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PRTAProthena Corporation plcSell5.2·$9.69+1.15%
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Prothena Corporation plc (PRTA) Stock Analysis

Inst Constrain edge

SellModerate Confidence

Healthcare · Biotechnology

Sell if holding. Engine safety override at $9.69: Quality below floor (3.2 < 4.0) triggers a hard block regardless of the otherwise-positive setup — overall score 5.2/10 and A.R:R 6.1:1 is above the 1.5:1 BUY gate. Specifically: High short interest: 18%; Below-average business quality; Below long-term trend.

Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation. Its product pipeline includes Prasinezumab, an investigational humanized monoclonal antibody which is... Read more

$9.69+92.2% A.UpsideScore 5.2/10#97 of 258 Biotechnology
QualityF-score3 / 9FCF yield-6.23%
Stop $9.01Target $18.62(analyst − 13%)A.R:R 6.1:1
Analyst target$21.40+120.8%5 analysts
$18.62our TP
$9.69price
$21.40mean
$36

Sell if holding. Engine safety override at $9.69: Quality below floor (3.2 < 4.0) triggers a hard block regardless of the otherwise-positive setup — overall score 5.2/10 and A.R:R 6.1:1 is above the 1.5:1 BUY gate. Specifically: High short interest: 18%; Below-average business quality; Below long-term trend. Chart setup: No clear chart pattern; technical signals are mixed. Score 5.2/10, moderate confidence.

Passes 7/8 gates (favorable risk/reward ratio, clean insider activity, no SEC red flags, news events none recent, earnings proximity 30d clear, semi cycle peak clear, materials cycle peak clear). Fails on weak momentum. Suitability: speculative.

TrendMatrix Research · upcoming catalyst calendar

Upcoming dated catalysts

Mon, Aug 3, 202630d to earnings· next earnings call

Thesis

Rewards
No bull case signals
Risks
Quality below floor (3.2 < 4.0)

Key Metrics

P/E (TTM)
P/E (Fwd)-7.4
Mkt Cap$507M
EV/EBITDA-2.0
Profit Mgn-260.9%
ROE-40.3%
Rev Growth1706.4%
Beta-0.31
DividendNone
Rating analysts12

Quality Signals

Piotroski F3/9

Options Flow

P/C0.67bullish
IV102%elevated

Model-generated analysis — not investment advice. Not a registered investment advisor. Past performance does not guarantee future results.

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Methodology · Editorial policy & full disclaimer

Rating Breakdown

3 floor-breakers

Volatile — 5.3% daily ATR makes tight stops impractical. Position-size conservatively.static

Days To Cover
0.0
Volatility
0.0
Implied Vol
0.0
Short Interest
1.7
Debt Equity
2.6
Put Call
8.9
High short interest justified: 18%High IV: 102%

Clinical-stage biotech: losses expected pre-commercialisation. Quality floor doesn't distinguish R&D investment from operational decay — components above tell the real story.static

Roe
0.0
Roa
0.0
Fcf Quality
0.0
Piotroski F
3.3
Moat
4.2
Current Ratio
5.0
Operating Margin
10.0
Cash-burning: FCF -55% of revenueNo competitive moatWeak Piotroski F-Score: 3/9

Technicals below the gate floor. Component breakdown shows what dragged the score down.static

Support Resistance
1.9
Bollinger
2.3
52w Position
6.4
GatesMomentum 4.0<4.5A.R:R 6.1 ≥ 1.5Insider activity: OKNo SEC red flagsNEWS EVENTS NONE RECENTEARNINGS PROXIMITY 30d clearSEMI CYCLE PEAK CLEARMATERIALS CYCLE PEAK CLEARSuitability: Speculative
RSI
73 · Overbought
20D MA 50D MA 200D MAGOLDEN CROSSSupport $7.73Resistance $10.15

Price Targets

$9
$19
A.Upside+92.2%
A.R:R6.1:1

Position Sizing

ConvictionNone
Suggested %0.5%
Max %1%
RegimeSteady

Risk Alerts

! Quality below floor (3.2 < 4.0)
! momentum at 4.0 (below the engine's 4.5 threshold)

Earnings

B
B
M
M
2/4 beats
Next Earnings2026-08-03 (30d)

Verdict History

reverse chrono — latest first
Loading history...
Verdicts are recorded on every nightly pipeline run. Rows capture transitions (verdict flips, score deltas ≥0.3, entry/TP/SL changes). Rows with a ▶ can be expanded to see the change reason. Aggregate cohort performance is tracked in the recommendation ledger.
Frequently Asked Questions
Is PRTA stock a buy right now?

Sell if holding. Engine safety override at $9.69: Quality below floor (3.2 < 4.0) triggers a hard block regardless of the otherwise-positive setup — overall score 5.2/10 and A.R:R 6.1:1 is above the 1.5:1 BUY gate. Specifically: High short interest: 18%; Below-average business quality; Below long-term trend. Chart setup: No clear chart pattern; technical signals are mixed. Prior stop was $9.01. Score 5.2/10, moderate confidence.

What is the PRTA stock price target?

Take-profit target: $18.62 (+92.2% upside). Prior stop was $9.01. Stop-loss: $9.01.

What are the risks of investing in PRTA?

Quality below floor (3.2 < 4.0).

Is PRTA overvalued or undervalued?

Prothena Corporation plc trades at a P/E of N/A (forward -7.4). TrendMatrix value score: 7.1/10. Verdict: Sell.

What do analysts say about PRTA?

12 analysts cover PRTA with a consensus score of 3.8/5. Average price target: $21.

What does Prothena Corporation plc do?Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel...

Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation. Its product pipeline includes Prasinezumab, an investigational humanized monoclonal antibody which is in Phase 3 clinical trial for the treatment of parkinson's disease and other synucleinopathies. The company also develops Coramitug, an investigational antibody, which is in Phase 3 clinical trial for the treatment of transthyretin amyloidosis; BMS-986446, an anti-tau antibody which is in Phase 2 clinical trial to treat Alzheimer's disease; PRX019, an investigational antibody which is in Phase 1 clinical trial for the treatment of neurodegenerative diseases; and PRX123, a Dual Aß-Tau Vaccine, which is in preclinical trial for treating Alzheimer's disease. In addition, it develops discovery- and late-preclinical-stage programs include TDP-43 CYTOPE for the treatment of amyotrophic lateral sclerosis; PRX012, a next-generation anti-Aß antibody which is in phase 1 clinical trial to treat Alzheimer's disease; and PRX012-TfR, a preclinical program for the treatment of Alzheimer's disease. It has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target a-synuclein, including prasinezumab; and master collaboration agreement with Bristol Myers Squibb to develop and commercialize antibodies targeting tau, TDP-43. Prothena Corporation plc was incorporated in 2012 and is based in Dublin, Ireland.

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