SEC Form 4
Prothena Corporation plc (PRTA) insider trading
In the 12 months to Oct 23, 2026, 2 PRTA insiders reported open-market sales of $136.0K across 2 filings; one 10% owner bought $10.9M.
Latest filing · Last 12 months · Source: SEC EDGAR · How we count
- Open-market sales
- $136.0K
- 2 filings · 2 insiders
- Open-market purchases
- $10.9M
- 14 filings · William P. Scully, 10% owner
- Pre-arranged sales (10b5-1)
- 2 of 2
- All $136.0K sold was pre-arranged
Who traded PRTA, and when
- Purchase
- Sale
- Sale, pre-arranged (10b5-1)
PRTA daily close from Oct 23, 2025 to Oct 23, 2026, between $7.91 and $11.51, last $8.20. 2 sale and 14 purchase filings by 3 insiders, marked at their filing dates. William P. Scully, 10% owner: bought $10.9M across 14 filings, first filed May 26, 2026, last Oct 15, 2026. Michael John Isaacs, General Counsel & Company Sec.: sold $71.1K across 1 filing, first filed Jul 30, 2026, last Jul 30, 2026. Anne Evans Kingston, Chief Strategy Officer: sold $64.9K across 1 filing, first filed Jul 30, 2026, last Jul 30, 2026.
Largest mark · tap a row for others
William P. Scully · 10% owner
Filing 1 of 2 within a week · $2,678,294 total
Purchase $857,240
100,000 shares
Filed Oct 6, 2026 · traded Oct 2
Close on filing date $8.02
William P. Scully · 10% owner
10% owner
$10.9M boughtMichael John Isaacs · General Counsel & Company Sec.
General Counsel & Company Sec.
$71.1K soldAnne Evans Kingston · Chief Strategy Officer
Chief Strategy Officer
$64.9K soldHas Prothena Corporation plc's CEO sold stock?
No. Gene G. Kinney (CEO) made no open-market sales filed as CEO in the last 12 months.
Open-market trades
16 filings in the last 12 months| Insider | Role | Sold | Bought | Filings | Pre-arranged (10b5-1) | Last filed |
|---|---|---|---|---|---|---|
| William P. Scully | 10% owner | — | $10.9M | 14 | — | |
| Michael John Isaacs | General Counsel & Company Sec. | $71.1K | — | 1 | 100% of sales | |
| Anne Evans Kingston | Chief Strategy Officer | $64.9K | — | 1 | 100% of sales |
| Filed | Insider | Type | Shares | Value | Held after | Source |
|---|---|---|---|---|---|---|
traded | William P. Scully 10% owner | Purchase | 110,000 ordinary shares | $920.0K | 1,037,000 | |
traded | William P. Scully 10% owner | Purchase | 215,000 ordinary shares | $1.8M | 529,000 | |
traded | William P. Scully 10% owner | Purchase | 100,000 ordinary shares | $857.2K | 314,000 | |
traded | William P. Scully 10% owner | Purchase | 162,000 ordinary shares | $1.4M | 214,000 | |
traded | William P. Scully 10% owner | Purchase | 103,500 ordinary shares | $889.9K | 187,000 | |
traded | William P. Scully 10% owner | Purchase | 100,000 ordinary shares | $843.5K | 927,000 | |
traded | William P. Scully 10% owner | Purchase | 27,000 ordinary shares | $255.7K | 827,000 | |
traded | William P. Scully 10% owner | Purchase | 50,000 ordinary shares | $439.4K | 800,000 | |
traded | William P. Scully 10% owner | Purchase | 37,500 ordinary shares | $323.2K | Multiple accounts | |
traded | Michael John Isaacs General Counsel & Company Sec. | SalePre-arranged (10b5-1) | 8,386 ordinary shares | $71.1K | 35,745 | |
traded | Anne Evans Kingston Chief Strategy Officer | SalePre-arranged (10b5-1) | 7,662 ordinary shares | $64.9K | 55,782 | |
traded | William P. Scully 10% owner | Purchase | 20,000 ordinary shares | $158.0K | 756,000 | |
traded | William P. Scully 10% owner | Purchase | 125,000 ordinary shares | $1.0M | 1,061,000 | |
traded | William P. Scully 10% owner | Purchase | 50,000 ordinary shares | $465.3K | 936,000 | |
traded | William P. Scully 10% owner | Purchase | 50,000 ordinary shares | $471.3K | 886,000 | |
traded | William P. Scully 10% owner | Purchase | 100,000 ordinary shares | $981.3K | 836,000 |
Shares are as filed (ordinary shares or ADS); values are as converted to US$ in the filing.
