United States · SEC Form 4 · Snapshot date: 2026-10-18 · Built: 2026-10-18 · 中文

US · SEC FORM 4

PROTHENA CORP PUBLIC LTD CO

PRTA · Nasdaq · CIK 0001559053 · Healthcare · Biotechnology

INSIDER SIGNAL

63.2 / 100

1 buyers · 17 purchase transaction lines · $10.9M gross purchase

WHY THIS SIGNAL?

Buyer breadthLow

Purchase sizeStrong

RoleModerate

RecencyStrong

ConvictionStrong

Score anatomy

Each bar shows the contribution to the current score; the weights and formula stay unchanged.

Cluster+7.0 / 35

Purchase size+23.0 / 25

Role+14.0 / 20

Recency+9.4 / 10

Conviction+9.9 / 10

What is holding the score back?

⚠ Cluster breadth is moderate · 1 insider(s), not 4+
⚠ Role scores low · most senior buyer: TenPercentOwner (CEO, chair and 10% owners score lowest)
✓ Recent activity · latest purchase 2026-10-14

Purchase-size comments are relative to the model scale. Average daily volume is a separate market-context diagnostic.

US-v1.2 ranks qualifying equity purchases under the current 180-day rules. The score is a research priority, not a return forecast or probability. Backtests have not shown that a higher US score is followed by better returns.

Insider activity timeline

Owner lanes show the latest 180 days. Symbol shape identifies the transaction type; sales remain context only.

AprMayJunJulAugSepOct

SCULLY WILLIAM PTenPercentOwner

●●●●○●●○○○●●●●●●●●●●

Swanson Chad J.Chief Development Officer

○○○

Kingston Anne EvansChief Strategy Officer

○▼

Isaacs Michael JohnGeneral Counsel & Company Sec.

○▼

Zago Wagner M.Chief Scientific Officer

○○

Walker Karin LChief Accounting Officer

○○

● Purchase▼ Sale○ Other

Showing the six most active owners; 3 additional owner(s) remain in Form 4 evidence.

Purchase breadth & concentration

QUALIFYING BUYERS1

PURCHASE CONCENTRATION100%Largest buyer: SCULLY WILLIAM P · $10.9M

CLUSTER BUYING · 15D1 insiderPeak activity: 2026-05-22–2026-06-04

Roles in the peak window: TenPercentOwner. Concentration uses priced qualifying P lines only and does not change the saved score.

SIGNAL HISTORY

63.2 / 100

Latest recorded score

↓ -0.4 ptsversus the previous recorded snapshot

Oct 1362.9
Oct 1462.8
Oct 1562.6
Oct 1663.6
Oct 1863.2

Only scores saved when a full US scoring run completed are shown; gaps are not reconstructed.

Recent Form 4 activity

17Purchases

2Sales

19Other Form 4 lines

25SEC filings · 365 days

BUYING17 qualifying P line(s) · 180 days

SELLING2 sale line(s) · context only

OTHER19 exercise / withholding / award / gift / other lines

10b5-1 / PLANNEDNot detected in parsed evidence

P is an open-market or private purchase. S is a sale. M, F, A and G usually describe exercises, tax withholding, awards and gifts. These categories remain visually separate.

Market context

Market context provides additional background on recent price performance and risk. It does not affect the Insider Signal.

Price performance

1M: -1.3%
3M: -3.7%
6M: -23.4%
12M: -21.7%

Volatility & liquidity

Volatility: 64.3%
Beta: —
Avg daily value: USD 4.1M

Valuation

Market cap: —
P/E: —

Fundamentals

Profit margin: —
ROE: -87.0%
Industry: Biotechnology

Market data

Price data up to: 2026-10-18 · Price source: OpenBB/yfinance; volume from price cache (yfinance) · From SEC filings: ROE · Fiscal year ended: 2025-12-31 · Status: PASS

Short interest

Short interest is external context reported to FINRA by broker-dealers. It does not affect the Insider Signal.

Shares short: 8,010,864
Previous report: 8,544,664
Avg daily volume: 580,885
Days to cover: 13.8

FINRA settlement date: 2026-09-30 · Captured 2026-10-12 · FINRA equity short interest ↗. A share count, published about a week after each of two settlement dates a month; not a percentage of shares outstanding.

Historical equity purchases

Qualifying code P transactions in the local Form 4 history, including purchases outside the current signal window.

Transaction date	Reporting owner	Type	Security	Shares	Avg. price	Approx. value	Source
2026-10-14	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	10,000	USD 8.46	USD 84,569	SEC filing ↗
2026-10-13	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.35	USD 835,480	SEC filing ↗
2026-10-08	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	90,000	USD 8.57	USD 770,904	SEC filing ↗
2026-10-07	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	125,000	USD 8.40	USD 1,050,150	SEC filing ↗
2026-10-02	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.57	USD 857,240	SEC filing ↗
2026-09-29	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	162,000	USD 8.68	USD 1,406,160	SEC filing ↗
2026-09-28	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	103,500	USD 8.60	USD 890,100	SEC filing ↗
2026-09-18	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.43	USD 843,000	SEC filing ↗
2026-09-02	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	27,000	USD 9.47	USD 255,690	SEC filing ↗
2026-08-20	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	50,000	USD 8.79	USD 439,500	SEC filing ↗
2026-08-07	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	37,500	USD 8.62	USD 323,250	SEC filing ↗
2026-06-16	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	20,000	USD 7.90	USD 158,000	SEC filing ↗
2026-06-11	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	125,000	USD 8.17	USD 1,021,250	SEC filing ↗
2026-06-04	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	50,000	USD 9.31	USD 465,500	SEC filing ↗
2026-06-02	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	50,000	USD 9.43	USD 471,500	SEC filing ↗

Form 4 evidence

38 transaction lines in the latest 365-day window; 472 in local history.

