Prothena Corporation plc (PRTA) · Insider trading
What Prothena's directors, officers and largest holders bought and sold themselves, from the Form 4 each of them files with the SEC within two business days of a trade. Open-market purchases and sales first: those are the trades somebody chose to make at the market price.
Bought, 12 months
$9.93M
1 insider, 15 trades
Sold, 12 months
$135,927
2 insiders, 100% under a plan
Net, 12 months
+$9.80M
bought less sold
Latest filing
2026-10-09
filings read to 2026-10-19
Who traded, two years
| Insider | Bought | Sold | Trades | Last trade | Holds after |
|---|---|---|---|---|---|
| EcoR1 Capital, LLC10% owner | – | $50.83M | 3 | 2025-05-06 | – |
| Scully William P10% owner | $12.68M | – | 21 | 2026-10-08 | – |
| Isaacs Michael JohnGeneral Counsel & Company Sec. | – | $71,029 | 1 | 2026-07-29 | 35,745 |
| Kingston Anne EvansChief Strategy Officer | – | $64,897 | 1 | 2026-07-29 | 55,782 |
Open-market purchases and sales
Newest first. “Plan” marks a trade made under a 10b5-1 plan set up in advance.
| Date | Insider | Trade | Shares | Price | Value | Holds after | Filing |
|---|---|---|---|---|---|---|---|
| 2026-10-08 | Scully William P10% owner | Buyindirect | 90,000 | 8.57 | $770,904 | 529,000 | Form 4 |
| 2026-10-07 | Scully William P10% owner | Buyindirect | 125,000 | 8.40 | $1.05M | 439,000 | Form 4 |
| 2026-10-02 | Scully William P10% owner | Buyindirect | 100,000 | 8.57 | $857,240 | 314,000 | Form 4 |
| 2026-09-29 | Scully William P10% owner | Buyindirect | 162,000 | 8.68 | $1.41M | 214,000 | Form 4 |
| 2026-09-28 | Scully William P10% owner | Buyindirect | 103,500 | 8.60 | $890,100 | 187,000 | Form 4 |
| 2026-09-18 | Scully William P10% owner | Buy | 100,000 | 8.43 | $843,000 | 927,000 | Form 4 |
| 2026-09-02 | Scully William P10% owner | Buy | 27,000 | 9.47 | $255,690 | 827,000 | Form 4 |
| 2026-08-20 | Scully William P10% owner | Buy | 50,000 | 8.79 | $439,500 | 800,000 | Form 4 |
| 2026-08-07 | Scully William P10% owner | Buy | 34,000 | 8.62 | $293,080 | 790,000 | Form 4 |
| 2026-08-07 | Scully William P10% owner | Buyindirect | 3,500 | 8.62 | $30,170 | 83,500 | Form 4 |
| 2026-07-29 | Isaacs Michael JohnGeneral Counsel & Company Sec. | Saleplan | 8,386 | 8.47 | $71,029 | 35,745 | Form 4 |
| 2026-07-29 | Kingston Anne EvansChief Strategy Officer | Saleplan | 7,662 | 8.47 | $64,897 | 55,782 | Form 4 |
| 2026-06-16 | Scully William P10% owner | Buy | 20,000 | 7.90 | $158,000 | 756,000 | Form 4 |
| 2026-06-11 | Scully William P10% owner | Buy | 125,000 | 8.17 | $1.02M | 1,061,000 | Form 4 |
| 2026-06-04 | Scully William P10% owner | Buy | 50,000 | 9.31 | $465,500 | 936,000 | Form 4 |
| 2026-06-02 | Scully William P10% owner | Buy | 50,000 | 9.43 | $471,500 | 886,000 | Form 4 |
| 2026-05-22 | Scully William P10% owner | Buy | 100,000 | 9.81 | $981,000 | 836,000 | Form 4 |
| 2025-05-06 | EcoR1 Capital, LLC10% owner | Saleindirect | 1,984,053 | 7.64 | $15.16M | 5,304,596 | Form 4 |
| 2025-05-05 | EcoR1 Capital, LLC10% owner | Saleindirect | 977,693 | 8.11 | $7.93M | 7,288,649 | Form 4 |
| 2025-05-02 | EcoR1 Capital, LLC10% owner | Saleindirect | 3,317,938 | 8.36 | $27.74M | 8,266,342 | Form 4 |
| 2025-01-14 | Scully William P10% owner | Buy | 100,000 | 12.79 | $1.28M | 735,993 | Form 4 |
| 2024-12-31 | Scully William P10% owner | Buy | 1,200 | 13.37 | $16,044 | 619,393 | Form 4 |
| 2024-12-31 | Scully William P10% owner | Buy | 800 | 13.39 | $10,712 | 620,193 | Form 4 |
| 2024-12-31 | Scully William P10% owner | Buy | 30,000 | 12.99 | $389,700 | 650,193 | Form 4 |
| 2024-12-20 | Scully William P10% owner | Buy | 2,000 | 15.91 | $31,820 | 618,693 | Form 4 |
| 2024-12-18 | Scully William P10% owner | Buy | 73,436 | 13.93 | $1.02M | 1,297,693 | Form 4 |
Grants, exercises and other transactions
Pay, tax and paperwork rather than a choice to trade at the market price. Two years.
