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MGNI · Magnite, Inc. · Holdings

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$24.00 +0.45 (+1.89%)
Market Cap
$3.38B
Shares
143.42M
Volume · Oct 20 585.09K Avg daily vol (3M) 2.37M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Institutional holdings are being reconciled with SEC filings. Holder totals and changes may be incomplete until reconciliation finishes.
The Sep 30, 2026 filing window is still open — showing the latest known positions. Funds that have not filed yet carry their prior-quarter positions; a fund that filed without this stock counts as sold out. Each fund's Change is measured against its own previous reported quarter, shown in the Reported column. Pick a completed quarter in the Quarter selector below to put every fund on one quarter and see the stock-wide activity breakdown.
Holders: 315
Total Value: $2,848,998,149
Total Shares: 149,787,415
Showing 1–100 of 333 holdings by value · page 1 of 4

Institutional Ownership Trend

27 quarters

Holder Concentration

Across 314 13F filers
Top Holder
8.5%
Sep 2023 → Jun 2026 · range 8.5% – 12.1%
of institutional value
Top 5
27.3%
Sep 2023 → Jun 2026 · range 27.3% – 39.7%
of institutional value
Top 10
42.4%
Sep 2023 → Jun 2026 · range 42.4% – 57.8%
of institutional value
HHI
274
Sep 2023 → Jun 2026 · range 274 – 467
Broadly held

Who Holds MGNI

Last 8 quarters through Sep 30, 2026 (filing window open)

Each kind of 13F filer's share of the common shares 13F filers report. Holder type comes from regulatory records, never the filer's name; style, turnover and horizon are measured from each filer's own 13F book. The quarter selector does not change this card.

Jun 30, 2026, the newest closed quarter: 311 filers, like-for-like change +7.8%; actively managed books +7.3%; index-like books +9.4%.

Holder type Share Filers Change
Registered adviser 51.4% 170 +4.2%
Exempt adviser 1.6% 4 +170.6%
Adviser 3.4% 7 -17.0%
Bank 6.9% 18 +20.3%
Insurer 0.4% 2 +11.4%
Broker-dealer 0.1% 1 -9.2%
Benefit plan 0.3% 3 +2.4%
Non-US 3.1% 9 +210.8%
Holding company 21.2% 9 +7.9%
Unknown 11.5% 88 0.0%

The Sep 30, 2026 filing window is still open, so its bar carries the Jun 30, 2026 positions of filers that have not filed yet.

How the mix is measured

Shares are 13F common shares restated to today's split basis; options and principal amounts are left out. The change compares only filers with a 13F in both quarters and keeps each filer in its bucket of the later quarter on both sides; a filer that continues under a new CIK is compared through its successor. Holder type comes from each filer's current regulatory profile; client base and private funds come from the Form ADV roster current at each quarter end (rosters from December 2019, so an earlier quarter reads Unknown). Style, turnover, horizon and book size are measured from each filer's 13F book in the newest measured quarter, and Not measured means none was. Actively managed books are those measured systematic-like, concentrated or diversified active.

Excluded 3 holders with no observed 2026-03-31 13F and 2 holders with no observed 2026-06-30 13F. Compared across CIK changes: 4 filers continue as Evelyn Partners Group Ltd; JANUS HENDERSON GROUP PLC continues as Jupiter Topco LLC.

Conviction and Crowding

311 13F filers, quarter ended Jun 30, 2026

Measured across every 13F filer's common-share book once the quarter's filing window closed. Crowding counts filers with high turnover or that advise private funds on Form ADV.

Conviction holders
11
3.54% of filers hold it in their top 10
Mar 31, 2026: 9
Holders above 5%
8
median weight 0.004%
Mar 31, 2026: 8
Crowding
36.4%
of shares outstanding, 89th percentile
Mar 31, 2026: 33.6%
Private-fund advisers
32.8%
of shares outstanding
Institutional ownership
99.1%
101.8% of the estimated free float above 100%: filers can report lent or client shares more than once
Top 10 holders
44.8%
of 13F shares, Herfindahl 0.030
Active holders
+7.3%
like-for-like share change of active filers
5% stakes on record
5
0 13D, 5 13G (5 institutional, 0 passive, 0 exempt)
How long holders have held it value-weighted 12.8 quarters
Under 1 year 19.7% 1 to 3 years 32.4% 3 years or more 47.9% Since coverage start 0.000%

Managers in the top fifth by current three-year FundScore alpha were net buyers of $13,216,539 (2 buying, 0 selling).

