PRTA insider buying and SEC filings, explained
Prothena Corp. Public Ltd. Co. · CIK 1559053
Tracked: Forms 3/4/5, 8-K, NT · All filings on sec.gov
Insider activity in the last 12 months
Bought
$12.1M
Insiders who bought
1
Sold (not marked 10b5-1)
$0
Planned sales (10b5-1)
$136K
Insider purchases and sales, last 12 months
| Traded | Type | What was filed | Source |
|---|---|---|---|
| Oct 22–23, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 150,000 shares between Oct 22 and Oct 23 at about $8.15 ($1.2M), reported as a purchase (code P). Holdings up 14% to 1,187,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Oct 26, 2026, 4:20 PM ET |
| Oct 13–14, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 110,000 shares between Oct 13 and Oct 14 at about $8.36 ($920K), reported as a purchase (code P). Holdings up 12% to 1,037,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Oct 15, 2026, 4:21 PM ET |
| Oct 7–8, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 215,000 shares indirectly (by spouse) between Oct 7 and Oct 8 at about $8.47 ($1.8M), reported as a purchase (code P). Holdings by spouse up 68% to 529,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Oct 9, 2026, 9:43 AM ET |
| Oct 2, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 100,000 shares indirectly (by spouse) at about $8.57 ($857K), reported as a purchase (code P). Holdings by spouse up 47% to 314,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Oct 6, 2026, 1:53 PM ET |
| Sep 29, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 162,000 shares indirectly (by spouse) at about $8.68 ($1.4M), reported as a purchase (code P). Holdings by spouse up 312% to 214,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Sep 30, 2026 |
| Sep 28, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 103,500 shares indirectly (by entity) at about $8.60 ($890K), reported as a purchase (code P). Holdings by entity up 124% to 187,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Sep 29, 2026 |
| Sep 18, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 100,000 shares at about $8.43 ($843K), reported as a purchase (code P). Holdings up 12% to 927,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Sep 21, 2026 |
| Sep 2, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 27,000 shares at about $9.47 ($256K), reported as a purchase (code P). Holdings up 3% to 827,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Sep 3, 2026 |
| Aug 20, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 50,000 shares at about $8.79 ($440K), reported as a purchase (code P). Holdings up 7% to 800,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 21, 2026 |
| Aug 7, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 37,500 shares directly and indirectly (by entity) at about $8.62 ($323K), reported as a purchase (code P). Direct holdings up 4% to 790,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 10, 2026 |
| Jul 29, 2026 | Planned (10b5-1) | Anne Evans Kingston (Chief Strategy Officer) sold 7,662 shares at about $8.47 ($65K), marked as a 10b5-1 plan trade. Holdings down 12% to 55,782 shares. | SEC filing Filed Jul 30, 2026 |
| Jul 29, 2026 | Planned (10b5-1) | Michael John Isaacs (General Counsel & Company Sec.) sold 8,386 shares at about $8.47 ($71K), marked as a 10b5-1 plan trade. Holdings down 19% to 35,745 shares. | SEC filing Filed Jul 30, 2026 |
| Jun 16, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 20,000 shares at about $7.90 ($158K), reported as a purchase (code P). Holdings up 3% to 756,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 18, 2026 |
| Jun 11, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 125,000 shares at about $8.17 ($1.0M), reported as a purchase (code P). Holdings up 13% to 1,061,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 12, 2026 |
| Jun 4, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 50,000 shares at about $9.31 ($466K), reported as a purchase (code P). Holdings up 6% to 936,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 5, 2026 |
| Jun 2, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 50,000 shares at about $9.43 ($472K), reported as a purchase (code P). Holdings up 6% to 886,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 3, 2026 |
| May 22, 2026 | Purchase (code P) | William P. Scully (10% owner) bought 100,000 shares at about $9.81 ($981K), reported as a purchase (code P). Holdings up 14% to 836,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 26, 2026 |
26 routine transactions (such as grants, option exercises or tax withholding) are not listed.
Cluster buys
No cluster buys in the last 12 months.
Red flags
No red flags in the last 12 months.
Key events
No key events in the last 12 months.
8-K filings, last 12 months
No 8-K filings in the last 12 months.
Red flags are objective triggers only: the item or form filed, never an opinion.
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