11 × gift7 × grant or award6 × option exercise6 × returned to the company3 × shares withheld for tax
Show them
| Date | Insider | What | Shares | Price | Holds after | Filing |
|---|---|---|---|---|---|---|
| 2026-08-18 | Scully William P10% owner | Gift G | −627,553 | – | 750,000 | Form 4 |
| 2026-08-17 | Scully William P10% owner | Gift G | +336,000 | – | 1,377,553 | Form 4 |
| 2026-08-10 | Scully William P10% owner | Gift G | +251,553 | – | 1,041,553 | Form 4 |
| 2026-07-28 | Isaacs Michael JohnGeneral Counsel & Company Sec. | Shares withheld for tax F | −4,694 | 8.56 | 44,131 | Form 4 |
| 2026-07-28 | Kingston Anne EvansChief Strategy Officer | Shares withheld for tax F | −3,498 | 8.56 | 63,444 | Form 4 |
| 2026-07-28 | Kinney Gene G.Director, President and CEO | Option exercise M | +84,000 | – | 152,793 | Form 4 |
| 2026-07-28 | Kinney Gene G.Director, President and CEO | Returned to the company D | −84,000 | 8.56 | 68,793 | Form 4 |
| 2026-07-28 | Nguyen TranChief Strategy Officer and CFO | Option exercise M | +57,000 | – | 97,205 | Form 4 |
| 2026-07-28 | Nguyen TranChief Strategy Officer and CFO | Returned to the company D | −57,000 | 8.56 | 40,205 | Form 4 |
| 2026-07-28 | Smith Brandon S.Chief Operating Officer | Option exercise M | +78,000 | – | 130,000 | Form 4 |
| 2026-07-28 | Smith Brandon S.Chief Operating Officer | Returned to the company D | −78,000 | 8.56 | 52,000 | Form 4 |
| 2026-07-28 | Swanson Chad J.Chief Development Officer | Option exercise M | +51,000 | – | 85,000 | Form 4 |
| 2026-07-28 | Swanson Chad J.Chief Development Officer | Returned to the company D | −40,800 | 8.56 | 44,200 | Form 4 |
| 2026-07-28 | Swanson Chad J.Chief Development Officer | Shares withheld for tax F | −3,467 | 8.56 | 40,733 | Form 4 |
| 2026-07-28 | Walker Karin LChief Accounting Officer | Option exercise M | +15,000 | – | 25,000 | Form 4 |
| 2026-07-28 | Walker Karin LChief Accounting Officer | Returned to the company D | −15,000 | 8.56 | 10,000 | Form 4 |
| 2026-07-28 | Zago Wagner M.Chief Scientific Officer | Option exercise M | +51,000 | – | 85,000 | Form 4 |
| 2026-07-28 | Zago Wagner M.Chief Scientific Officer | Returned to the company D | −51,000 | 8.56 | 34,000 | Form 4 |
| 2026-06-15 | Scully William P10% owner | Gift G | −325,000 | – | 736,000 | Form 4 |
| 2025-07-28 | Kinney Gene G.Director, President and CEO | Grant or award A | +140,000 | – | 152,793 | Form 4 |
| 2025-07-28 | Malecek Michael JChief Legal Officer | Grant or award A | +80,000 | – | 80,000 | Form 4 |
| 2025-07-28 | Nguyen TranChief Strategy Officer and CFO | Grant or award A | +95,000 | – | 97,205 | Form 4 |
| 2025-07-28 | Smith Brandon S.Chief Operating Officer | Grant or award A | +130,000 | – | 130,000 | Form 4 |
| 2025-07-28 | Swanson Chad J.Chief Development Officer | Grant or award A | +85,000 | – | 85,000 | Form 4 |
| 2025-07-28 | Walker Karin LChief Accounting Officer | Grant or award A | +25,000 | – | 25,000 | Form 4 |
| 2025-07-28 | Zago Wagner M.Chief Scientific Officer | Grant or award A | +85,000 | – | 85,000 | Form 4 |
| 2025-01-15 | Scully William P10% owner | Gift G | −12,000 | – | 47,000 | Form 4 |
| 2025-01-03 | Scully William P10% owner | Gift G | −1,000 | – | 635,993 | Form 4 |
| 2025-01-02 | Scully William P10% owner | Gift G | −13,200 | – | 636,993 | Form 4 |
| 2024-12-20 | Scully William P10% owner | Gift G | −500 | – | 618,193 | Form 4 |
| 2024-12-20 | Scully William P10% owner | Gift G | −40,000 | – | 59,000 | Form 4 |
| 2024-12-19 | Scully William P10% owner | Gift G | −681,000 | – | 616,693 | Form 4 |
| 2024-12-18 | Scully William P10% owner | Gift G | +430,000 | – | 1,224,257 | Form 4 |
How to read it
- Buy, sale
- Code P and S on the form: shares bought or sold in the market, at the market price. The other codes are mostly pay (a grant, an option exercised) or tax (shares the company withheld), and say little about what the insider thinks of the price.
- Plan
- A sale or purchase under a Rule 10b5-1 plan, set up in advance and running on its own schedule. Since April 2023 the form has a box for it. Much executive selling is planned and says more about diversifying than about the company.
- Holds after
- The shares the insider still held after the trade, in the form the trade was in (directly, or indirectly through a trust or a fund).
- Value
- Shares times the price the form reports, which is often an average over several fills on the day.
Read from the SEC's own quarterly data sets of Forms 3, 4 and 5, and from each day's filings since the last one. A correcting amendment replaces the lines it restates. Every row links to its filing. None of this is advice: insiders sell for many reasons, and buy for fewer.