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  4. [Form 4] MAGNITE, INC. Insider Trading Activity

Magnite CTO sells 6,414 shares in planned trades

Magnite’s chief technology officer executed pre-planned sales totaling 6,414 shares under a Rule 10b5-1 trading plan.

Filing Impact
(Neutral)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) reported that its Chief Technology Officer, David Buonasera, sold a total of 6,414 shares of common stock in two open market or private transactions under a Rule 10b5-1 trading plan. The sales occurred on September 1, 2026 and September 2, 2026 at prices of $23.42 and $25.00 per share, respectively.

Positive

  • None.

Negative

  • None.
Insider Buonasera David
Role CHIEF TECHNOLOGY OFFICER
Sold 6,414 shs ($152K)
Type Security Shares Price Value
Sale Common Stock F1 1,043 $25.00 $26K
Sale Common Stock F1 5,371 $23.42 $126K
Holdings After Transaction: Common Stock — 246,320 shares (Direct)
Footnotes (1)
  1. F1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 11, 2025.
Shares sold on September 1, 2026 5,371 shares Common stock sale by CTO in open market or private transaction
Shares sold on September 2, 2026 1,043 shares Common stock sale by CTO in open market or private transaction
Total shares sold 6,414 shares Aggregate of both reported sales of Magnite common stock
Sale price on September 1, 2026 $23.42 per share Price for 5,371 shares of common stock sold
Sale price on September 2, 2026 $25.00 per share Price for 1,043 shares of common stock sold
Rule 10b5-1 plan adoption date September 11, 2025 Trading plan under which the reported sales were effected
Rule 10b5-1 trading plan regulatory
"The reported transaction was effected pursuant to a Rule 10b5-1 trading plan"
A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.
open market or private transaction financial
"Sale in open market or private transaction"

FAQ

What insider transactions did MGNI disclose in this Form 4?
The filing reports that Chief Technology Officer David Buonasera sold a total of 6,414 shares of Magnite common stock in two open market or private transactions on September 1–2, 2026.

How many MGNI shares did the CTO sell on each date?
On September 1, 2026, the CTO sold 5,371 shares of Magnite common stock at $23.42 per share. On September 2, 2026, he sold an additional 1,043 shares at $25.00 per share.

Were the MGNI insider sales made under a Rule 10b5-1 trading plan?
Yes. A footnote states the reported transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by David Buonasera on September 11, 2025.

What is the total number of MGNI shares sold in this Form 4?
Across both transactions, the Chief Technology Officer sold 6,414 shares of Magnite common stock, based on sales of 5,371 shares on September 1, 2026 and 1,043 shares on September 2, 2026.

What prices were received for the MGNI shares sold?
The shares of Magnite common stock were sold at per-share prices of $23.42 on September 1, 2026 for 5,371 shares and $25.00 on September 2, 2026 for 1,043 shares.

Does the Form 4 show remaining MGNI holdings for the CTO after these sales?
The transactions are reported as direct ownership, but the rows list no post-transaction share totals for the Chief Technology Officer, so remaining holdings are not detailed in this filing’s data.

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SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
X
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Buonasera David
(Last)(First)(Middle)
C/O MAGNITE, INC.
1250 BROADWAY, 9TH FLOOR
(Street)
NEW YORK NEW YORK 10001
(City)(State)(Zip)
UNITED STATES
(Country)		2. Issuer Name and Ticker or Trading Symbol
MAGNITE, INC. [ MGNI ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director10% Owner
XOfficer (give title below)Other (specify below)
CHIEF TECHNOLOGY OFFICER
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
09/01/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Common Stock09/01/2026S(1)5,371D$23.42247,363D
Common Stock09/02/2026S(1)1,043D$25246,320D
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Explanation of Responses:
1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 11, 2025.
Remarks:
/s/ Aaron Saltz, attorney-in-fact09/03/2026
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR