Market Cap
$442.3M
PRTA
PROTHENA CORP PUBLIC LTD CO
$8.44 ▼ -1.17%
Prev close $8.54Market cap$442.3M
12-mo target$21.40 (+153.9%)
Insider Buying Cluster (3 insiders)High Impact Filing (8/10) Biotech & Drug Discovery
Snapshot
The big-picture read on PRTA right now — valuation, ownership and activity at a glance.
Cap Size
Small Cap
Insider Activity
$7.3M buy / $136.0K sell
Insider Net $
$7.1M
SEC Reports
10
Price chart 30d -12.9%
Daily candles (open–high–low–close) with volume. Green = up day, red = down day.
No data for this timeframe.
Vol
Recent activity
The latest filings, insider trades, analyst actions, press and options flow — newest first.
Sep 29, 2026 Insider
SCULLY WILLIAM P bought 162,000 shares
10%+ Owner @ $8.68 ($1.4M)
Sep 28, 2026 Insider
SCULLY WILLIAM P bought 103,500 shares
10%+ Owner @ $8.60 ($889.9K)
Sep 18, 2026 Insider
Sep 3, 2026 SEC SCULLY WILLIAM P bought 100,000 shares
10%+ Owner @ $8.43 ($843.5K)
William P. Scully, a 10% owner of Prothena, purchased 27,000 shares on the open market for approximately $256K at $9.47/
INSIDER-BUY — Impact 3/10
10% owner William Scully made a $439K open-market purchase of PRTA shares at $8.79, adding to his position after gifting
INSIDER-BUY — Impact 4/10
William P. Scully, a 10% owner of Prothena, made a single-day open-market purchase of 37,500 shares for $323K on August
INSIDER-BUY — Impact 5/10
Aug 6, 2026 earnings_calendar
PRTA Q2 2026 Earnings Scheduled — 2026-08-06
Analyst ratings buy % -2.9%
How Wall Street rates the stock today, and the latest firm-by-firm actions.
Recent analyst actions
| Date | Firm | Action | Rating | Firm rating |
|---|---|---|---|---|
| May 8, 2026 | Citizens | MAINTAIN | Market Outperform | 38% |
Monthly consensus history
| Period | Str. Buy | Buy | Hold | Sell | Str. Sell | Buy % | Distribution |
|---|---|---|---|---|---|---|---|
| Sep 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| Aug 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| Jul 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| Jun 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| May 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| Apr 1, 2026 | 2 | 6 | 3 | 1 | 0 | 67% | |
| Mar 1, 2026 | 2 | 7 | 3 | 1 | 0 | 69% | |
| Feb 1, 2026 | 2 | 7 | 3 | 1 | 0 | 69% |
Price targets
Where 5 covering analysts think PRTA trades over the next 12 months.
$21.40 +153.9% upside Strong Buy
Current$8.43 Low$8.00 Median$20.00 High$36.00 5 analysts
$8.00$36.00
Analyst rating None as of Oct 2, 2026
Reports & filings
AI-scored summaries of recent SEC filings and press releases, with sentiment and impact.
10 SEC filing reports analyzed · 5 bullish, 0 bearish, 0 mixed, 5 neutral · avg impact 4.0/10.
NEUTRALINSIDER-BUY3/10
William P. Scully, a 10% owner of Prothena, purchased 27,000 shares on the open market for approxima
Sep 3, 2026
BULLISHINSIDER-BUY4/10
10% owner William Scully made a $439K open-market purchase of PRTA shares at $8.79, adding to his po
Aug 21, 2026
BULLISHINSIDER-BUY5/10
William P. Scully, a 10% owner of Prothena, made a single-day open-market purchase of 37,500 shares
Aug 10, 2026
NEUTRALCLUSTER2/10
Two C-suite insiders at Prothena (PRTA) sold a combined $136K in open-market sales on July 29, 2026,
Jul 31, 2026
Upcoming & catalyst events
Scheduled dates plus disclosed catalysts — earnings, dividends, enforcement, FDA and clinical-trial events. Colored dot = impact.
Aug 6, 2026
earnings_calendar
PRTA Q2 2026 Earnings Scheduled — 2026-08-06
Aug 3, 2026
earnings_calendar
PRTA Q2 2026 Earnings Scheduled — 2026-08-03
May 13, 2026
earnings_calendar
PRTA Q1 2026 Earnings Scheduled — 2026-05-13
May 7, 2026
earnings_calendar
PRTA Q1 2026 Earnings Scheduled — 2026-05-07
Earnings estimates
Forecast earnings per share and revenue by period — and whether estimates are rising.
| Period | EPS Est. | Range | Growth | 30d Rev | Up/Dn | Revenue | # |
|---|---|---|---|---|---|---|---|
| Current Q | $-0.38 | $-0.38–$-0.38 | 43.3% | -1.3% | 1↑ 0↓ | $0.0B | 1 |
| Next Q | $0.74 | $0.74–$0.74 | 262.0% | +244.2% | 1↑ 0↓ | $0.0B | 1 |
| Current FY | $0.65 | $0.65–$0.65 | 116.3% | +1.6% | 2↑ 0↓ | $0.1B | 1 |
| Next FY | $-1.52 | $-1.52–$-1.52 | -333.8% | -16.0% | 1↑ 0↓ | $0.0B | 1 |
Current-quarter EPS estimate — revision history
| When | EPS estimate | Change vs now |
|---|---|---|
| Current | $-0.380 | — |
| 7d ago | $-0.375 | -0.005 |
| 30d ago | $-0.375 | -0.005 |
| 60d ago | $-0.375 | -0.005 |
| 90d ago | $-0.375 | -0.005 |
Insider activity
Buying and selling by company executives and directors (SEC Form 4).
16 insiders, 47 transactions. Net $7.1M — $7.3M bought, $136.0K sold.
| Date | Insider | Title | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Sep 29, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 162,000 | $8.68 | $1.4M |
| Sep 28, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 103,500 | $8.60 | $889.9K |
| Sep 18, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 100,000 | $8.43 | $843.5K |
| Sep 2, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 27,000 | $9.47 | $255.7K |
| Aug 20, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 50,000 | $8.79 | $439.4K |
| Aug 18, 2026 | SCULLY WILLIAM P | 10%+ Owner | GIFT | 627,553 | — | — |
| Aug 17, 2026 | SCULLY WILLIAM P | 10%+ Owner | GIFT | 336,000 | — | — |
| Aug 10, 2026 | SCULLY WILLIAM P | 10%+ Owner | GIFT | 251,553 | — | — |
| Aug 7, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 34,000 | $8.62 | $293.1K |
| Aug 7, 2026 | SCULLY WILLIAM P | 10%+ Owner | BUY | 3,500 | $8.62 | $30.2K |
Short interest & halts
FINRA semi-monthly short positions, Reg SHO threshold status, and recent trading halts for PRTA.
Shares short
8,544,664
Settlement Sep 15, 2026
Change vs prior
+0.6%
Semi-monthly cycle
Days to cover
26.5
At avg daily volume
Of shares outstanding
≈16.6%
Estimate — not % of float
All PRTA filing & press-release reports (10)
- INSIDER-BUY reportSep 3, 2026
- INSIDER-BUY reportAug 21, 2026
- INSIDER-BUY reportAug 10, 2026
- CLUSTER reportJul 31, 2026
- INSIDER-BUY reportJun 18, 2026
- INSIDER-BUY reportJun 12, 2026
- 3 reportMay 14, 2026
- 8-K reportMay 7, 2026
- DEFA14A reportMar 27, 2026
- EFFECT reportMar 3, 2026