PRTA · Prothena Corp Public Ltd Co · Shareholders & Ownership

$8.50 +0.02 (+0.24%) At close · Oct 20

Russell 2000 member Rebalance outlook locked

Market Cap

$436.36M

51.34M

Volume · Oct 20 529.08K Avg daily vol (3M) 486.3K

Every disclosed holder of PRTA in one list: 13F institutions, Schedule 13D and 13G filers, insiders (Forms 3, 4 and 5) and registered funds, each from its own latest filing. Holders nest by CIK and SEC reporting links, never by name, and each is summed once.

How the holder list picks a filing →

Who Owns PRTA

13F quarter Sep 30, 2026, combined view: filers that have not filed yet carry their Jun 30, 2026 positions

No chart: the summed disclosures exceed shares outstanding, so they are not parts of one whole.

Holder group	Holders	Shares	% Out	Summed
Institutional (13F)	186	47,200,785	91.94%	Yes
Insiders (Forms 3, 4, 5)	11	7,474,854	14.56%	Yes
13D/G-only blocks	2	5,357,054	10.44%	Yes
Remaining	—	8,695,719	-16.94%	Negative
Registered funds (N-PORT, not summed)	55	3,111,984	6.06%	No

Shares outstanding: 51,336,974, the issuer's latest cover-page count restated onto today's split basis.

Remaining is negative: the summed disclosures exceed shares outstanding, as when filings are dated at different times or holders that do not disclose their links count the same shares. It is flagged, not clipped.

13D/G-only counts each filer's latest 13D or 13G that no 13F report of the listing contains, that names no 13F filer and that no counted insider files. Funds are never summed: their shares sit inside their advisers' 13F reports.

