Insider Buy ·Filed Sep 29, 2026
Insider cluster: 1 insiders, $890K total
Actionable Insight ▲ Bullish
Monitor for any upcoming corporate announcements (e.g., pipeline updates, partnership news) that may have motivated this insider purchase. The size and nature of the buy suggest confidence in near-term value.
Latest settled — T+5d
PRTA ▲ +1.19% at T+5d
LONG call ✓ call won +1.19% · α vs SPY -0.72% · entry $8.38 → $8.48
Latest observation: T+17 -0.89% FF3 residual α
T+1d
+1.91%
call +1.91% · α +1.73%
$8.54
settled 26d ago
T+5d
+1.19%
call +1.19% · α -0.72%
$8.48
settled 20d ago
T+20d
Pending
in 20h
T+60d
Pending
in 8w
Price Chart
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Executive Summary
10% owner William P. Scully purchased 103,500 shares of Prothena Corp for $890K at $8.60 per share on September 28, 2026. This is a substantial open-market buy by a major insider, representing a significant personal investment and a bullish signal for the stock.
Key Financial Metrics
Direction
buying
Total Value
$890.0K
Insiders
1
Key Facts
- 10% owner William P. Scully purchased 103,500 shares at $8.60 per share on September 28, 2026.
- Total purchase value: $890,000.
- This is an open-market purchase (SEC Form 4, code P) by a 10% owner, a recognized standalone bullish signal.
Financial Impact
$890,000 open-market purchase by a 10% owner.
insider ownershipmarket sentiment
Risk Factors
- Insider buys do not guarantee short-term price appreciation; the stock may still decline.
Investment Themes
Documents Analyzed
This report is based on 1 SEC document filed with EDGAR.
| Document | Accession Number |
|---|---|
| INSIDER-BUY Data (Synthetic) | 0001045463-26-000017 |
14 reports for PRTA
50% Hit rate @ T+1 Went positive at some point 5 of 8 best @ T+60▲ +14.11%
Filters
Rows
| Type | Now | ||||
|---|---|---|---|---|---|
Oct 15, 2026 10d ago | Insider Buy | $8.35 $8.48 | ▲ +1.56% | ▲ +1.13% | $8.41 (+0.72%) |
Sep 30, 2026 25d ago | Insider Buy | $8.54 $8.36 | ▼ −2.11% | ▼ −2.85% | $8.41 (−1.52%) |
Sep 29, 2026 26d ago | Insider Buy | $8.38 $8.54 | ▲ +1.91% | ▲ +1.73% | $8.41 (+0.36%) |
Sep 21, 2026 5w ago | Insider Buy | $8.99 $8.68 | ▼ −3.45% | ▼ −2.73% | $8.41 (−6.45%) |
Sep 3, 2026 7w ago | Insider Buy | $9.82 $9.54 | ▼ −2.85% | ▼ −2.30% | $8.41 (−14.36%) |
Aug 21, 2026 9w ago | Insider Buy | $9.45 $9.39 | ▼ −0.63% | ▼ −0.34% | $8.41 (−11.01%) |
Aug 10, 2026 10w ago | Insider Buy | $9.12 $9.22 | ▲ +1.10% | ▲ +1.42% | $8.41 (−7.79%) |
Jul 30, 2026 12w ago | Insider Cluster | $8.12 $8.33 | ▲ +2.59% | ▲ +1.16% | $8.41 (+3.57%) |
Jun 18, 2026 18w ago | Insider Buy | $8.93 $9.15 | ▲ +2.46% | ▲ +2.78% | $8.41 (−5.82%) |
Jun 12, 2026 19w ago | Insider Buy | $8.15 $8.29 | ▲ +1.72% | ▲ +2.31% | $8.41 (+3.19%) |
Showing 10 of 14
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