Prothena Corp Public Ltd Co

PRTA

Exchange: Nasdaq
Industry: Pharmaceutical Preparations
SEC CIK: 0001559053

SEC filings (opens in a new tab)

In the last 90 days, Prothena Corp Public Ltd Co insiders filed 6 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.

Q1 2026 vs. Q4 2025

How the institutions holding Prothena Corp Public Ltd Co changed between Q4 2025 and Q1 2026.

All holders in Q1 2026 All holders in Q4 2025

13F holders of PRTA: Q4 2025 compared with Q1 2026
Measure	Q4 2025	Of which not filed for Q1 2026	Q1 2026	Change
Holders	182	3	186	+7
Shares	47.3M	2.14M	47.3M	+2.17M (+4.8%)
Value	$451.6M	$20.4M	$459.5M	+$28.4M (+6.6%)

3 institutions that held it in Q4 2025 haven't filed for Q1 2026 yet. Not filing isn't selling, so the changes leave them out.

New holders (30)

Institutions that held Prothena Corp Public Ltd Co at the end of Q1 2026 but not at the end of Q4 2025.

Institutions new to PRTA in Q1 2026
Institution	Shares	Value	% of portfolio
Vanguard Portfolio Management LLC	1,445,979	$14.1M	0.00%
Vanguard Capital Management LLC	484,126	$4.71M	0.00%
Deeter Investments LLP	300,000	$2.92M	0.51%
Penbrook Management LLC	271,720	$2.64M	2.00%
Vanguard Fiduciary Trust Co	254,573	$2.47M	0.00%
Jackson Creek Investment Advisors LLC	54,089	$526.0K	0.15%
Winton Group Ltd	34,700	$337.3K	0.01%
Cornerstone Investment Partners, LLC	30,687	$298.3K	0.01%
Foundation Wealth Management, LLC	19,236	$187.0K	0.13%
Vanguard Global Advisers, LLC	18,249	$177.4K	0.00%
SEI Investments Co	17,248	$167.6K	0.00%
Chicago Trust Co NA	15,057	$146.4K	0.02%
Mercer Global Advisors Inc	13,094	$127.3K	0.00%
Schonfeld Strategic Advisors LLC	12,399	$120.5K	0.00%
Commonwealth Equity Services, LLC	11,930	$116.0K	0.00%
JBF Capital, Inc.	10,285	$100.0K	0.01%
Savant Capital, LLC	10,131	$98.5K	0.00%
Prudential Financial Inc	10,025	$97.4K	0.00%
Vontobel Holding Ltd.	10,000	$97.2K	0.00%
Cresset Asset Management, LLC	10,000	$97.2K	0.00%
Group One Trading, L.P.	3,416	$33.2K	0.00%
Aster Capital Management (DIFC) Ltd	256	$3.17K	0.00%
UBS Asset Management Americas Inc	131	$1.27K	0.00%
CVA Family Office, LLC	109	$1.06K	0.00%
Keating Financial Advisory Services, Inc.	76	$739	0.00%
Cornerstone Financial Management LLC	55	$535	0.00%
Root Financial Partners, LLC	38	$369	0.00%
Advisory Services Network, LLC	30	$292	0.00%
Leo H. Evart, Inc.	22	$214	0.00%
Wealth Preservation Advisors, LLC	1	$10	0.00%

Sold out (23)

Institutions that held Prothena Corp Public Ltd Co at the end of Q4 2025 and filed for Q1 2026 without it.

Institutions that sold out of PRTA in Q1 2026
Institution	Shares, Q4 2025	Value, Q4 2025
Two Sigma Advisers, LP	427,400	$4.08M
Arrowstreet Capital, Limited Partnership	298,101	$2.85M
Diadema Partners LP	106,539	$1.02M
Caption Management, LLC	61,009	$582.6K
Franklin Resources Inc	47,251	$451.2K
DekaBank Deutsche Girozentrale	14,000	$383.0K
Quadrature Capital Ltd	31,090	$296.9K
Persistent Asset Partners Ltd	28,589	$273.0K
Polymer Capital Management (US) LLC	23,513	$224.5K
Headlands Technologies LLC	23,352	$223.0K
Millennium Management LLC	21,976	$209.9K
Atom Investors LP	17,026	$162.6K
Entropy Technologies, LP	16,900	$161.4K
DRW Securities, LLC	11,955	$114.2K
PDT Partners, LLC	11,334	$108.2K
ProShare Advisors LLC	10,425	$99.6K
Canada Pension Plan Investment Board	7,100	$67.8K
Flagship Wealth Advisors, LLC	1,500	$14.3K
Amalgamated Bank	1,383	$13.0K
Torren Management, LLC	884	$8.44K
Daiwa Securities Group Inc.	195	$2.00K
Zurcher Kantonalbank (Zurich Cantonalbank)	71	$678
Resources Management Corp	3	$0

Not filed for Q1 2026 yet (3)

Institutions that held Prothena Corp Public Ltd Co at the end of Q4 2025 and haven't filed a 13F for Q1 2026. Not filing isn't selling, so they aren't counted as sold out.

Institutions holding PRTA in Q4 2025 that haven't filed for Q1 2026
Institution	Shares, Q4 2025	Value, Q4 2025
Vanguard Group Inc	2,140,909	$20.4M
CIBC Private Wealth Group, LLC	48	$458
New Millennium Group LLC	1	$10