Date	Owner	Type	Security	Shares	Avg. price	Approx. value	Source
2026-10-14	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	10,000	USD 8.46	USD 84,569	SEC filing ↗
2026-10-13	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.35	USD 835,480	SEC filing ↗
2026-10-08	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	90,000	USD 8.57	USD 770,904	SEC filing ↗

Show recent Form 4 evidence (30 grouped rows)

Date	Owner	Type	Security	Shares	Avg. price	Approx. value	Source
2026-10-14	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	10,000	USD 8.46	USD 84,569	SEC filing ↗
2026-10-13	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.35	USD 835,480	SEC filing ↗
2026-10-08	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	90,000	USD 8.57	USD 770,904	SEC filing ↗
2026-10-07	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	125,000	USD 8.40	USD 1,050,150	SEC filing ↗
2026-10-02	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.57	USD 857,240	SEC filing ↗
2026-09-29	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	162,000	USD 8.68	USD 1,406,160	SEC filing ↗
2026-09-28	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	103,500	USD 8.60	USD 890,100	SEC filing ↗
2026-09-18	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	100,000	USD 8.43	USD 843,000	SEC filing ↗
2026-09-02	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	27,000	USD 9.47	USD 255,690	SEC filing ↗
2026-08-20	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	50,000	USD 8.79	USD 439,500	SEC filing ↗
2026-08-18	SCULLY WILLIAM P	Gift (G)	Ordinary Shares, par value $0.01 per share	627,553	USD 0.00	USD 0	SEC filing ↗
2026-08-17	SCULLY WILLIAM P	Gift (G)	Ordinary Shares, par value $0.01 per share	336,000	USD 0.00	USD 0	SEC filing ↗
2026-08-10	SCULLY WILLIAM P	Gift (G)	Ordinary Shares, par value $0.01 per share	251,553	USD 0.00	USD 0	SEC filing ↗
2026-08-07	SCULLY WILLIAM P	Purchase (P)	Ordinary Shares, par value $0.01 per share	37,500	USD 8.62	USD 323,250	SEC filing ↗
2026-07-29	Kingston Anne Evans	Sale (S)	Ordinary Shares, par value $0.01 per share	7,662	USD 8.47	USD 64,897	SEC filing ↗
2026-07-29	Isaacs Michael John	Sale (S)	Ordinary Shares, par value $0.01 per share	8,386	USD 8.47	USD 71,029	SEC filing ↗
2026-07-28	Zago Wagner M.	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	51,000	USD —	USD —	SEC filing ↗
2026-07-28	Zago Wagner M.	D (D)	Ordinary Shares, par value $0.01 per share	51,000	USD 8.56	USD 436,560	SEC filing ↗
2026-07-28	Walker Karin L	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	15,000	USD —	USD —	SEC filing ↗
2026-07-28	Walker Karin L	D (D)	Ordinary Shares, par value $0.01 per share	15,000	USD 8.56	USD 128,400	SEC filing ↗
2026-07-28	Swanson Chad J.	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	51,000	USD —	USD —	SEC filing ↗
2026-07-28	Swanson Chad J.	Tax withholding (F)	Ordinary Shares, par value $0.01 per share	3,467	USD 8.56	USD 29,678	SEC filing ↗
2026-07-28	Swanson Chad J.	D (D)	Ordinary Shares, par value $0.01 per share	40,800	USD 8.56	USD 349,248	SEC filing ↗
2026-07-28	Smith Brandon S.	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	78,000	USD —	USD —	SEC filing ↗
2026-07-28	Smith Brandon S.	D (D)	Ordinary Shares, par value $0.01 per share	78,000	USD 8.56	USD 667,680	SEC filing ↗
2026-07-28	Nguyen Tran	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	57,000	USD —	USD —	SEC filing ↗
2026-07-28	Nguyen Tran	D (D)	Ordinary Shares, par value $0.01 per share	57,000	USD 8.56	USD 487,920	SEC filing ↗
2026-07-28	Kinney Gene G.	Option exercise / conversion (M)	Ordinary Shares, par value $0.01 per share	84,000	USD —	USD —	SEC filing ↗
2026-07-28	Kinney Gene G.	D (D)	Ordinary Shares, par value $0.01 per share	84,000	USD 8.56	USD 719,040	SEC filing ↗
2026-07-28	Kingston Anne Evans	Tax withholding (F)	Ordinary Shares, par value $0.01 per share	3,498	USD 8.56	USD 29,943	SEC filing ↗

Multiple price lines in one filing are grouped and share-weighted. Price and value are blank when a grouped filing line lacks price evidence.

Snapshot & identity

Snapshot date	2026-10-18
Ranking version	US-v1.2
Data quality	PASS ELIGIBLE · —
Ticker	PRTA
CIK	0001559053
Sector	Healthcare
Industry	Biotechnology Yahoo Finance
SEC SIC	2834 Pharmaceutical Preparations
Exchange	Nasdaq

Data coverage

Local Form 4 history	472 transaction lines from 2020-04-08 to 2026-10-14 34 P purchase lines · 282 S sale lines · 156 other lines
SEC company submissions	Open SEC filings ↗

Local ledger as of 2026-10-18. Mapping status is an audit field and does not erase SEC filing evidence.