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Prothena Corp Public Ltd Co

PRTA
Exchange
Nasdaq
Industry
Pharmaceutical Preparations
SEC CIK
0001559053

In the last 90 days, Prothena Corp Public Ltd Co insiders filed 4 open-market purchases and 2 sales; 187 institutions reported holding it in 13F filings for Q2 2026, worth $462.7M in total; no superinvestor holds it.

Holders of 5% or more of PRTA

Holders whose latest Schedule 13D or 13G filing reports 5% or more of Prothena Corp Public Ltd Co, largest stake first. The change is against the holder's previous filing.

Holders of 5% or more of PRTA
HolderLatest formStakeChangeFirst filedLatest filingFiling
Scully William P13G/A9.80%5.28M shares−0.10 ppfrom 9.90%Feb 21, 20254 filingsNov 12, 2025SEC
Fennell Todd W.13G/A8.40%4.50M shares+0.30 ppfrom 8.10%Feb 14, 20254 filingsNov 12, 2025SEC
Rubric Capital Management LP13G6.83%3.68M sharesNewFeb 13, 20261 filingFeb 13, 2026SEC
BlackRock, Inc.13G/A5.70%3.09M shares–Oct 17, 20251 filingOct 17, 2025SEC

Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.

13D and 13G filings

20 Schedule 13D and 13G filings on Prothena Corp Public Ltd Co, newest first, including old-format filings without a stake.

Schedule 13D and 13G filings on PRTA
Filed (ET)FilerFormStakeChangeEvent dateFiling
Feb 13, 20264:16 PM ETRubric Capital Management LPand 1 other13G6.83%3.68M sharesNewDec 31, 2025SEC
Nov 14, 20257:47 PM ETADAR1 Capital Management, LLCand 2 others13G/A2.70%1.47M shares−3.60 ppfrom 6.30%Below 5%Sep 30, 2025SEC
Nov 12, 20253:51 PM ETFennell Todd W.13G/A8.40%4.50M shares+0.30 ppfrom 8.10%Sep 30, 2025SEC
Nov 12, 20253:47 PM ETScully William P13G/A9.80%5.28M shares−0.10 ppfrom 9.90%Sep 30, 2025SEC
Oct 17, 20254:07 PM ETBlackRock, Inc.13G/A5.70%3.09M shares–Sep 30, 2025SEC
Aug 14, 20258:17 PM ETADAR1 Capital Management, LLCand 2 others13G6.30%3.38M sharesNewJun 30, 2025SEC
Aug 14, 20251:16 PM ETLogos Global Management LPand 4 others13G/A0.00%0 shares−5.50 ppfrom 5.50%Below 5%Jun 30, 2025SEC
Aug 14, 20251:07 PM ETPrice T Rowe Associates Inc13G/A0.10%71.0K shares–Below 5%Jun 30, 2025SEC
Aug 13, 20254:14 PM ETScully William P13G/A9.90%5.35M shares−0.50 ppfrom 10.40%Jun 30, 2025SEC
Aug 13, 20254:00 PM ETFennell Todd W.13G/A8.10%4.35M shares−0.40 ppfrom 8.50%Jun 30, 2025SEC
Jun 5, 20257:43 PM ETWellington Management Group LLPand 2 others13G/A0.20%108.2K shares−9.30 ppfrom 9.50%Below 5%May 30, 2025SEC
Jun 4, 20255:18 PM ETLogos Global Management LPand 4 others13G5.50%2.95M sharesNewMay 29, 2025SEC
May 29, 20259:08 PM ETEcoR1 Capital, LLCand 2 others13D/A0.00%0 shares−9.90 ppfrom 9.90%Below 5%May 27, 2025SEC
May 15, 202510:00 AM ETFennell Todd W.13G/A8.50%4.59M shares−0.10 ppfrom 8.60%Mar 31, 2025SEC
May 14, 202510:34 AM ETScully William P13G/A10.40%5.61M shares+0.10 ppfrom 10.30%Mar 31, 2025SEC
May 6, 20257:08 PM ETEcoR1 Capital, LLCand 2 others13D/A9.90%5.30M shares−11.60 ppfrom 21.50%May 2, 2025SEC
Feb 21, 20252:49 PM ETScully William P13G/A10.30%5.56M shares–Dec 31, 2024SEC
Feb 14, 20253:35 PM ETFennell Todd W.13G/A8.60%4.65M shares–Dec 31, 2024SEC
Feb 10, 202510:25 AM ETWellington Management Group LLPand 3 others13G/A9.50%5.13M shares–Dec 31, 2024SEC
Jan 3, 20257:45 PM ETEcoR1 Capital, LLCand 2 others13D/A21.50%11.6M shares–Dec 31, 2024SEC

Form 144: proposed insider sales

Notices from officers, directors and other affiliates planning to sell Prothena Corp Public Ltd Co shares.

No Form 144 notices for Prothena Corp Public Ltd Co are on file.