Magnite, Inc.
MX ˙ BMV ˙ US55955D1000
SecurityMX:MGNI / Magnite, Inc.
InstitutionIMC-Chicago, LLC
Latest Disclosed Ownership27,774 shares
Latest Disclosed Value $ 329,955
IMC-Chicago, LLC ownership in MGNI / Magnite, Inc.

On May 5, 2026 - IMC-Chicago, LLC filed a 13F-HR form disclosing ownership of 27,774 shares of Magnite, Inc. (MX:MGNI) valued at $329,955 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 29, 2026 disclosing 133,096 shares of Magnite, Inc.. This represents a change in shares of -79.13% during the quarter.

IMC-Chicago, LLC has a history of taking positions in derivatives of the underlying security (MGNI) in the form of stock options. The firm currently holds call options representing 124,700 of underlying shares valued at $1,481,436 USD and put options representing 99,600 of underlying shares valued at $1,183,248 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

MX:MGNI / Magnite, Inc. Historical Put/Call Ratio
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)
2026-05-05 2026-03-31 13F MAGNITE COM 55955D100 27,774 -105,322 -79.13 330 -84.77 0.0001
2026-01-29 2025-12-31 13F MAGNITE COM 55955D100 133,096 133,096 2,160 0.0008
2025-07-22 2025-06-30 13F MAGNITE COM 55955D100 0 -39,631 -100.00 0 -100.00
2025-04-14 2025-03-31 13F MAGNITE COM 55955D100 39,631 -36,779 -48.13 452 -62.83 0.0003
2025-01-27 2024-12-31 13F MAGNITE COM 55955D100 76,410 2,317 3.13 1,216 18.52 0.0006
2024-10-25 2024-09-30 13F MAGNITE COM 55955D100 74,093 -11,943 -13.88 1,026 -10.24 0.0006
2024-07-15 2024-06-30 13F MAGNITE COM 55955D100 86,036 58,715 214.91 1,143 290.10 0.0007
2024-04-12 2024-03-31 13F MAGNITE COM 55955D100 27,321 -2,950 -9.75 294 3.90 0.0002
2024-02-09 2023-12-31 13F MAGNITE COM 55955D100 30,271 3,118 11.48 283 38.24 0.0002
2023-10-12 2023-09-30 13F MAGNITE COM 55955D100 27,153 27,153 205 0.0002
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-05 2026-03-31 13F MAGNITE COM Call 124,700 -66.84 1,481 -75.73 n/a n/a n/a
2026-01-29 2025-12-31 13F MAGNITE COM Call 376,000 -9.79 6,102 -32.78 n/a n/a n/a
2025-11-04 2025-09-30 13F MAGNITE COM Call 416,800 27.89 9,078 15.48 n/a n/a n/a
2025-07-22 2025-06-30 13F MAGNITE COM Call 325,900 151.66 7,861 432.16 n/a n/a n/a
2025-04-14 2025-03-31 13F MAGNITE COM Call 129,500 -22.32 1,478 -44.33 n/a n/a n/a
2025-01-27 2024-12-31 13F MAGNITE COM Call 166,700 -1.13 2,654 13.62 n/a n/a n/a
2024-10-25 2024-09-30 13F MAGNITE COM Call 168,600 1.14 2,335 5.42 n/a n/a n/a
2024-07-15 2024-06-30 13F MAGNITE COM Call 166,700 186.43 2,215 254.40 n/a n/a n/a
2024-04-12 2024-03-31 13F MAGNITE COM Call 58,200 19.75 626 37.97 n/a n/a n/a
2024-02-09 2023-12-31 13F MAGNITE COM Call 48,600 -0.61 454 23.10 n/a n/a n/a
2023-10-12 2023-09-30 13F MAGNITE COM Call 48,900 369 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-05 2026-03-31 13F MAGNITE COM Put 99,600 -20.45 1,183 -41.75 n/a n/a n/a
2026-01-29 2025-12-31 13F MAGNITE COM Put 125,200 10.70 2,032 -17.54 n/a n/a n/a
2025-11-04 2025-09-30 13F MAGNITE COM Put 113,100 41.02 2,463 27.35 n/a n/a n/a
2025-07-22 2025-06-30 13F MAGNITE COM Put 80,200 -27.88 1,934 52.52 n/a n/a n/a
2025-04-14 2025-03-31 13F MAGNITE COM Put 111,200 -19.77 1,269 -42.52 n/a n/a n/a
2025-01-27 2024-12-31 13F MAGNITE COM Put 138,600 49.03 2,207 71.27 n/a n/a n/a
2024-10-25 2024-09-30 13F MAGNITE COM Put 93,000 9.03 1,288 13.68 n/a n/a n/a
2024-07-15 2024-06-30 13F MAGNITE COM Put 85,300 196.18 1,134 266.67 n/a n/a n/a
2024-04-12 2024-03-31 13F MAGNITE COM Put 28,800 5.11 310 21.18 n/a n/a n/a
2024-02-09 2023-12-31 13F MAGNITE COM Put 27,400 -19.65 256 -0.78 n/a n/a n/a
2023-10-12 2023-09-30 13F MAGNITE COM Put 34,100 257 n/a n/a n/a
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.