PRTA Insider Trading

Insider Trading Chart
Insider Trading History
Frequently Asked Questions
About

Insider Ownership Percentage: 10.00%

Insider Buying (Last 12 Months): $2,750,103.48

Insider Selling (Last 12 Months): $0.00

Prothena Insider Trading History Chart

Prothena Share Price & Price History

^$11.16

▼ -0.01 (-0.09%)

As of 12/4/2025 05:00 PM ET

Days: 30 | 90 | 365

Prothena Insider Trading History

Transaction Date	Insider Name	Title	Buy/Sell	Number of Shares	Average Share Price	Total Transaction	Shares Held After Transaction
1/14/2025	William P Scully	Major Shareholder	Buy	100,000	$12.79	$1,279,000.00	735,993
12/31/2024	William P Scully	Major Shareholder	Buy	32,000	$13.01	$416,320.00	650,193
12/20/2024	William P Scully	Major Shareholder	Buy	2,000	$15.91	$31,820.00	618,693
12/18/2024	William P Scully	Major Shareholder	Buy	73,436	$13.93	$1,022,963.48	1,297,693
1/24/2024	Karin L. Walker	CAO	Sell	5,000	$34.00	$170,000.00
12/20/2023	Karin L. Walker	CAO	Sell	5,000	$37.19	$185,950.00
11/30/2023	Karin L. Walker	CAO	Sell	5,000	$34.00	$170,000.00
10/25/2023	Karin L. Walker	CAO	Sell	5,000	$41.04	$205,200.00
10/11/2023	Brandon S. Smith	COO	Sell	4,000	$46.75	$187,000.00
10/4/2023	Carol D. Karp	insider	Sell	5,000	$46.62	$233,100.00
9/27/2023	Michael J. Malecek	insider	Sell	5,000	$47.38	$236,900.00
9/19/2023	Karin L. Walker	CAO	Sell	5,000	$52.36	$261,800.00
9/13/2023	Brandon S. Smith	COO	Sell	4,000	$55.49	$221,960.00
9/13/2023	Hideki Garren	insider	Sell	2,000	$55.48	$110,960.00
9/6/2023	Carol D. Karp	insider	Sell	5,000	$54.76	$273,800.00
8/30/2023	Michael J. Malecek	insider	Sell	5,000	$55.01	$275,050.00
8/18/2023	Karin L. Walker	CAO	Sell	5,000	$57.18	$285,900.00
8/16/2023	Brandon S. Smith	COO	Sell	4,000	$58.71	$234,840.00
8/16/2023	Hideki Garren	insider	Sell	2,000	$58.74	$117,480.00
8/2/2023	Wagner M. Zago	insider	Sell	4,000	$67.05	$268,200.00
7/26/2023	Michael J. Malecek	insider	Sell	5,000	$62.33	$311,650.00
7/19/2023	Karin L. Walker	CAO	Sell	5,000	$69.19	$345,950.00
7/12/2023	Brandon S. Smith	COO	Sell	4,000	$67.51	$270,040.00
7/12/2023	Hideki Garren	insider	Sell	2,000	$67.51	$135,020.00
7/5/2023	Carol D. Karp	insider	Sell	5,000	$68.13	$340,650.00
7/3/2023	Dennis J Selkoe	Director	Sell	5,000	$67.43	$337,150.00	2,845
6/28/2023	Michael J. Malecek	insider	Sell	5,000	$69.82	$349,100.00
6/16/2023	Hideki Garren	insider	Sell	7,331	$74.00	$542,494.00
6/14/2023	Brandon S. Smith	COO	Sell	5,333	$73.98	$394,535.34
6/14/2023	Hideki Garren	insider	Sell	4,669	$74.22	$346,533.18
6/7/2023	Wagner M. Zago	insider	Sell	19,000	$71.06	$1,350,140.00
5/31/2023	Michael J. Malecek	insider	Sell	5,000	$64.64	$323,200.00
5/19/2023	Karin L. Walker	CAO	Sell	5,000	$74.00	$370,000.00
5/17/2023	Gene G Kinney	CEO	Sell	45,000	$73.70	$3,316,500.00	12,793
5/17/2023	Tran Nguyen	CFO	Sell	95,000	$73.99	$7,029,050.00	3,200
5/3/2023	Dennis J Selkoe	Director	Sell	15,000	$57.00	$855,000.00	2,845
4/26/2023	Michael J. Malecek	insider	Sell	5,000	$53.46	$267,300.00
4/19/2023	Karin L. Walker	CAO	Sell	5,000	$52.90	$264,500.00
3/29/2023	Michael J. Malecek	insider	Sell	5,000	$49.02	$245,100.00
3/20/2023	Karin L. Walker	CAO	Sell	5,000	$47.72	$238,600.00
3/15/2023	Karin L. Walker	CAO	Sell	20,000	$48.42	$968,400.00
3/15/2023	Michael J. Malecek	insider	Sell	15,000	$48.44	$726,600.00
3/15/2023	Tran Nguyen	CFO	Sell	10,000	$48.43	$484,300.00	3,200
2/15/2023	Tran Nguyen	CFO	Sell	10,000	$53.34	$533,400.00	3,200
1/18/2023	Tran Nguyen	CFO	Sell	10,000	$55.53	$555,300.00	3,200
1/10/2023	Shane Cooke	Director	Sell	5,000	$52.92	$264,600.00
1/5/2023	Richard T Collier	Director	Sell	5,000	$52.67	$263,350.00	1,219
1/3/2023	Lars Ekman	Insider	Sell	15,834	$55.98	$886,387.32	243
12/21/2022	Tran Nguyen	CFO	Sell	10,000	$58.97	$589,700.00	3,200
12/12/2022	Shane Cooke	Director	Sell	5,000	$61.04	$305,200.00