Holders of PRTA

One row per holder Every filing By ultimate parent

All 13F Funds Insiders 13D/G Non-US

#	Holder	Shares	% Out	Change	As of	Notes
1	FMR LLC 13F CIK 315066 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	7,199,218	14.02%	-352,000	Jun 30, 2026	carried, not yet filed for the newest quarter
1.1	FMR LLC 13G CIK 315066 · Holding company · Jun 30, 2026 Rule 13d-1(b), qualified institution, not summed	7,199,218	14.02%	—	Jun 30, 2026	Rule 13d-1(b), qualified institution, not summed
2	Fennell Todd W. 13G CIK 2011420 · Unknown · Aug 18, 2026 Rule 13d-1(c), passive investor	5,248,846	10.22%	+238,000	Aug 18, 2026	Rule 13d-1(c), passive investor
3	Rubric Capital Management LP 13F CIK 1687509 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	5,000,000	9.74%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
4	BlackRock, Inc. 13F CIK 2012383 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	4,867,955	9.48%	+223,795	Jun 30, 2026	carried, not yet filed for the newest quarter
4.1	BlackRock, Inc. 13G CIK 2012383 · Holding company · Jun 30, 2026 Rule 13d-1(b), qualified institution, not summed	3,587,480	6.99%	+495,219	Jun 30, 2026	Rule 13d-1(b), qualified institution, not summed
4.2	iShares Neuroscience and Healthcare ETF Fund S000076483 · Registered fund · Jul 31, 2026 iShares Trust, not summed	2,759	0.01%	+367	Jul 31, 2026	iShares Trust, not summed
5	STATE STREET CORP 13F CIK 93751 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	2,393,424	4.66%	+454,926	Jun 30, 2026	carried, not yet filed for the newest quarter
6	ACADIAN ASSET MANAGEMENT LLC 13F CIK 916542 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	2,010,645	3.92%	+463,052	Jun 30, 2026	carried, not yet filed for the newest quarter
7	SCULLY WILLIAM P Insider CIK 1045463 · Oct 14, 2026 10% Owner, issuer-wide	1,753,000	3.41%	+110,000	Oct 14, 2026	10% Owner, issuer-wide
7.1	SCULLY WILLIAM P 13G CIK 1045463 · Unknown · May 7, 2026 Rule 13d-1(c), passive investor, not summed	5,378,846	10.48%	+97,000	May 7, 2026	Rule 13d-1(c), passive investor, not summed
8	VANGUARD PORTFOLIO MANAGEMENT LLC 13F CIK 2100121 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,651,293	3.22%	+205,314	Jun 30, 2026	carried, not yet filed for the newest quarter
9	D. E. Shaw & Co., Inc. 13F CIK 1009207 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	1,611,457	3.14%	-151,890	Jun 30, 2026	carried, not yet filed for the newest quarter
10	ADAR1 Capital Management, LLC 13F CIK 1940272 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,554,535	3.03%	-26,908	Jun 30, 2026	carried, not yet filed for the newest quarter
11	TWO SIGMA INVESTMENTS, LP 13F CIK 1179392 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,264,987	2.46%	+59,009	Jun 30, 2026	carried, not yet filed for the newest quarter
12	Palo Alto Investors LP 13F CIK 1306923 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,143,155	2.23%	-65,413	Jun 30, 2026	carried, not yet filed for the newest quarter
13	GEODE CAPITAL MANAGEMENT, LLC 13F CIK 1214717 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,125,877	2.19%	+27,711	Jun 30, 2026	carried, not yet filed for the newest quarter
14	FEDERATED HERMES, INC. 13F CIK 1056288 · Investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,084,401	2.11%	+24,552	Jun 30, 2026	carried, not yet filed for the newest quarter
15	MORGAN STANLEY 13F CIK 895421 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	995,348	1.94%	-235,100	Jun 30, 2026	carried, not yet filed for the newest quarter
16	GOLDMAN SACHS GROUP INC 13F CIK 886982 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	979,730	1.91%	+160,845	Jun 30, 2026	carried, not yet filed for the newest quarter
17	JACOBS LEVY EQUITY MANAGEMENT, INC 13F CIK 884414 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	965,988	1.88%	-6,029	Jun 30, 2026	carried, not yet filed for the newest quarter
18	DIMENSIONAL FUND ADVISORS LP 13F CIK 354204 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	905,651	1.76%	+123,048	Jun 30, 2026	carried, not yet filed for the newest quarter
18.1	Dimensional U.S. Small Cap ETF Fund S000070906 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	120,757	0.24%	-56,566	Jul 31, 2026	Dimensional ETF Trust, not summed
18.2	Dimensional U.S. Core Equity 2 ETF Fund S000070903 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	71,109	0.14%	+57,984	Jul 31, 2026	Dimensional ETF Trust, not summed
18.3	Dimensional US Core Equity Market ETF Fund S000069432 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	16,113	0.03%	-2,500	Jul 31, 2026	Dimensional ETF Trust, not summed
18.4	Dimensional U.S. Equity Market ETF Fund S000070902 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	10,778	0.02%	+3,828	Jul 31, 2026	Dimensional ETF Trust, not summed
18.5	Dimensional US Core Equity 1 ETF Fund S000081780 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	5,606	0.01%	0	Jul 31, 2026	Dimensional ETF Trust, not summed
19	Qube Research & Technologies Ltd 13F CIK 1729829 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	791,169	1.54%	+176,566	Jun 30, 2026	carried, not yet filed for the newest quarter
20	VANGUARD EXPLORER FUND Fund S000002578 · Registered fund · Jul 31, 2026 VANGUARD EXPLORER FUND, not summed	757,200	1.48%	+139,978	Jul 31, 2026	VANGUARD EXPLORER FUND, not summed
21	RENAISSANCE TECHNOLOGIES LLC 13F CIK 1037389 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	697,615	1.36%	+90,100	Jun 30, 2026	carried, not yet filed for the newest quarter
22	Man Group plc 13F CIK 1637460 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	678,116	1.32%	+296,542	Jun 30, 2026	carried, not yet filed for the newest quarter
23	Mariner, LLC 13F CIK 1373442 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	625,095	1.22%	+62,013	Jun 30, 2026	carried, not yet filed for the newest quarter
24	Nuveen, LLC 13F CIK 1871926 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	557,157	1.09%	-202,211	Jun 30, 2026	carried, not yet filed for the newest quarter
24.1	Nuveen Small Cap Blend Index Fund Fund S000005367 · Registered fund · Jul 31, 2026 TIAA-CREF Funds, not summed	56,664	0.11%	0	Jul 31, 2026	TIAA-CREF Funds, not summed
24.2	Nuveen Equity Index Fund Fund S000005360 · Registered fund · Jul 31, 2026 TIAA-CREF Funds, not summed	31,537	0.06%	0	Jul 31, 2026	TIAA-CREF Funds, not summed
