Estimated market cap $419.01MShares outstanding from the company’s latest SEC filing (all share classes, each priced at its own close; ADRs converted to ADS) × last close from Tiingo. Updated daily. This figure: shares as of Oct 29, 2026, last close Nov 13, 2026.51.35M shares, shares as of Oct 29, 2026CIK 1559053The SEC’s Central Index Key, the number it uses to identify every company and person that files.
Insider trades, 12 mo
15 buys · 2 sells
$135.9K sold, open market
Congress trades, 24 mo
—
No disclosed trades
13F holders
…
Lobbying, 12 mo
—
No lobbying filings
Federal contracts, 12 mo
—
None matched
Ask your AI:
Latest 10-Q
What changed in Prothena Corporation plc's latest quarterly report, compared with the one before.
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Insider trades
Open-market trades from Form 4. 10b5-1 marks a plan set in advance.Open-market buys and sales by officers, directors and 10% owners, from SEC Form 4. A plan set in advance is marked 10b5-1.
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13F holders
Funds that report this stock, checked against market prices.Fund managers with over $100 million in US-listed stocks file a 13F each quarter, up to 45 days after quarter end. Long positions only.
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Top 10 holders.Premium lists every holder, with CSV downloads.
Disclosed in dollar ranges, up to 45 days after the trade.Members of Congress, their spouses and dependent children report trades in dollar ranges, up to 45 days after the trade.
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Lobbying
What Prothena Corporation plc and its lobbying firms report each quarter.A company that lobbies with its own staff reports its expenses; a lobbying firm it hires reports the income it received. We count both.
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Institutional ownership over time
How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.
13F holders, Q3 2026Fund managers with over $100 million in US-listed stocks file a 13F each quarter, up to 45 days after quarter end. Long positions only.
117
55.7% of shares · 39 added
Latest 10-Q
Q3 2026
What changed in Prothena Corporation plc's latest quarterly report, compared with the one before.
Filed Nov 5, 2026 · Quarter ended Sep 30, 2026
Summary text goes here once it has loaded. Summary text goes here once it has loaded.
Summary text goes here once it has loaded.
Summary text goes here once it has loaded.
AI summary of changes vs the prior report. Written by AI from the paragraphs that changed, and checked against them. This is information, not investment advice.
Compared with the 10-Q for the quarter ended Jun 30, 2026. Sections compared: management's discussion, risk factors, legal proceedings and controls and procedures.
Open-market trades from Form 4. 10b5-1 marks a plan set in advance.Open-market buys and sales by officers, directors and 10% owners, from SEC Form 4. A plan set in advance is marked 10b5-1.
Recent insider trades
How the stock has done since the trade date, measured against the S&P 500 over the same days. It describes the stock, not the trader's actual gain or loss.
117 funds report PRTA. Values checked against market prices.Fund managers with over $100 million in US-listed stocks file a 13F each quarter, up to 45 days after quarter end. Long positions only.
Funds own 92% of shares (Q2 2026)Fund managers with more than $100 million in US-listed stocks file a 13F each quarter. It lists their long stock positions only (shorts, options and bonds are left out) and can arrive up to 45 days after the quarter ends, so this is a snapshot of the quarter end. We add up the shares every fund reports in this class and divide by the shares outstanding. The total can pass 100%: the same shares are often reported by more than one manager (an adviser and the fund it runs), lent shares can be reported twice, and the share count can be out of date after buybacks. We divided 47.32M reported shares by 51.34M shares, from the company’s SEC filing as of Jul 30, 2026.
190 funds hold the stock.
Q3 2026: 56% · 5,560 of ~8,900 funds reported so farFunds have 45 days after a quarter ends to file. This quarter’s reports are still arriving, so the figure only counts the funds that have filed so far and will usually rise.
Q2 202578%
Q3 202581%
Q4 202588%
Q1 202690%
Q2 202692%
Q3 2026 (so far)56%
Q3 2026. 13 new, 39 added to, 33 trimmed, 86 exited since Q2 2026.
One of these funds reports its values in thousands of dollars; its figures are shown in dollars.
Download CSVEvery fund that holds PRTA, not only these ten. A download holds at most 10,000 rows; narrow the filters to get a smaller slice.
Trades by members of Congress
Disclosed in dollar ranges, up to 45 days after the trade.Members of Congress, their spouses and dependent children report trades in dollar ranges, up to 45 days after the trade.