SEC Filings (Institutional Ownership Changes) for Prothena (NASDAQ:PRTA)

97.08% of Prothena stock is owned by institutions. Institutional ownership can be a sign of analyst confidence in the fundamentals of the stock.

Institutional Buying and Selling by Quarter

Prothena Institutional Trading History

Reporting Date	Hedge Fund	Shares Held	Market Value	% of Portfolio	Quarterly Change in Shares	Ownership in Company
11/17/2025	Jacobs Levy Equity Management Inc.	876,528	$8.56M	0.0%	+26.5%	1.628%
11/17/2025	Armistice Capital LLC	1,824,000	$17.80M	0.3%	-18.4%	3.388%
11/17/2025	Proficio Capital Partners LLC	30,136	$0.29M	0.0%	N/A	0.056%
11/17/2025	Qube Research & Technologies Ltd	254,245	$2.48M	0.0%	-38.7%	0.472%
11/17/2025	Palo Alto Investors LP	1,324,028	$12.92M	2.4%	+3.9%	2.460%
11/17/2025	Mariner LLC	590,897	$5.77M	0.0%	+52.8%	1.098%
11/17/2025	Millennium Management LLC	621,099	$6.06M	0.0%	+264.1%	1.154%
11/17/2025	MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.	18,834	$0.18M	0.0%	-11.2%	0.035%
11/17/2025	Jain Global LLC	11,780	$0.12M	0.0%	-35.5%	0.022%
11/17/2025	Bank of America Corp DE	277,096	$2.70M	0.0%	+31.4%	0.515%
11/17/2025	Algert Global LLC	445,811	$4.35M	0.1%	+825.9%	0.828%
11/17/2025	Alliancebernstein L.P.	69,607	$0.68M	0.0%	-20.5%	0.129%
11/17/2025	Ameriprise Financial Inc.	105,536	$1.03M	0.0%	-30.4%	0.196%
11/14/2025	Creative Planning	64,140	$0.63M	0.0%	+26.8%	0.119%
11/14/2025	Raymond James Financial Inc.	22,032	$0.22M	0.0%	+63.2%	0.041%
11/14/2025	Sandia Investment Management LP	29,950	$0.29M	0.9%	N/A	0.056%
11/14/2025	Rubric Capital Management LP	1,540,373	$15.03M	0.2%	N/A	2.862%
11/14/2025	Man Group plc	131,973	$1.29M	0.0%	+208.7%	0.245%
11/14/2025	ADAR1 Capital Management LLC	1,469,098	$14.34M	1.3%	-56.5%	2.729%
11/14/2025	Arizona PSPRS Trust	27,700	$0.29M	0.0%	N/A	0.051%
11/14/2025	Brooklyn Investment Group	12,569	$0.12M	0.0%	+13.1%	0.023%
11/14/2025	Two Sigma Investments LP	426,605	$4.16M	0.0%	+111.8%	0.793%
11/14/2025	Squarepoint Ops LLC	127,033	$1.24M	0.0%	-39.3%	0.236%
11/14/2025	Prosight Management LP	20,000	$0.20M	0.0%	-92.5%	0.037%
11/13/2025	Arrowstreet Capital Limited Partnership	654,294	$6.39M	0.0%	N/A	1.215%
11/13/2025	UBS Group AG	400,847	$3.91M	0.0%	+560.8%	0.745%
11/13/2025	BNP Paribas Financial Markets	228,010	$2.23M	0.0%	+386.7%	0.424%
11/13/2025	Franklin Resources Inc.	61,172	$0.60M	0.0%	+9.1%	0.114%
11/13/2025	Legal & General Group Plc	3,599	$35K	0.0%	-61.4%	0.007%