24.3	Nuveen Life Small Cap Equity Fund Fund S000005093 · Registered fund · Jun 30, 2026 TIAA-CREF Life Funds, not summed	9,200	0.02%	-4,429	Jun 30, 2026	TIAA-CREF Life Funds, not summed
24.4	TIAA Separate Account VA-1 - Stock Index Account Fund S000005098 · Registered fund · Jun 30, 2026 TIAA Separate Account VA-1, not summed	1,011	0.00%	0	Jun 30, 2026	TIAA Separate Account VA-1, not summed
24.5	Nuveen Life Stock Index Fund Fund S000005094 · Registered fund · Jun 30, 2026 TIAA-CREF Life Funds, not summed	672	0.00%	0	Jun 30, 2026	TIAA-CREF Life Funds, not summed
25	VANGUARD EXTENDED MARKET INDEX FUND Fund S000002841 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	480,189	0.94%	-3,469	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
26	VANGUARD CAPITAL MANAGEMENT LLC 13F CIK 2100119 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	479,945	0.93%	-4,181	Jun 30, 2026	carried, not yet filed for the newest quarter
27	NORTHERN TRUST CORP 13F CIK 73124 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	457,124	0.89%	+87,582	Jun 30, 2026	carried, not yet filed for the newest quarter
27.1	Small Cap Value Fund Fund S000001246 · Registered fund · Jun 30, 2026 Northern Funds, not summed	60,985	0.12%	—	Jun 30, 2026	Northern Funds, not summed
27.2	Small Cap Index Fund Fund S000001245 · Registered fund · Jun 30, 2026 Northern Funds, not summed	23,024	0.04%	+1,204	Jun 30, 2026	Northern Funds, not summed
27.3	Small Cap Core Fund Fund S000001244 · Registered fund · Jun 30, 2026 Northern Funds, not summed	3,644	0.01%	-173	Jun 30, 2026	Northern Funds, not summed
28	Birchview Capital, LP 13F CIK 1618205 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	449,019	0.87%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
29	Rangeley Capital, LLC 13F CIK 1517796 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	417,270	0.81%	-32,190	Jun 30, 2026	carried, not yet filed for the newest quarter
30	CHARLES SCHWAB INVESTMENT MANAGEMENT INC 13F CIK 884546 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	355,896	0.69%	-769	Jun 30, 2026	carried, not yet filed for the newest quarter
31	CITADEL ADVISORS LLC 13F CIK 1423053 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	338,810	0.66%	-96,764	Jun 30, 2026	carried, not yet filed for the newest quarter
32	VANGUARD STRATEGIC SMALL-CAP EQUITY FUND Fund S000012432 · Registered fund · Jun 30, 2026 VANGUARD HORIZON FUNDS, not summed	333,148	0.65%	0	Jun 30, 2026	VANGUARD HORIZON FUNDS, not summed
33	MONIMUS CAPITAL MANAGEMENT, LP 13F CIK 1848831 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	329,052	0.64%	-156,565	Jun 30, 2026	carried, not yet filed for the newest quarter
34	BNP PARIBAS ARBITRAGE, SA 13F CIK 1166588 · Non-US institution · Jun 30, 2026 carried, not yet filed for the newest quarter	315,803	0.62%	-108,793	Jun 30, 2026	carried, not yet filed for the newest quarter
35	AQR CAPITAL MANAGEMENT LLC 13F CIK 1167557 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	302,572	0.59%	+98,556	Jun 30, 2026	carried, not yet filed for the newest quarter
36	Penbrook Management LLC 13F CIK 1381055 · Registered investment adviser · Sep 30, 2026	271,720	0.53%	0	Sep 30, 2026
37	VANGUARD FIDUCIARY TRUST CO 13F CIK 933478 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	259,064	0.50%	+4,491	Jun 30, 2026	carried, not yet filed for the newest quarter
38	UBS Group AG 13F CIK 1610520 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	241,425	0.47%	-87,066	Jun 30, 2026	carried, not yet filed for the newest quarter
39	MACKENZIE FINANCIAL CORP 13F CIK 919859 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	239,899	0.47%	+239,899	Jun 30, 2026	carried, not yet filed for the newest quarter
40	VANGUARD RUSSELL 2000 INDEX FUND Fund S000030003 · Registered fund · May 31, 2026 VANGUARD SCOTTSDALE FUNDS, not summed	225,531	0.44%	+7,081	May 31, 2026	VANGUARD SCOTTSDALE FUNDS, not summed
41	Squarepoint Ops LLC 13F CIK 1642575 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	223,971	0.44%	-6,949	Jun 30, 2026	carried, not yet filed for the newest quarter
42	BANK OF AMERICA CORP /DE/ 13F CIK 70858 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	208,246	0.41%	-185,386	Jun 30, 2026	carried, not yet filed for the newest quarter
43	Focused Wealth Management, Inc 13F CIK 1586052 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	207,445	0.40%	+42	Jun 30, 2026	carried, not yet filed for the newest quarter
44	Bridge Builder Small/Mid Cap Growth Fund Fund S000048336 · Registered fund · Jun 30, 2026 Bridge Builder Trust, not summed	200,072	0.39%	-1,551	Jun 30, 2026	Bridge Builder Trust, not summed
45	Connor, Clark & Lunn Investment Management Ltd. 13F CIK 1596800 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	191,693	0.37%	+35,142	Jun 30, 2026	carried, not yet filed for the newest quarter
46	MARSHALL WACE, LLP 13F CIK 1318757 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	190,834	0.37%	+146,260	Jun 30, 2026	carried, not yet filed for the newest quarter
47	Quantinno Capital Management LP 13F CIK 1759654 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	158,331	0.31%	+14,032	Jun 30, 2026	carried, not yet filed for the newest quarter
48	DIADEMA PARTNERS LP 13F CIK 2026172 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	149,482	0.29%	+149,482	Jun 30, 2026	carried, not yet filed for the newest quarter
49	VANGUARD HEALTH CARE INDEX FUND Fund S000004450 · Registered fund · May 31, 2026 VANGUARD WORLD FUND, not summed	136,559	0.27%	-1,151	May 31, 2026	VANGUARD WORLD FUND, not summed
50	Bank of New York Mellon Corp 13F CIK 1390777 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	133,906	0.26%	-2,416	Jun 30, 2026	carried, not yet filed for the newest quarter

2 more nested rows are not shown here; Every filing lists them all.

Shares are restated onto today's split basis. Change compares each row with the same holder's previous filing in the same source; a dash means there is none to compare. Nested 13D/G, insider and fund rows are not summed, since a 13F report already holds them.

Showing 1–50 of 223 holders

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Key facts CIK 1559053 CUSIP G72800108 13F (30d) 18 filings 18 filers Visit website Investor relations