MGNI SEC Filing News — Magnite, Inc.

Latest SEC filings for Magnite, Inc. (MGNI) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-10-14.

Magnite, Inc., together with its subsidiaries, operates an independent omni-channel sell-side advertising platform in the United States and internationally. The company's platform offers applications and services for sellers of digital advertising inventory, or publishers that own and operate CTV channels, applications, websites, and other digital media properties to manage and monetize their inventory; and for buyers, including advertisers, agencies, agency trading desks, and demand side platfo…
Sector: Communication Services Industry: Advertising Agencies Market Cap: $3.4B CIK: 1595974
20
Total Filings
0
Bullish Classifications
9
Bearish Classifications
11
Insider Transactions
2
Material Events (8-K)
0
Periodic Reports
Rule-based classifications for MGNI currently lean bearish. Of the 20 filing records displayed, 9 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.
MGNI Filing Activity Snapshot 2026-09-10 — 2026-10-14
Insider Transactions (Form 4)
0 buys vs 9 sells
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Form 144 Filing
$1.41M
AARON SALTZ · 2026-09-10
60,000 shares · Form 144
Form 144 Notices
7
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 11 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 11 filings in this group are Form 4s for Magnite, Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 11 insider filings shown, the breakdown is 9 open-market sale and 2 compensation award. 9 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Open-market sale ×9
The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.
Compensation award ×2
Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.
Form 4 Open-market sale Insider Selling 2026-10-14

MGNI insider Caine Paul (Director) sold 12,500 shares (~$316.1K)

Caine Paul, listed as Director at MAGNITE, INC., reported an open-market sale of 12,500 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 12,500 $25.29 $316.1K
Filing: Form 4 (Insider Transaction) Insider: Caine Paul (Director) Shares: 12,500 Est. Value: $316.1K
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-10-02

MGNI insider Form 4 filed for equity award, exercise, or tax withholding

Sullivan Haas (CHIEF ACCOUNTING OFFICER) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code Nature Shares Price Value
A Compensation award 24,641 — —
Filing: Form 4 (Insider Transaction) Insider: Sullivan Haas (CHIEF ACCOUNTING OFFICER) Shares: 24,641
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-10-02

MGNI insider Form 4 filed for equity award, exercise, or tax withholding

Gephart Brian (CHIEF FINANCIAL OFFICER) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code Nature Shares Price Value
A Compensation award 64,682 — —
Filing: Form 4 (Insider Transaction) Insider: Gephart Brian (CHIEF FINANCIAL OFFICER) Shares: 64,682
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-18

MGNI insider Caine Paul (Director) sold 7,500 shares (~$198.8K)

Caine Paul, listed as Director at MAGNITE, INC., reported an open-market sale of 7,500 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 7,500 $26.50 $198.8K
Filing: Form 4 (Insider Transaction) Insider: Caine Paul (Director) Shares: 7,500 Est. Value: $198.8K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-18

MGNI insider Knopper Douglas S (Director) sold 37,337 shares (~$981.2K)

Knopper Douglas S, listed as Director at MAGNITE, INC., reported an open-market sale of 37,337 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 37,337 $26.28 $981.2K
Filing: Form 4 (Insider Transaction) Insider: Knopper Douglas S (Director) Shares: 37,337 Est. Value: $981.2K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-16

MGNI insider Buonasera David (CHIEF TECHNOLOGY OFFICER) sold 1,165 shares (~$28.0K)

Buonasera David, listed as CHIEF TECHNOLOGY OFFICER at MAGNITE, INC., reported an open-market sale of 1,165 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 1,165 $24.00 $28.0K
Filing: Form 4 (Insider Transaction) Insider: Buonasera David (CHIEF TECHNOLOGY OFFICER) Shares: 1,165 Est. Value: $28.0K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-16

MGNI insider Spillane Robert F (Director) sold 10,363 shares (~$246.2K)

Spillane Robert F, listed as Director at MAGNITE, INC., reported an open-market sale of 10,363 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 10,363 $5.17 $53.6K
S Open-market sale 10,363 $23.76 $246.2K
M Option exercise derivative · Stock Option (right to buy) 10,363 — —
Filing: Form 4 (Insider Transaction) Insider: Spillane Robert F (Director) Shares: 10,363 Est. Value: $246.2K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-11

