Prothena Corp Public Ltd Co (PRTA) Institutional Ownership

Institutions by Trading Activity

52,656,180Shares Outstanding

13,709,718Shares held by institutions

$125,992,308Value of institutional holdings

98.56%Institutional ownership %

2.39%Shares Changed QoQ

193No. of institutional investors

According to SEC filings for the period ending December 2025, Prothena Corp Public Ltd Co (NASDAQ:PRTA) is held by 6 institutional firms.

Prothena Corp Public saw its institutional ownership percentage fell to 0.3% in December 2025 from 80.0% in September 2025.
Quarterly data indicates a -4.37% shift in institutional share volume, and the annual owner count reflects a decrease of 96.47%.
The latest 13F cycle for Prothena Corp Public reveals that of 6 total investors, 2 funds grew their exposure, whereas 1 reduced theirs and 3 made no changes.
Collectively, institutional investors decreased their stake in Prothena Corp Public to 142.54K shares as of December 2025, a change that is down by 6.51K shares quarter on quarter and down 53.57Mn shares year over year.
As of December 31, 2025, Assenagon Asset Management S.A. held Prothena Corp Public's largest shareholding position with over 76.77K shares, representing 0.14% of total outstanding shares.
Among the most significant buyers of Prothena Corp Public during December 2025 were SG Americas Securities, LLC (6.30K), GAMMA Investing LLC (124).
Leading sellers of Prothena Corp Public stock in December 2025 included Assenagon Asset Management S.A. (12.94K).
The top 6 institutional holders of Prothena Corp Public for the quarter ending December 2025 included Assenagon Asset Management S.A. (76.77K), SG Americas Securities, LLC (63.02K), Versant Capital Management, Inc (2.04K), GAMMA Investing LLC (510), True Wealth Design, LLC (103), HARBOR INVESTMENT ADVISORY, LLC (100).

13,709,718 Total Shares Held

Rows:

Owner Name	Date	Shares Held	Change (QoQ)	Change (%)	Value (USD)
FMR LLC	30 Sep, 2025	7,901,218	0	0.00%	$77,115,888.00
BlackRock, Inc.	30 Sep, 2025	3,598,417	-340,981	-8.66%	$35,120,550.00
VANGUARD GROUP INC	30 Sep, 2025	2,049,849	-126,378	-5.81%	$20,006,526.00
ARMISTICE CAPITAL, LLC	30 Sep, 2025	1,824,000	-412,000	-18.43%	$17,802,240.00
Rubric Capital Management LP	30 Sep, 2025	1,540,373	1,540,373	0.00%	$15,034,040.00
ADAR1 Capital Management, LLC	30 Sep, 2025	1,469,098	-1,905,911	-56.47%	$14,338,396.00
Palo Alto Investors LP	30 Sep, 2025	1,324,028	49,275	3.87%	$12,922,513.00
D. E. Shaw & Co., Inc.	30 Sep, 2025	1,315,418	923,923	236.00%	$12,838,480.00
ACADIAN ASSET MANAGEMENT LLC	30 Sep, 2025	1,239,242	221,065	21.71%	$12,090.00
GEODE CAPITAL MANAGEMENT, LLC	30 Sep, 2025	1,019,483	86,037	9.22%	$9,952,225.00
STATE STREET CORP	30 Sep, 2025	901,038	-103,964	-10.34%	$8,794,131.00
JANE STREET GROUP, LLC	30 Sep, 2025	879,192	562,539	177.65%	$8,580,914.00
JACOBS LEVY EQUITY MANAGEMENT, INC	30 Sep, 2025	876,528	183,374	26.46%	$8,554,913.00
DIMENSIONAL FUND ADVISORS LP	30 Sep, 2025	806,988	-155,351	-16.14%	$7,876,161.00
MORGAN STANLEY	30 Sep, 2025	799,674	-153,582	-16.11%	$7,804,823.00
CITADEL ADVISORS LLC	30 Sep, 2025	767,105	767,105	0.00%	$7,486,945.00
JPMORGAN CHASE & CO	30 Sep, 2025	735,765	608,814	479.57%	$7,181,066.00
FEDERATED HERMES, INC.	30 Sep, 2025	692,818	-488,269	-41.34%	$6,761,904.00
Nuveen, LLC	30 Sep, 2025	668,290	546,135	447.08%	$6,522,511.00
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	30 Sep, 2025	654,294	654,294	0.00%	$6,385,909.00

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