偉大的公司
MX ˙ BMV ˙ US55955D1000
SecurityMX:MGNI / Magnite, Inc.
InstitutionSei Investments Co
Latest Disclosed Ownership211,537 shares
Latest Disclosed Value $ 3,433,249
Sei Investments Co reports 182.11% increase in ownership of MGNI / Magnite, Inc.

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 211,537 shares of Magnite, Inc. (MX:MGNI) valued at $3,433,249 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 74,983 shares of Magnite, Inc.. This represents a change in shares of 182.11% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-02-13 2025-12-31 13F MAGNITE COM 55955D100 211,537 136,554 182.11 3,433 110.23 0.0034
2025-11-13 2025-09-30 13F MAGNITE COM 55955D100 74,983 -7,133 -8.69 1,633 -17.53 0.0018
2025-08-14 2025-06-30 13F MAGNITE COM 55955D100 82,116 42,353 106.51 1,981 337.09 0.0023
2025-05-14 2025-03-31 13F/A-1 MAGNITE COM 55955D100 39,763 -6,406 -13.88 454 -38.37 0.0006
2025-05-13 2025-03-31 13F MAGNITE COM 55955D100 46,169 0 735 0.0008
2025-02-11 2024-12-31 13F MAGNITE COM 55955D100 46,169 21,464 86.88 735 114.91 0.0009
2024-11-12 2024-09-30 13F MAGNITE COM 55955D100 24,705 24,705 342 0.0004
2023-11-14 2023-09-30 13F MAGNITE COM 55955D100 0 -27,466 -100.00 0 -100.00
2023-08-11 2023-06-30 13F MAGNITE COM 55955D100 27,466 6,367 30.18 375 91.79 0.0007
2023-05-12 2023-03-31 13F MAGNITE COM 55955D100 21,099 9,010 74.53 195 52.34 0.0004
2023-02-10 2022-12-31 13F MAGNITE COM 55955D100 12,089 12,089 128 0.0003
2022-11-14 2022-09-30 13F MAGNITE COM 55955D100 0 -42,681 -100.00 0 -100.00
2022-08-15 2022-06-30 13F MAGNITE COM 55955D100 42,681 42,681 379 0.0008
2022-02-14 2021-12-31 13F MAGNITE COM 55955D100 0 -22,696 -100.00 0 -100.00
2021-11-12 2021-09-30 13F MAGNITE COM 55955D100 22,696 -101,839 -81.78 633 -84.98 0.0013
2021-08-06 2021-06-30 13F MAGNITE COM 55955D100 124,535 52,636 73.21 4,215 40.88 0.0093
2021-05-12 2021-03-31 13F MAGNITE COM 55955D100 71,899 71,899 2,992 0.0075
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.