11/13/2025	Russell Investments Group Ltd.	127,757	$1.25M	0.0%	+32.8%	0.237%
11/13/2025	Pinnacle Associates Ltd.	71,261	$0.70M	0.0%	-3.8%	0.132%
11/12/2025	DCF Advisers LLC	200,747	$1.96M	0.6%	+28.3%	0.373%
11/12/2025	Barclays PLC	98,075	$0.96M	0.0%	-15.3%	0.182%
11/12/2025	Dimensional Fund Advisors LP	806,988	$7.88M	0.0%	-16.1%	1.499%
11/12/2025	Intech Investment Management LLC	19,388	$0.19M	0.0%	+5.5%	0.036%
11/12/2025	Fox Run Management L.L.C.	44,332	$0.43M	0.1%	N/A	0.082%
11/10/2025	Ameritas Investment Partners Inc.	3,428	$33K	0.0%	-21.5%	0.006%
11/10/2025	China Universal Asset Management Co. Ltd.	9,436	$92K	0.0%	-12.7%	0.018%
11/7/2025	Vanguard Group Inc.	2,049,849	$20.01M	0.0%	-5.8%	3.808%
11/7/2025	JPMorgan Chase & Co.	735,765	$7.18M	0.0%	+479.6%	1.367%
11/6/2025	Rhumbline Advisers	62,042	$0.61M	0.0%	-1.5%	0.115%
11/6/2025	Oppenheimer & Co. Inc.	11,660	$0.11M	0.0%	-37.3%	0.022%
11/5/2025	Alps Advisors Inc.	25,727	$0.25M	0.0%	-11.4%	0.048%
11/4/2025	Thrivent Financial for Lutherans	12,980	$0.13M	0.0%	-66.4%	0.024%
11/3/2025	Great Lakes Advisors LLC	13,284	$0.13M	0.0%	N/A	0.025%
11/3/2025	Ballentine Partners LLC	18,310	$0.18M	0.0%	N/A	0.034%
11/3/2025	Federated Hermes Inc.	692,818	$6.76M	0.0%	-41.3%	1.287%
10/31/2025	Y Intercept Hong Kong Ltd	12,171	$0.12M	0.0%	N/A	0.023%
10/30/2025	Strs Ohio	28,800	$0.28M	0.0%	+75.6%	0.054%
10/30/2025	Covestor Ltd	31,432	$0.31M	0.2%	-25.7%	0.058%
10/29/2025	Inscription Capital LLC	10,480	$0.10M	0.0%	N/A	0.019%
10/23/2025	SG Americas Securities LLC	56,719	$0.55M	0.0%	+9.2%	0.105%
10/22/2025	Hennion & Walsh Asset Management Inc.	84,598	$0.83M	0.0%	-1.8%	0.157%
10/15/2025	CWM LLC	10,246	$100K	0.0%	+650.1%	0.019%
10/10/2025	Focused Wealth Management Inc	57,129	$0.56M	0.1%	+77.8%	0.106%
10/7/2025	Assenagon Asset Management S.A.	89,704	$0.88M	0.0%	N/A	0.167%
8/27/2025	Squarepoint Ops LLC	209,249	$1.27M	0.0%	N/A	0.389%
8/15/2025	Tower Research Capital LLC TRC	12,709	$77K	0.0%	+571.0%	0.024%
8/15/2025	Monimus Capital Management LP	206,475	$1.25M	0.9%	N/A	0.384%
8/15/2025	Voleon Capital Management LP	18,536	$0.11M	0.0%	N/A	0.034%
8/15/2025	Rangeley Capital LLC	715,367	$4.34M	5.4%	N/A	1.329%
8/15/2025	Man Group plc	42,752	$0.26M	0.0%	+151.5%	0.079%
8/15/2025	Engineers Gate Manager LP	40,967	$0.25M	0.0%	N/A	0.076%
8/15/2025	BNP Paribas Financial Markets	46,844	$0.28M	0.0%	+389.1%	0.087%
8/15/2025	Birchview Capital LP	451,019	$2.74M	2.7%	+35.5%	0.838%