MGNI insider Saltz Aaron (CHIEF LEGAL OFFICER) sold 40,000 shares (~$936.4K)

Saltz Aaron, listed as CHIEF LEGAL OFFICER at MAGNITE, INC., reported an open-market sale of 40,000 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 40,000 $23.41 $936.4K
Filing: Form 4 (Insider Transaction) Insider: Saltz Aaron (CHIEF LEGAL OFFICER) Shares: 40,000 Est. Value: $936.4K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-11

MGNI insider Caine Paul (Director) sold 5,000 shares (~$117.7K)

Caine Paul, listed as Director at MAGNITE, INC., reported an open-market sale of 5,000 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 5,000 $23.53 $117.7K
Filing: Form 4 (Insider Transaction) Insider: Caine Paul (Director) Shares: 5,000 Est. Value: $117.7K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-11

MGNI insider Evans Katie Seitz (See Remarks) sold 13,997 shares (~$335.9K)

Evans Katie Seitz, listed as See Remarks at MAGNITE, INC., reported an open-market sale of 13,997 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 13,997 $24.00 $335.9K
Filing: Form 4 (Insider Transaction) Insider: Evans Katie Seitz (See Remarks) Shares: 13,997 Est. Value: $335.9K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-10

MGNI insider Evans Katie Seitz (See Remarks) sold 43,385 shares (~$1.02M)

Evans Katie Seitz, listed as See Remarks at MAGNITE, INC., reported an open-market sale of 43,385 MGNI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 13,546 $5.16 $69.9K
S Open-market sale 32,285 $23.63 $762.9K
S Open-market sale 11,100 $23.46 $260.4K
M Option exercise derivative · Employee Stock Option (Right to Buy) 13,546 — —
Filing: Form 4 (Insider Transaction) Insider: Evans Katie Seitz (See Remarks) Shares: 43,385 Est. Value: $1.02M
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 7 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. Magnite, Inc. has 7 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-09-17

MGNI Form 144 filed for proposed insider sale by PAUL CAINE (20,000 shares) ~$475.6K

PAUL CAINE filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: PAUL CAINE Shares: 20,000 Est. Value: $475.6K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-17

MGNI Form 144 filed for proposed insider sale by Douglas S. Knopper & Abigail L. Knopper TTEES of the Knopper Joint Mgmt Trust 11/15/13 (37,337 shares) ~$887.9K

Douglas S. Knopper & Abigail L. Knopper TTEES of the Knopper Joint Mgmt Trust 11/15/13 filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Douglas S. Knopper & Abigail L. Knopper TTEES of the Knopper Joint Mgmt Trust 11/15/13 Shares: 37,337 Est. Value: $887.9K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-14

MGNI Form 144 filed for proposed insider sale by ROBERT SPILLANE (10,363 shares) ~$246.2K

ROBERT SPILLANE filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: ROBERT SPILLANE Shares: 10,363 Est. Value: $246.2K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-14

MGNI Form 144 filed for proposed insider sale by DAVID BUONASERA (1,165 shares) ~$27.7K

DAVID BUONASERA filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: DAVID BUONASERA Shares: 1,165 Est. Value: $27.7K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-11

MGNI Form 144 filed for proposed insider sale by KATHERYN EVANS (13,997 shares) ~$335.9K

KATHERYN EVANS filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: KATHERYN EVANS Shares: 13,997 Est. Value: $335.9K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-10

MGNI Form 144 filed for proposed insider sale by PAUL CAINE (10,000 shares) ~$235.8K

PAUL CAINE filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: PAUL CAINE Shares: 10,000 Est. Value: $235.8K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-10

MGNI Form 144 filed for proposed insider sale by AARON SALTZ (60,000 shares) ~$1.41M

AARON SALTZ filed a Form 144 with the SEC indicating intent to sell MGNI (MAGNITE, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: AARON SALTZ Shares: 60,000 Est. Value: $1.41M
View on SEC EDGAR → Open Filing Document →
Material Events 2 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There are 2 in this period for Magnite, Inc. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-10-07

MGNI filed 8-K — material company event

MAGNITE, INC. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →
Form 8-K Material Company Update 2026-09-21

MGNI filed 8-K — material company event

MAGNITE, INC. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →

How we classify Magnite, Inc.'s filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on MGNI. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MGNI SEC Filings

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Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.
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