Ra Capital Management, L.P.
· New
Change
+1.9M
Date
Q1 2026
MG
| Investor | Type | Est. change | Change | Δ Own | Date | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Ra Capital Management, L.P.
· New
Change
+1.9M
Date
Q1 2026
|
Ra Capital Management, L.P. | New· Q1 2026 | – | +1.9M | – | Q1 2026 | |||||
|
Jefferies Financial Group Inc.
· Exited
Change
−1.8M
Δ Own
−100.0%
Date
Q1 2026
|
Jefferies Financial Group Inc. | Exited· Q1 2026 | – | −1.8M | −100.0% | Q1 2026 | |||||
|
Two Sigma Investments, LP
· Added
Change
+1.5M
Δ Own
+152.9%
Date
Q1 2026
|
Two Sigma Investments, LP | Added· Q1 2026 | – | +1.5M | +152.9% | Q1 2026 | |||||
|
Two Sigma Advisers, LP
· Exited
Change
−1.2M
Δ Own
−100.0%
Date
Q1 2026
|
Two Sigma Advisers, LP | Exited· Q1 2026 | – | −1.2M | −100.0% | Q1 2026 | |||||
|
Millennium Management LLC
· Added
Change
+820K
Date
Q1 2026
|
Millennium Management LLC | Added· Q1 2026 | – | +820K | – | Q1 2026 | |||||
|
Marshall Wace, LLP
· Added
Change
+741K
Date
Q1 2026
|
Marshall Wace, LLP | Added· Q1 2026 | – | +741K | – | Q1 2026 | |||||
|
Jane Street Group, LLC
· Reduced
Change
−646K
Date
Q1 2026
|
Jane Street Group, LLC | Reduced· Q1 2026 | – | −646K | – | Q1 2026 | |||||
|
Diadema Partners LP
· New
Change
+600K
Date
Q1 2026
|
Diadema Partners LP | New· Q1 2026 | – | +600K | – | Q1 2026 | |||||
|
Bank of America Corp
· Added
Change
+564K
Date
Q1 2026
|
Bank of America Corp | Added· Q1 2026 | – | +564K | – | Q1 2026 | |||||
|
Jacobs Levy Equity Management, Inc
· Reduced
Change
−460K
Date
Q1 2026
|
Jacobs Levy Equity Management, Inc | Reduced· Q1 2026 | – | −460K | – | Q1 2026 | |||||
|
Mackenzie Financial Corp
· Added
Change
+390K
Date
Q1 2026
|
Mackenzie Financial Corp | Added· Q1 2026 | – | +390K | – | Q1 2026 | |||||
|
Susquehanna International Group, LLP
· Added
Change
+384K
Date
Q1 2026
|
Susquehanna International Group, LLP | Added· Q1 2026 | – | +384K | – | Q1 2026 | |||||
|
Armistice Capital, LLC
· Reduced
Change
−312K
Date
Q1 2026
|
Armistice Capital, LLC | Reduced· Q1 2026 | – | −312K | – | Q1 2026 | |||||
|
Walleye Capital LLC
· Added
Change
+302K
Date
Q1 2026
|
Walleye Capital LLC | Added· Q1 2026 | – | +302K | – | Q1 2026 | |||||
|
D. E. Shaw & Co., Inc.
· Added
Change
+302K
Δ Own
+39.9%
Date
Q1 2026
|
D. E. Shaw & Co., Inc. | Added· Q1 2026 | – | +302K | +39.9% | Q1 2026 | |||||
| Insider | Title | Type | Price | Qty | Value | Owned | ΔOwn | Trade date | Filed date | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
O'Brien Federica F.
· Director
2 operations
26K
|
O'Brien Federica F. | Director | 2 operations | – | 26K | – | 4K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Jackson Scott Thomas
· Director
2 operations
26K
|
Jackson Scott Thomas | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Heiden William K.
· Director
2 operations
26K
|
Heiden William K. | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Liu Margaret
· Director
2 operations
26K
|
Liu Margaret | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Chhabra Meenu
· Director
2 operations
26K
|
Chhabra Meenu | Director | 2 operations | – | 26K | – | 4K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Hurwitz Edward
· Director
2 operations
26K
|
Hurwitz Edward | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Stump David C.
· Director
2 operations
26K
|
Stump David C. | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Ferrante Karen Jean
· Director
2 operations
26K
|
Ferrante Karen Jean | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
Koenig Scott
· Director
2 operations
26K
|
Koenig Scott | Director | 2 operations | – | 26K | – | 22K | – | May 19, 2026 | May 20, 2026 | |||||||||
|
O'Brien Federica F.
· Director
2 operations
0
|
O'Brien Federica F. | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
|
Jackson Scott Thomas
· Director
2 operations
0
|
Jackson Scott Thomas | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
|
Heiden William K.
· Director
2 operations
0
|
Heiden William K. | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
|
Siegel Jay Philip
· Director
2 operations
0
|
Siegel Jay Philip | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
|
Liu Margaret
· Director
2 operations
0
|
Liu Margaret | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
|
Chhabra Meenu
· Director
2 operations
0
|
Chhabra Meenu | Director | 2 operations | – | 0 | – | 0 | – | May 18, 2026 | May 20, 2026 | |||||||||
N
A
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95 reporting institutions disclosed MGNX position changes in the Q1 2026 snapshot.
For each manager, WhoBought compares accepted consecutive 13F share counts. Share change is current shares minus prior shares. Estimated dollar change is that signed share change multiplied by the split-adjusted quarter-mean close. The activity table on this page uses Q1 2026.
An investor crossing 5% of a share class generally files Schedule 13D for activist intent or Schedule 13G for a passive position. The technical form names appear here rather than in the activity rows.
Ownership and institutional activity come from SEC Form 13F filings. Insider activity comes from SEC Form 4, and large-shareholder activity from SEC Schedules 13D and 13G. FMP supplies price data only. Company logos use the local verified Parqet cache with one shared fallback.
Form 13F is a quarterly disclosure and is normally filed after the quarter ends. Every ownership and activity value therefore names its represented period; it is not presented as a live position.
A muted dash marks a missing table value. It means the filing omitted the value, comparable data is unavailable, or no prior position exists for comparison.