Estimated Holder Cost Basis

Quarter ended Jun 30, 2026, on that quarter's share basis

Estimated, never filed: each 13F buy is costed at its quarter's average traded price and each sale keeps the average cost, so this is what holders paid on average if they traded evenly through each quarter.

Estimated avg cost
$14.88
estimated per share
Mar 31, 2026: $15.03
Quarter-end price
$18.98
implied by 13F values
Estimated gain or loss
+27.5%
price against the estimated cost
Estimated at a loss
3.09%
of costed 13F value

Estimated cost covers 48.1% of the 13F shares; positions already held when a filer's 13F history starts, or bought in a quarter without a trusted average price, have no estimate.

Shared Holders

Companies MGNI's active holders also own, quarter ended Jun 30, 2026
# Company Shared holders
1 INDI indie Semiconductor, Inc. 7
2 BLZE Backblaze, Inc. 5
3 KRUS Kura Sushi USA, Inc. 5
4 APPS Digital Turbine, Inc. 5
5 AIOT Powerfleet, Inc. 6
6 TENB Tenable Holdings, Inc. 6
7 ASUR Asure Software Inc 4
8 OWLT Owlet, Inc. 3
9 SMWB Similarweb Ltd. 4
10 AMPL Amplitude, Inc. 4

Shareholder Targets

13F filers that own its peers but not MGNI, quarter ended Jun 30, 2026

Found through its holder-overlap peers: INDI, BLZE, KRUS, APPS, AIOT, TENB, ASUR, OWLT, SMWB, AMPL, DSP, LFCR, OPRX, GDYN, ARLO, PRCH, FIVN, MSEX, MEC, DRVN. 668 filers in all.

# Filer In peers
1 ARROWSTREET CAPITAL, LIMITED PARTNERSHIP Registered adviser, Diversified active $239,739,715 10 held
2 BAMCO INC /NY/ Registered adviser, Concentrated $183,132,783 3 held
3 PRIMECAP MANAGEMENT CO/CA/ Registered adviser, Diversified active $168,172,783 2 held
4 Driehaus Capital Management LLC Registered adviser, Diversified active $154,921,459 4 held
5 FIRST TRUST ADVISORS LP Registered adviser, Diversified active $154,534,192 4 held
6 BRANDES INVESTMENT PARTNERS, LP Registered adviser, Diversified active $144,959,227 1 held
7 T. Rowe Price Investment Management, Inc. Adviser, Diversified active $129,230,946 3 held
8 RENAISSANCE TECHNOLOGIES LLC Registered adviser, Diversified active $128,046,080 14 held
9 Portolan Capital Management, LLC Unknown, Diversified active $117,305,447 4 held
10 WASATCH ADVISORS LP Registered adviser, Diversified active $114,516,774 4 held

Fund Ownership of MGNI by Fund Type

Registered funds' Form N-PORT reports for the quarter ended Jun 30, 2026

Index funds and index ETFs hold 17.69% of shares outstanding.

Fund type Of shares outstanding Shares
Index funds 3.43% 4,914,385
Index ETFs 14.27% 20,461,819
Active ETFs 1.64% 2,356,409
Active funds 18.32% 26,275,061
Unclassified 0.60% 864,859
All registered funds 38.26% 54,872,533
How fund types are measured

Each fund series counts once, with its latest Form N-PORT report dated inside the quarter; only long share positions count, restated to today's split basis. The fund type is the series' latest Form N-CEN answer on or before the quarter end (the index-fund box and the exchange-traded flag), never its name. Unclassified funds have no usable N-CEN; unit investment trusts are among them, so index ownership is a floor. Funds sit inside their advisers' 13F reports, so these shares overlap the 13F figures and are never added to them.

Showing 100 of 333
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Holder Value (USD) % of 13F Shares Open

Showing the top 100 of 333 holders. Create a free account to see every holder, past quarters, search, filters and CSV export.

Key facts CIK 1595974 CUSIP 55955D100 13F (30d) 30 filings 29 filers Visit website Investor relations