8/15/2025	Balyasny Asset Management L.P.	575,792	$3.50M	0.0%	N/A	1.070%
8/15/2025	Bank of America Corp DE	210,945	$1.28M	0.0%	+59.8%	0.392%
8/15/2025	Ameriprise Financial Inc.	151,543	$0.92M	0.0%	N/A	0.282%
8/14/2025	PDT Partners LLC	41,281	$0.25M	0.0%	-72.5%	0.077%
8/14/2025	Quantinno Capital Management LP	59,618	$0.36M	0.0%	N/A	0.111%
8/14/2025	MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.	21,218	$0.13M	0.0%	-22.4%	0.039%
8/14/2025	Armistice Capital LLC	2,236,000	$13.57M	0.2%	+1.8%	4.154%
8/14/2025	The Manufacturers Life Insurance Company	15,140	$92K	0.0%	-76.8%	0.028%
8/14/2025	Squarepoint Ops LLC	209,249	$1.27M	0.0%	N/A	0.389%
8/14/2025	Nebula Research & Development LLC	22,857	$0.14M	0.0%	N/A	0.042%
8/14/2025	Qube Research & Technologies Ltd	414,828	$2.52M	0.0%	N/A	0.771%
8/14/2025	Federated Hermes Inc.	1,181,087	$7.17M	0.0%	+116.2%	2.194%
8/13/2025	Cresset Asset Management LLC	10,314	$63K	0.0%	-21.4%	0.019%
8/13/2025	New York State Common Retirement Fund	8,979	$55K	0.0%	-37.1%	0.017%
8/13/2025	Virtus Investment Advisers LLC	18,547	$0.11M	0.0%	+56.0%	0.034%
8/13/2025	Norges Bank	57,454	$0.35M	0.0%	N/A	0.107%
8/13/2025	Quadrature Capital Ltd	23,752	$0.14M	0.0%	N/A	0.044%
8/13/2025	Hsbc Holdings PLC	46,047	$0.28M	0.0%	+251.8%	0.086%
8/13/2025	Russell Investments Group Ltd.	96,196	$0.58M	0.0%	+7,956.6%	0.179%
8/12/2025	DCF Advisers LLC	156,500	$0.95M	0.4%	-19.7%	0.291%
8/12/2025	American Century Companies Inc.	59,965	$0.36M	0.0%	+72.1%	0.111%
8/12/2025	Rhumbline Advisers	63,005	$0.38M	0.0%	-4.7%	0.117%
8/12/2025	Franklin Resources Inc.	56,078	$0.34M	0.0%	+184.0%	0.104%
8/12/2025	Legal & General Group Plc	9,323	$57K	0.0%	-77.5%	0.017%
8/12/2025	JPMorgan Chase & Co.	126,951	$0.77M	0.0%	-65.9%	0.236%
8/12/2025	Swiss National Bank	56,500	$0.34M	0.0%	-17.8%	0.105%
8/8/2025	Intech Investment Management LLC	18,374	$0.11M	0.0%	-44.9%	0.034%
8/8/2025	Creative Planning	50,569	$0.31M	0.0%	+373.0%	0.094%
8/8/2025	SG Americas Securities LLC	51,941	$0.32M	0.0%	-28.4%	0.096%
8/8/2025	Geode Capital Management LLC	933,446	$5.67M	0.0%	-8.0%	1.734%
8/8/2025	PNC Financial Services Group Inc.	18,028	$0.11M	0.0%	+3,594.3%	0.033%
8/8/2025	Quinn Opportunity Partners LLC	50,000	$0.30M	0.0%	N/A	0.093%
8/7/2025	Monaco Asset Management SAM	70,000	$0.43M	0.1%	N/A	0.130%
8/7/2025	Acadian Asset Management LLC	1,018,177	$6.18M	0.0%	N/A	1.891%
8/7/2025	Connor Clark & Lunn Investment Management Ltd.	18,896	$0.12M	0.0%	-79.3%	0.035%

