PROTHENA CORP PUBLIC LTD CO (PRTA) insider trading
PROTHENA CORP PUBLIC LTD CO insiders have made 7 open-market purchases worth $8.0M since Sep 21, 2026, by 1 insider. The latest: William P. Scully (10% owner) bought $1.2M, filed Oct 26, 2026, scored 31 out of 100. The biggest: $1.8M by William P. Scully, filed Oct 9, 2026.
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Insider purchases
| Filed | Insider | Stake | Score | Bought | 1 week | 1 month |
|---|---|---|---|---|---|---|
| Oct 26 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +15% stake | 31 | $1.2M 150,000 at $8.15 |
waiting | waiting |
| Oct 15 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +12% stake | 28 | $920k 110,000 at $8.36 |
−1.8% | waiting |
| Oct 9 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +69% stake | 40 | $1.8M 215,000 at $8.47 |
−5.5% | waiting |
| Oct 6 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +47% stake | 33 | $857k 100,000 at $8.57 |
+4.2% | waiting |
| Sep 30 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +312% stake | 40 | $1.4M 162,000 at $8.68 |
+0.8% | waiting |
| Sep 29 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +124% stake | 37 | $890k 103,500 at $8.60 |
+1.2% | +1.1% |
| Sep 21 Form 4 (opens sec.gov) |
William P. Scully10% owner10% owner · Near 52-week low | +12% stake | 28 | $843k 100,000 at $8.43 |
−2.3% | −8.2% |
Track record (hypothetical): a week after the filing, these buys averaged −0.6% (50% up, 6 measured); a month after, −3.6% (50% up, 2 measured).
Insiders who bought PRTA
- William P. Scully 10% owner
Questions
Are insiders buying PRTA stock?
Yes. In the last 90 days, 7 open-market purchases were filed, worth $8.0M.
Who bought PRTA stock most recently?
William P. Scully, 10% owner, bought 150,000 shares for $1.2M (Form 4 (opens sec.gov), filed Oct 26, 2026).
How does InsiderBeacon score an insider buy?
Out of 100, from who bought, how much their stake grew, the size of the trade, whether other insiders bought within ten days, where the price sat in its 52-week range, and whether it was a first or a routine buy. The score is fixed when the filing arrives. The formula and the research behind it.
Insiders are also buying, same industry
Data as of Oct 26, 2026, from SEC EDGAR Form 4 filings: open-market purchases (code P) of $25,000 or more, and open-market sales. Every row links to its filing. Scores summarise what a filing says (how the score works); outcomes are hypothetical, from the first close after the filing, and past results don't predict future ones. Disclaimer