Prothena Corp Public PRTA Insider Ownership

NASDAQ PRTA
$9.72 +0.12 (+1.25%)
As of: Sep 4, 2026 · 11:48 AM EDT

Insider Holdings by Owner

6.53Mn Shares

Insider Ownership Statistics

as of 30 Sep, 2026
Insider Ownership
2.37%
+0.071% pp QoQ
Shares Held by Insiders
1.27Mn
filed for Sep 2026
+3.07% QoQ
Shares Outstanding
53.83Mn
53,830,000 shares
Direct Holdings
1.19Mn
Indirect: 83.50K
Net Shares Traded (QoQ)
+37.97K
net buying in Sep 2026
Insiders Holding Shares
14
with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding
Latest
Average ownership
Peak ownership

Shares Purchased/Sold by Insiders

Bought Sold
Latest quarter
Net over range
Buying quarters

Insider Ownership Summary

Quarter ending 30 Sep, 2026

PRTA's three largest insider shareholders as of August 29, 2026 are Capital, Llc Ecor1 (TenPercentOwner, 11.58Mn shares), Capital, Llc Ecor1 (TenPercentOwner, 11.58Mn shares), Capital, Llc Ecor1 (TenPercentOwner, 5.30Mn shares).

Form 4 Holdings

Insiders Holding PRTA

Insiders 14
Shares held 6.53Mn
Of outstanding 12.12%
# Insider Position Direct Indirect Total Share of Insiders Last Filed
1 Capital, Llc Ecor1 TenPercentOwner 0 5,304,596 5,304,596 81.3% 06 May, 2025
2 William P Scully TenPercentOwner 800,000 0 800,000 12.3% 21 Aug, 2026
3 Michael J Malecek Chief Legal Officer 80,000 0 80,000 1.2% 30 Jul, 2025
4 Gene G. Kinney President And Ceo 68,793 0 68,793 1.1% 30 Jul, 2026
5 Anne Evans Kingston Chief Strategy Officer 55,782 0 55,782 0.9% 30 Jul, 2026
6 Brandon S. Smith Chief Operating Officer 52,000 0 52,000 0.8% 30 Jul, 2026
7 Chad J. Swanson Chief Development Officer 40,733 0 40,733 0.6% 30 Jul, 2026
8 Tran Nguyen Chief Strategy Officer And Cfo 40,205 0 40,205 0.6% 30 Jul, 2026
9 Michael John Isaacs General Counsel Company Sec. 35,745 0 35,745 0.5% 30 Jul, 2026
10 Wagner M. Zago Chief Scientific Officer 34,000 0 34,000 0.5% 30 Jul, 2026
11 Karin L Walker Chief Accounting Officer 10,000 0 10,000 0.2% 30 Jul, 2026
12 Dennis J. Selkoe Director 2,845 0 2,845 0.0% 03 Jul, 2023
13 Richard T Collier Director 1,219 0 1,219 0.0% 05 Jan, 2023
14 Lars Ekman Director, Other 243 0 243 0.0% 05 Jan, 2023

Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.

Form 4 Filings

1,612 Insider Transactions

Source SEC Form 4
Latest quarter Sep 2026
Download Data
Date Insider Position Transaction Shares Price Value Shares Held After Ownership
20 Aug, 2026 William P Scully TenPercentOwner Acquired P 50,000 $8.79 $439.43K 800,000 Direct
17 Aug, 2026 William P Scully TenPercentOwner Acquired G 336,000 $0.00 $0 1,377,553 Direct
18 Aug, 2026 William P Scully TenPercentOwner Disposed G 627,553 $0.00 $0 750,000 Direct
10 Aug, 2026 William P Scully TenPercentOwner Acquired G 251,553 $0.00 $0 1,041,553 Direct
07 Aug, 2026 William P Scully TenPercentOwner Acquired P 34,000 $8.62 $293.05K 790,000 Direct
07 Aug, 2026 William P Scully TenPercentOwner Acquired P 3,500 $8.62 $30.17K 83,500 Indirect
28 Jul, 2026 Karin L Walker Chief Accounting Officer Acquired M 15,000 25,000 Direct
28 Jul, 2026 Michael John Isaacs General Counsel Company Sec. Disposed F 4,694 $8.56 $40.18K 44,131 Direct
28 Jul, 2026 Tran Nguyen Chief Strategy Officer And Cfo Acquired M 57,000 97,205 Direct
28 Jul, 2026 Wagner M. Zago Chief Scientific Officer Acquired M 51,000 85,000 Direct
28 Jul, 2026 Chad J. Swanson Chief Development Officer Acquired M 51,000 85,000 Direct
28 Jul, 2026 Brandon S. Smith Chief Operating Officer Acquired M 78,000 130,000 Direct
28 Jul, 2026 Gene G. Kinney President And Ceo Acquired M 84,000 152,793 Direct
28 Jul, 2026 Anne Evans Kingston Chief Strategy Officer Disposed F 3,498 $8.56 $29.94K 63,444 Direct
28 Jul, 2026 Brandon S. Smith Chief Operating Officer Disposed D 78,000 $8.56 $667.68K 52,000 Direct
28 Jul, 2026 Tran Nguyen Chief Strategy Officer And Cfo Disposed D 57,000 $8.56 $487.92K 40,205 Direct
28 Jul, 2026 Chad J. Swanson Chief Development Officer Disposed D 40,800 $8.56 $349.25K 44,200 Direct
28 Jul, 2026 Karin L Walker Chief Accounting Officer Disposed D 15,000 $8.56 $128.40K 10,000 Direct
28 Jul, 2026 Wagner M. Zago Chief Scientific Officer Disposed D 51,000 $8.56 $436.56K 34,000 Direct
28 Jul, 2026 Gene G. Kinney President And Ceo Disposed D 84,000 $8.56 $719.04K 68,793 Direct