Prothena Ownership | Who Owns Prothena?

Overview Forecast RevenueFinancials Chart Transcripts

Prothena Ownership Summary

Prothena is owned by 88.66% institutional investors, 21.10% insiders. Fmr is the largest institutional shareholder, holding 13.40% of PRTA shares. Vanguard Health Care Inv is the top mutual fund, with 7.77% of its assets in Prothena shares.

PRTA Ownership Benchmark

Type	Name	% Inst	% Insiders	% Retail
Stock	Prothena	88.66%	21.10%	-9.76%
Sector	Healthcare Stocks	246.48%	12.12%	-158.60%
Industry	Biotech Stocks	384.82%	11.76%	-296.58%

Institutional Shareholders

Top Institutional Shareholders by Total Shares

Holder	Shares	% Holding	Value
Fmr	7.20M	13.40%	$70.48M
Rubric capital management lp	5.00M	9.31%	$48.95M
Blackrock funding, inc. /de	4.87M	9.06%	$47.66M
Blackrock	3.86M	7.18%	$79.61M
State street	2.39M	4.46%	$23.43M
Vanguard group	2.14M	3.98%	$20.45M
Acadian asset management	2.01M	3.74%	$19.68M
D. e. shaw	1.61M	3.00%	$15.78M
Adar1 capital management	1.55M	2.89%	$15.22M
Two sigma investments, lp	1.26M	2.36%	$12.38M

Top Institutional Shareholders by % of Total Assets

Holder	Shares	% Assets	Value
Rangeley capital	417.27K	3.73%	$4.09M
Birchview capital, lp	449.02K	2.06%	$4.40M
Palo alto investors lp	1.14M	1.55%	$11.19M
Penbrook management	271.72K	1.34%	$2.28M
Sandia investment management lp	29.95K	0.87%	$292.31K
Boxer capital	690.00K	0.75%	$14.24M
Monimus capital management, lp	329.05K	0.75%	$3.22M
Adar1 capital management	1.55M	0.70%	$15.22M
Artal group	1.00M	0.53%	$20.67M
Rubric capital management lp	5.00M	0.45%	$48.95M

Top Buyers

Holder	Shares	% Assets	Change
Balyasny asset management	575.79K	0.01%	575.79K
Acadian asset management	2.01M	0.02%	463.05K
State street	2.39M	0.00%	454.93K
Algert global	445.81K	0.07%	397.66K
Sixth street partners management company	355.90K	0.00%	355.90K

Top Sellers

Holder	Shares	% Assets	Change
Ecor1 capital	-	-	-11.58M
Siren	-	-	-1.28M
Finepoint capital lp	-	-	-640.07K
Rock springs capital management lp	25.40K	0.01%	-467.20K
Granahan investment management	-	-	-461.08K

New Positions

Holder	Shares	% Assets	Change	Value
Sixth street partners management company	355.90K	0.00%	355.90K	$3.48M
Mackenzie financial	239.90K	0.00%	239.90K	$2.35M
State of wisconsin investment board	70.33K	0.00%	70.33K	$688.49K
Norges bank	57.45K	0.00%	57.45K	$795.74K
Engineers gate manager lp	41.27K	0.01%	41.27K	$404.03K

Sold Out

Holder	Change
Wealth preservation advisors	-1.00
Koesten, hirschmann & crabtree	-1.00
Truvestments capital	-1.00
Jfs wealth advisors	-2.00
Assetmark	-2.00

Institutional Ownership Trends

Date	Holdings	Change %	Shares	Change %	Ownership	Change %	Increased Position	Change %	Decreased Position	Change %
Jun 30, 2026	195	1.04%	47,615,367	1.35%	88	1.16%	89	-9.18%	57	14.00%
Mar 31, 2026	186	-3.63%	45,019,824	-4.73%	83	1.09%	96	18.52%	49	-20.97%
Dec 31, 2025	80	-60.00%	12,971,151	-69.58%	24	0.38%	30	-67.39%	25	-58.33%
Sep 30, 2025	79	-60.70%	11,520,268	-72.42%	21	0.36%	36	-66.67%	20	-51.22%
Jun 30, 2025	198	17.86%	41,726,109	-20.15%	77	0.82%	107	81.36%	41	-33.87%

Top Mutual Funds Shareholders

Holder	Shares	% Holding	Change
Vanguard Health Care Inv	4.18M	7.77%	-39.90K
Fidelity Growth Compy Commingled Pl S	3.34M	6.37%	-94.30K
Fidelity Growth Compy Commingled Pl O	3.28M	6.09%	1.22K
Fidelity Growth Company Fund	2.19M	4.26%	-43.30K
US Small-Cap Growth II Equity Comp	1.64M	3.04%	-251.90K
T. Rowe Price New Horizons	1.64M	3.04%	-251.35K
iShares Russell 2000 ETF	1.12M	2.18%	-12.93K
State Street® SPDR® S&P® Biotech ETF	910.08K	1.77%	-17.40K
Vanguard Explorer Inv	757.20K	1.45%	139.98K
Fidelity Series Growth Company	723.71K	1.41%	-14.30K

Recent Insider Transactions

Date	Name	Role	Activity	Value
Oct 14, 2026	SCULLY WILLIAM P	-	Buy	$84.57K
Oct 13, 2026	SCULLY WILLIAM P	-	Buy	$835.48K
Oct 07, 2026	SCULLY WILLIAM P	-	Buy	$1.05M
Oct 08, 2026	SCULLY WILLIAM P	-	Buy	$770.90K
Oct 02, 2026	SCULLY WILLIAM P	-	Buy	$857.24K

Insider Transactions Trends

Date	Buy	Sell
2026 Q4	5	-
2026 Q3	7	2
2026 Q2	5	-
2026 Q1	-	-
2025 Q3	-	-

PRTA Ownership FAQ

Who Owns Prothena?

Prothena shareholders are primarily institutional investors at 88.66%, followed by 21.10% insiders and -9.76% retail investors. The average institutional ownership in Prothena's industry, Biotech Stocks , is 384.82%, which Prothena falls below.

Who owns the most shares of Prothena?

Prothena’s largest shareholders are Fmr (7.2M shares, 13.40%), Rubric capital management lp (5M shares, 9.31%), and Blackrock funding, inc. /de (4.87M shares, 9.06%). Together, they hold 31.78% of Prothena’s total shares outstanding.

Does Blackrock own Prothena?

Yes, BlackRock owns 7.18% of Prothena, totaling 3.86M shares as of Jun 2024. This represents 0.00% of BlackRock's total assets, with a market value of 79.61M$. In the last quarter, BlackRock increased its holdings by 138.27K shares, a 3.72% change.

Who is Prothena’s biggest shareholder by percentage of total assets invested?

Rangeley capital is Prothena’s biggest shareholder by percentage of total assets invested, with 3.73% of its assets in 417.27K Prothena shares, valued at 4.09M$.

Who is the top mutual fund holder of Prothena shares?

Vanguard Health Care Inv is the top mutual fund holder of Prothena shares, with 7.77% of its total shares outstanding invested in 4.18M Prothena shares.

Try Tickergate Pro Free

Customize Everything. 100% Flexibility. Fast and Easy to Use (No code or Excel Needed)

Customize your own personal stocks lists, views and charts
Choose from hundreds of fields, up to 15 years of history
Conduct deep comparison analysis

Discover trending investment themes
Find your next best investment
Research stocks using tools