Data available starting January 2016

Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation in the United States. The company is involved in developing birtamimab, an investigational humanized antibody that is in Phase III clinical trial for the treatment of AL amyloidosis; Prasinezumab, a humanized monoclonal antibody, for the treatment of Parkinson's disease and other related synucleinopathies which is in Phase IIb clinical trial; NNC6019 that is in Phase lI clinical trial for the treatment of ATTR amyloidosis; and BMS-986446 and PRX012, which is in Phase I clinical trial for the treatment of Alzheimer's disease. Its discovery and preclinical programs include PRX123, a dual Aß-Tau vaccine for the treatment and prevention of Alzheimer's disease; and PRX019 for the treatment of neurogenerative diseases, as well as TDP-43 for the treatment of amyotrophic lateral sclerosis. Prothena Corporation plc has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target a-synuclein, including prasinezumab; and a collaboration agreement with Bristol-Myers Squibb to develop and commercialize antibodies targeting tau, TDP-43. The company was incorporated in 2012 and is based in Dublin, Ireland.

Today's Range

Now: $11.16

$10.95

$11.57

50 Day Range

MA: $10.27

$9.41

$11.17

52 Week Range

Now: $11.16

$4.32

$17.66

Volume

1,161,191 shs

Average Volume

569,200 shs

Market Capitalization

$600.74 million

P/E Ratio

N/A

Dividend Yield

N/A

Beta

N/A

Who are the company insiders with the largest holdings of Prothena?: Prothena's top insider shareholders include:
William P Scully (Major Shareholder)
Karin L Walker (CAO)
Learn More about top insider investors at Prothena.
Who are the major institutional investors of Prothena?: Prothena's top institutional shareholders include:
Vanguard Group Inc. — 3.81%
Armistice Capital LLC — 3.39%
Rubric Capital Management LP — 2.86%
ADAR1 Capital Management LLC — 2.73%
Palo Alto Investors LP — 2.46%
Jacobs Levy Equity Management Inc. — 1.63%
Learn More about top institutional investors of Prothena stock.
Which major investors are selling Prothena stock?: During the previous quarter, PRTA stock was sold by these institutional investors:
ADAR1 Capital Management LLC
Federated Hermes Inc.
Armistice Capital LLC
Prosight Management LP
Qube Research & Technologies Ltd
Dimensional Fund Advisors LP
Vanguard Group Inc.
Squarepoint Ops LLC
Which major investors are buying Prothena stock?: In the last quarter, PRTA stock was bought by institutional investors including:
Rubric Capital Management LP
Arrowstreet Capital Limited Partnership
JPMorgan Chase & Co.
Millennium Management LLC
Algert Global LLC
UBS Group AG
Susquehanna International Group LLP
Two Sigma Investments LP