. To attend the virtual meeting, please visit <u>edge.media-server.com/mmc/p/mxrvvt7t</u> and be sure to have your control number available. The meeting password is **magnite2026**. <br> **TELEPHONE:** Call toll-free **1-800-PROXIES (1-800-776-9437)** in the United States or **+1-201-299-4446** worldwide from any touch-tone telephone and follow the instructions. Have this notice available when you call. <br> **MAIL:** You may request a proxy card by following the instructions above. |

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| | | |
|:---|:---|:---|
|  | &nbsp;&nbsp;1. | Election of Class III Directors: |
|  |  | 1A Paul Caine |
|  |  | 1B Doug Knopper |
|  |  | 1C David Pearson |
|  | &nbsp;&nbsp;2. | Ratification of the selection of Deloitte & Touche LLP as the Company's independent registered public accounting firm for the current fiscal year. |
|  | &nbsp;&nbsp;3. | Approval, on an advisory basis, of the compensation of the Company's named executive officers. |
|  | &nbsp;&nbsp;4. | Advisory vote on the frequency of future advisory votes on the compensation of the Company's named executive officers. |
|  | &nbsp;&nbsp;5. | To transact such other business as may properly come before the meeting or any postponements or adjournments thereof. |
|  | &nbsp;&nbsp;**THE BOARD OF DIRECTORS RECOMMENDS A VOTE "FOR" THE ELECTION OF DIRECTORS, "FOR" PROPOSALS 2 AND 3, AND "1 YEAR" FOR PROPOSAL 4.** | &nbsp;&nbsp;**THE BOARD OF DIRECTORS RECOMMENDS A VOTE "FOR" THE ELECTION OF DIRECTORS, "FOR" PROPOSALS 2 AND 3, AND "1 YEAR" FOR PROPOSAL 4.** |
| **Please note that this is not a votable ballot. You cannot use this notice to vote by mail.** |  |  |

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