Recent congressional trades
How the stock has done since the trade date, measured against the S&P 500 over the same days. It describes the stock, not the trader's actual gain or loss.
What Prothena Corporation plc and its lobbying firms report each quarter.A company that lobbies with its own staff reports its expenses; a lobbying firm it hires reports the income it received. We count both.
No recent lobbying filings for this company.
Institutional ownership over time
How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.
Funds holding the stock
Shares they report
Funds holding the stock by quarter
Q2 2013
82
—
9.55M
$123.3M
Q3 2013
88
+6
9.12M
$184.5M
Q4 2013
106
+18
17.65M
$468.1M
Q1 2014
116
+10
21.43M
$820.5M
Q2 2014
130
+14
22.62M
$510.2M
Q3 2014
125
-5
21.50M
$476.4M
Q4 2014
126
+1
24.78M
$516.6M
Q1 2015
123
-3
25.41M
$968.4M
Q2 2015
135
+12
29.46M
$1.6B
Q3 2015
144
+9
30.10M
$1.4B
Q4 2015
158
+14
30.08M
$2.0B
Q1 2016
141
-17
35.32M
$1.5B
Q2 2016
141
0
34.72M
$1.2B
Q3 2016
142
+1
35.92M
$2.2B
Q4 2016
145
+3
38.02M
$1.9B
Q1 2017
146
+1
41.63M
$2.3B
Q2 2017
145
-1
42.52M
$2.3B
Q3 2017
153
+8
43.10M
$2.8B
Q4 2017
155
+2
43.34M
$1.6B
Q1 2018
142
-13
42.23M
$1.6B
Q2 2018
125
-17
41.89M
$610.8M
Q3 2018
130
+5
41.24M
$539.7M
Q4 2018
120
-10
40.69M
$419.0M
Q1 2019
139
+19
39.57M
$480.0M
Q2 2019
138
-1
38.99M
$411.9M
Q3 2019
130
-8
37.67M
$295.3M
Q4 2019
141
+11
37.62M
$595.4M
Q1 2020
129
-12
37.35M
$399.7M
Q2 2020
139
+10
37.86M
$396.1M
Q3 2020
140
+1
36.21M
$361.8M
Q4 2020
140
0
34.82M
$418.2M
Q1 2021
146
+6
39.99M
$1.0B
Q2 2021
156
+10
40.60M
$2.1B
Q3 2021
192
+36
40.93M
$2.9B
Q4 2021
196
+4
43.08M
$2.1B
Q1 2022
173
-23
44.15M
$1.6B
Q2 2022
166
-7
44.57M
$1.2B
Q3 2022
183
+17
44.64M
$2.7B
Q4 2022
201
+18
49.39M
$3.0B
Q1 2023
191
-10
58.52M
$2.8B
Q2 2023
196
+5
51.95M
$3.5B
Q3 2023
186
-10
53.17M
$2.6B
Q4 2023
187
+1
54.71M
$2.0B
Q1 2024
169
-18
55.26M
$1.4B
Q2 2024
160
-9
51.44M
$1.1B
Q3 2024
164
+4
51.39M
$862.7M
Q4 2024
170
+6
53.82M
$745.5M
Q1 2025
162
-8
52.32M
$647.4M
Q2 2025
189
+27
41.87M
$254.2M
Q3 2025
189
0
43.40M
$423.5M
Q4 2025
183
-6
47.31M
$452.1M
Q1 2026
186
+3
46.98M
$456.6M
Q2 2026
190
+4
47.32M
$465.6M
Q3 2026
117
-73
28.61M
$239.8M
Each point is a quarter-end, from Q2 2013 to Q3 2026. A fund's 13F lists its long positions in US-listed securities as of the last day of the quarter and arrives up to 45 days later, so each point shows holdings at quarter-end, not on the day they were reported.
Common shares only; options and bonds are left out. When a fund amends a report, the amended version is the one counted.
The history follows the company's current CUSIP number (G72800108). If the company's shares were ever re-issued under a different CUSIP, the quarters before the change are not part of this series, so the first point (Q2 2013) can be later than the stock's first appearance in 13F reports.
Share counts are adjusted for stock splits; none took place between these quarters. Values are in dollars as reported at the time and are not adjusted.
A quarter appears once our daily update has built its summary. If a summary cannot be built, older reports are kept and the chart shows the quarters it has until the next update repairs it.