PRTA Insider Trading

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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

^$10.53

▼ -0.03 (-0.28%)

As of 11/10/2025 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
12/5/2022	Richard T Collier	Director	Sell	5,000	$62.07	$310,350.00	1,219
11/30/2022	Michael J. Malecek	insider	Sell	5,000	$62.28	$311,400.00	243
11/23/2022	Tran Nguyen	CFO	Sell	10,000	$61.09	$610,900.00	3,200
11/18/2022	Karin L. Walker	CAO	Sell	10,000	$57.07	$570,700.00

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
11/10/2025	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%
8/7/2025	Los Angeles Capital Management LLC	16,702	$0.10M	0.0%	N/A	0.031%
8/6/2025	Prospera Financial Services Inc	10,000	$61K	0.0%	N/A	0.019%
8/5/2025	Corton Capital Inc.	13,964	$85K	0.1%	N/A	0.026%
8/1/2025	Purkiss Capital Advisors LLC	24,904	$0.15M	0.1%	+15.1%	0.046%
7/29/2025	Nordea Investment Management AB	311,605	$1.92M	0.0%	+1.2%	0.579%
7/15/2025	Public Employees Retirement System of Ohio	42,158	$0.26M	0.0%	N/A	0.078%
7/10/2025	Mogy Joel R Investment Counsel Inc.	20,750	$0.13M	0.0%	N/A	0.039%
6/27/2025	Goldman Sachs Group Inc.	510,462	$6.32M	0.0%	-8.3%	0.948%
5/23/2025	Siren L.L.C.	1,283,555	$15.88M	0.9%	+16.7%	2.385%
5/16/2025	Goldman Sachs Group Inc.	510,462	$6.32M	0.0%	-8.3%	0.948%
5/16/2025	Jacobs Levy Equity Management Inc.	18,553	$0.23M	0.0%	N/A	0.034%
5/15/2025	Birchview Capital LP	332,974	$4.12M	3.5%	+9.3%	0.619%
5/15/2025	Palo Alto Investors LP	1,659,734	$20.54M	3.9%	-4.5%	3.083%
5/15/2025	PDT Partners LLC	150,316	$1.86M	0.1%	+18.2%	0.279%
5/15/2025	Armistice Capital LLC	2,196,000	$27.18M	0.4%	-1.8%	4.080%
5/15/2025	Siren L.L.C.	1,283,555	$15.88M	0.9%	+16.7%	2.385%
5/14/2025	Rafferty Asset Management LLC	43,978	$0.54M	0.0%	-43.4%	0.082%
5/14/2025	Price T Rowe Associates Inc. MD	3,455,856	$42.77M	0.0%	-6.2%	6.420%
5/14/2025	Hsbc Holdings PLC	13,088	$0.16M	0.0%	-45.9%	0.024%
5/14/2025	Wellington Management Group LLP	5,199,528	$64.34M	0.0%	+1.3%	9.660%
5/13/2025	Cresset Asset Management LLC	13,125	$0.16M	0.0%	-32.5%	0.024%
5/13/2025	American Century Companies Inc.	34,836	$0.43M	0.0%	+14.6%	0.065%
5/12/2025	Nuveen LLC	149,961	$1.86M	0.0%	N/A	0.279%
5/12/2025	Invesco Ltd.	37,638	$0.47M	0.0%	-12.2%	0.070%
5/9/2025	Chicago Partners Investment Group LLC	14,512	$0.18M	0.0%	+29.6%	0.027%
5/9/2025	Charles Schwab Investment Management Inc.	319,607	$3.96M	0.0%	-2.3%	0.594%
5/9/2025	DCF Advisers LLC	195,000	$2.41M	1.2%	+88.4%	0.362%
5/8/2025	Federated Hermes Inc.	546,255	$6.76M	0.0%	-26.8%	1.015%
5/7/2025	Purkiss Capital Advisors LLC	21,629	$0.27M	0.2%	+101.6%	0.040%
5/7/2025	TD Asset Management Inc	62,694	$0.78M	0.0%	-3.1%	0.116%
5/6/2025	Pinnacle Associates Ltd.	100,259	$1.24M	0.0%	-2.7%	0.186%
5/6/2025	KLP Kapitalforvaltning AS	6,700	$83K	0.0%	-48.1%	0.012%
4/30/2025	Alps Advisors Inc.	37,956	$0.47M	0.0%	-12.8%	0.071%
4/29/2025	Bank of New York Mellon Corp	146,009	$1.81M	0.0%	-2.8%	0.271%
4/24/2025	HighMark Wealth Management LLC	2,018	$25K	0.0%	-81.9%	0.004%
4/22/2025	Cambridge Investment Research Advisors Inc.	10,164	$0.13M	0.0%	N/A	0.019%

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: $10.53

$10.47

$11.09

50 Day Range

MA: $9.54

$8.06

$10.75

52 Week Range

Now: $10.53

$4.32

$18.60

Volume

694,728 shs

Average Volume

980,122 shs

Market Capitalization

$566.83 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%
JPMorgan Chase & Co. — 1.37%
Federated Hermes Inc. — 1.29%
Assenagon Asset Management S.A. — 0.17%
Hennion & Walsh Asset Management Inc. — 0.16%
Rhumbline Advisers — 0.12%
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:
Federated Hermes Inc.
Vanguard Group Inc.
Thrivent Financial for Lutherans
Covestor Ltd
Oppenheimer & Co. Inc.
Alps Advisors Inc.
Hennion & Walsh Asset Management Inc.
China Universal Asset Management Co. Ltd.
Which major investors are buying Prothena stock?: In the last quarter, PRTA stock was bought by institutional investors including:
JPMorgan Chase & Co.
Assenagon Asset Management S.A.
Focused Wealth Management Inc
Ballentine Partners LLC
Great Lakes Advisors LLC
Strs Ohio
Y Intercept Hong Kong Ltd
Inscription Capital LLC