GET /stocks/filings/vX/form-4?tickers=PRTA&filing_date.gte=2025-10-23&sort=filing_date.desc&limit=500{
"status": "OK",
"results": [
{
"tickers": [
"PRTA"
],
"issuer_cik": "0001559053",
"owner_cik": "0001045463",
"accession_number": "0001045463-26-000021",
"form_type": "4",
"filing_date": "2026-10-15",
"period_of_report": "2026-10-13",
"issuer_name": "PROTHENA CORP PUBLIC LTD CO",
"issuer_trading_symbol": "PRTA",
"owner_name": "SCULLY WILLIAM P",
"is_director": false,
"is_officer": false,
"is_ten_percent_owner": true,
"is_other": false,
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Ordinary Shares, par value $0.01 per share",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-10-14",
"transaction_code": "P",
"equity_swap_involved": false,
"transaction_shares": 10000,
"transaction_price_per_share": 8.4569,
"transaction_acquired_disposed": "A",
"shares_owned_following_transaction": 1037000,
"transaction_value": 84568.99999999999,
"not_subject_to_section_16": false,
"direct_or_indirect": "D",
"footnotes": [
{
"id": "F2",
"description": "The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.4000 to $8.5600, inclusive."
}
]
},
{
"tickers": [
"PRTA"
],
"issuer_cik": "0001559053",
"owner_cik": "0001045463",
"accession_number": "0001045463-26-000021",
"form_type": "4",
"filing_date": "2026-10-15",
"period_of_report": "2026-10-13",
"issuer_name": "PROTHENA CORP PUBLIC LTD CO",
"issuer_trading_symbol": "PRTA",
"owner_name": "SCULLY WILLIAM P",
"is_director": false,
"is_officer": false,
"is_ten_percent_owner": true,
"is_other": false,
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Ordinary Shares, par value $0.01 per share",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-10-13",
"transaction_code": "P",
"equity_swap_involved": false,
"transaction_shares": 100000,
"transaction_price_per_share": 8.3548,
"transaction_acquired_disposed": "A",
"shares_owned_following_transaction": 1027000,
"transaction_value": 835479.9999999999,
"not_subject_to_section_16": false,
"direct_or_indirect": "D",
"footnotes": [
{
"id": "F1",
"description": "The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.2547 to $8.4616, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (1) and (2) to this Form 4."
}
]
}
]
}
// trimmed to 2 resultsThe response includes every Form 4 record; this page keeps open-market purchases and sales on common stock and removes duplicate joint-filer rows.
Other insider activity (not market trades) · 19 records
- Option exercises6 records
- Tax withholding3 records
- Gifts4 records
- Other6 records
Reported on Form 4 but not purchases or sales in the market, so not counted in the totals above.
Build this yourself
This page joins two Massive endpoints: Form 4 filings and daily prices. Ask an agent to watch for new filings:
Using the Massive API (massive.com/docs/llms.txt), check Form 4 filings for PRTA every day with transaction_code=P and tell me when an insider files an open-market purchase, with their role, shares, price and the filing link.
How to read this page
- Open-market purchase or sale
- A buy or sell of the company's stock at market price. Grants, option exercises, shares withheld for tax, gifts and employee stock plan purchases are listed separately and not counted.
- Pre-arranged (10b5-1)
- The insider marked the filing as made under a trading plan set up in advance (SEC Rule 10b5-1). The mark covers the whole filing, and an unmarked filing may still be under a plan.
- Filing date
- Insiders have two business days to report a trade. Totals and the chart use the filing date, when the trade became public.