FMR LLC
· Reduced
Change
−601K
Δ Own
−10.8%
Date
Q1 2026
AR
| Investor | Type | Est. change | Change | Δ Own | Date | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
FMR LLC
· Reduced
Change
−601K
Δ Own
−10.8%
Date
Q1 2026
|
FMR LLC | Reduced· Q1 2026 | – | −601K | −10.8% | Q1 2026 | |||||
|
Wellington Management Group LLP
· Added
Change
+342K
Δ Own
+50.4%
Date
Q1 2026
|
Wellington Management Group LLP | Added· Q1 2026 | – | +342K | +50.4% | Q1 2026 | |||||
|
Capital World Investors
· Added
Change
+340K
Date
Q1 2026
|
Capital World Investors | Added· Q1 2026 | – | +340K | – | Q1 2026 | |||||
|
Artisan Partners Limited Partnership
· Reduced
Change
−289K
Date
Q1 2026
|
Artisan Partners Limited Partnership | Reduced· Q1 2026 | – | −289K | – | Q1 2026 | |||||
|
Clearbridge Investments, LLC
· Reduced
Change
−282K
Date
Q1 2026
|
Clearbridge Investments, LLC | Reduced· Q1 2026 | – | −282K | – | Q1 2026 | |||||
|
Invesco Ltd.
· Added
Change
+178K
Δ Own
+42.8%
Date
Q1 2026
|
Invesco Ltd. | Added· Q1 2026 | – | +178K | +42.8% | Q1 2026 | |||||
|
Voya Investment Management LLC
· Reduced
Change
−164K
Date
Q1 2026
|
Voya Investment Management LLC | Reduced· Q1 2026 | – | −164K | – | Q1 2026 | |||||
|
Two Sigma Investments, LP
· Reduced
Change
−149K
Δ Own
−57.8%
Date
Q1 2026
|
Two Sigma Investments, LP | Reduced· Q1 2026 | – | −149K | −57.8% | Q1 2026 | |||||
|
Bellevue Group AG
· Reduced
Change
−149K
Date
Q1 2026
|
Bellevue Group AG | Reduced· Q1 2026 | – | −149K | – | Q1 2026 | |||||
|
Two Sigma Advisers, LP
· Exited
Change
−136K
Δ Own
−100.0%
Date
Q1 2026
|
Two Sigma Advisers, LP | Exited· Q1 2026 | – | −136K | −100.0% | Q1 2026 | |||||
|
Citadel Advisors LLC
· Reduced
Change
−132K
Δ Own
−37.5%
Date
Q1 2026
|
Citadel Advisors LLC | Reduced· Q1 2026 | – | −132K | −37.5% | Q1 2026 | |||||
|
Acadian Asset Management LLC
· Exited
Change
−118K
Δ Own
−100.0%
Date
Q1 2026
|
Acadian Asset Management LLC | Exited· Q1 2026 | – | −118K | −100.0% | Q1 2026 | |||||
|
BNP Paribas Financial Markets
· Added
Change
+107K
Date
Q1 2026
|
BNP Paribas Financial Markets | Added· Q1 2026 | – | +107K | – | Q1 2026 | |||||
|
Adage Capital Partners Gp, L.L.C.
· New
Change
+90K
Date
Q1 2026
|
Adage Capital Partners Gp, L.L.C. | New· Q1 2026 | – | +90K | – | Q1 2026 | |||||
|
Janus Henderson Group PLC
· Added
Change
+84K
Date
Q1 2026
|
Janus Henderson Group PLC | Added· Q1 2026 | – | +84K | – | Q1 2026 | |||||
N
M
G
A
A
M
494 reporting institutions disclosed ARGX 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.