Prothena Corporation plc (PRTA) Stock: Price, Forecast & Analyst Target
Prothena Corporation plc (PRTA) — MoonshotScore 28/100 (Weak band), calculated Oct 4, 2026. Price $8.36 (-2.11%), as of the Oct 2, 2026 trading session; market cap $438M.
Educational signal · not a buy or sell recommendation · How to read this
Prothena Corporation plc · PRTA · NASDAQ
Prothena Corporation plc is a late-stage clinical biotechnology company focused on developing novel therapies for life-threatening diseases. Their pipeline targets neurodegenerative diseases like Alzheimer's and Parkinson's, as well as amyloidosis.
Price as of Oct 2, 2026
Key Statistics
MoonshotScore v2 · Prothena Corporation (PRTA)
WeakWhy this rating? Method, drivers & history
Bands for the MoonshotScore: Exceptional 80-100 · Strong 65-79 · Fair 45-64 · Weak below 45.
- Business Quality — Is this a genuinely good business?
- Financial Safety — Could this blow up on me?
- Valuation — Am I paying a fair price?
- Growth Durability — Is the growth real and likely to last?
- Momentum — Is the market already moving on this?
A strong balance sheet, but weak quality and stalling growth. Business Quality: Thin; Financial Safety: Sound; Valuation: Fair; Growth Durability: Shrinking; Momentum: Quiet.
- quarterly revenue $1M (Q2 FY2026, quarter ended Jun 2026)
- EPS beat 4 of 8
- Altman Z 11.39 · Piotroski F 3
Holding back: weak fundamentals, soft growth
Helping: balance-sheet strength
What has the MoonshotScore done over time?
| Recorded | Score | Band |
|---|---|---|
| 28 | Weak | |
| 28 | Weak | |
| 28 | Weak | |
| 28 | Weak | |
| 28 | Weak | |
| 28 | Weak |
The score was 28 in the stored Oct 3, 2026 snapshot and remains 28 in the current publication computed Oct 4, 2026 (0).
Calculation uses the most recent completed US trading session. Live price changes do not update the score immediately.
Computed · Educational signal · not a buy or sell recommendation · How the MoonshotScore is computed →
Price & valuation
| Measure | Value | As of |
|---|---|---|
| Latest provided price | $8.36 | |
| Change on the day | -2.11% | |
| 52-week range | $7.73 – $11.80 | |
| Market capitalisation | $438M | |
| Price / earnings (trailing) | -10.75 | |
| Shares traded on the day | 675.8K |
Price & events
Council Score · weighted blend of 2 available disciplines
Council score for Prothena Corporation (PRTA): Split View
38/100 · DSome lenses disagree with the MoonshotScore. Compare their readings below; each uses a different method.
5-Factor Breakdown
Legends Council
6 lenses, 6 current
AI simulations built from the named investors' published principles. Not affiliated with, endorsed by, or the opinion of these individuals. How these lenses are built
Read on: Oct 5, 2026
Munger's Mindset
Balance Sheet & Valuation · historical
Read on: Sep 10, 2026 · older than the 27 hours refresh window; not a current reading
How to read these bars and different assessments
Council is a separate blend of available disciplines; MoonshotScore above remains the five-pillar research rating.
Bars show each model's ordered assessment on its own scale, not a probability or a comparable investment return. The adjacent words give the assessment; more filled segments indicate a stronger model reading.
One of these lenses reads this company more favourably than the MoonshotScore does: Dalio-style lens. Each lens is a separate scoring function over its own inputs, so a disagreement is a difference of method rather than a correction — the page's answer stays the MoonshotScore above.
On Sep 10, 2026, the Munger lens read the price at that time as undervalued against its own estimate of value.
Readings on this page are from Oct 5, 2026, except a card that shows its own read date.
Watch the PRTA film — every key number, told as a short cinematic story
~2 min · open the film
What is Prothena Corporation (PRTA), and what does it report?
Short answer · as of
A current FMP business description is unavailable; the listing and provider classification below are the available identity facts. Prothena Corporation plc (PRTA) is listed on NASDAQ. It employs 67 people and is led by Gene G. Kinney. In Q2 FY2026 it reported revenue of $1M and net income of -$19M. The market values it at $438M.
What do the latest results show for Prothena Corporation (PRTA)?
Short answer · as of
The most recent reported quarter, Q2 FY2026, carried revenue of $1M. Against analyst estimates the company has EPS beat 4 of 8 reports.
Quarterly income statement — 4 quarters
| Period | Revenue | Net income | EPS |
|---|---|---|---|
| Q2 FY2026 | $1M | -$19M | -$0.36 (diluted) |
| Q1 FY2026 | $51M | $33M | $0.60 (diluted) |
| Q4 FY2025 | $21,000 | -$22M | -$0.40 (diluted) |
| Q3 FY2025 | $2M | -$37M | -$0.68 (diluted) |
What are the financial strengths and risks for Prothena Corporation (PRTA)?
Short answer
The MoonshotScore pillars rate balance-sheet strength as strengths. What is holding it back is weak fundamentals, soft growth. The distress and quality screens read Altman Z 11.39 · Piotroski F 3. Trailing ratios: ROE -15.0% · ROA -14.5% · current ratio 25.05 · earnings yield -10.1% · free-cash-flow yield -13.8%.
Data-derived red flags
- Negative return on equity (-15.0%) — the business is not currently generating profit on shareholder capital.
- Weak fundamentals — a Piotroski F-Score of 3/9 flags soft profitability, leverage or efficiency.
What should you watch next at Prothena Corporation (PRTA)?
Short answer · as of
Current published price targets run low $30.00 · high $30.00 · consensus $30.00 · median $30.00 against a quoted price of $8.36 (as of Oct 2, 2026).
What the records here don't tell us
- No forward revenue or earnings estimate is on file.
- The next earnings date is not yet scheduled in the calendar we read.
Checked against the records this page reads, on the dates shown above.
How does Prothena Corporation compare with its peers?
Short answer
Prothena Corporation's score ranks 13th of 13 in the bounded comparison shown, against 12 same-model peers. These are company scores, not expected investment returns. The set lists named competitors first, then companies in the same data-provider industry classification closest in market value; that classification is the provider's, not our judgment of business similarity.
| Company | Price | Market value | Score |
|---|---|---|---|
| $1142.85 Oct 2, 2026 | $1.08T | 97 5-pillar Oct 4, 2026 | |
| $17.03 Oct 2, 2026 | $883M | 95 5-pillar Oct 4, 2026 | |
| $7.19 Oct 2, 2026 | $564M | 94 5-pillar Oct 4, 2026 | |
| $47.15 Oct 2, 2026 | $872M | 93 5-pillar Oct 4, 2026 | |
| $9.99 Oct 2, 2026 | $591M | 91 5-pillar Oct 4, 2026 | |
| $4.59 Oct 2, 2026 | $669M | 88 5-pillar Oct 4, 2026 | |
| $4.45 Oct 2, 2026 | $879M | 85 5-pillar Oct 4, 2026 | |
| $262.82 Oct 2, 2026 | $464B | 78 5-pillar Oct 4, 2026 | |
| $9.75 Oct 2, 2026 | $690M | 77 5-pillar Oct 4, 2026 | |
| $2.79 Oct 2, 2026 | $222M | 69 5-pillar Oct 4, 2026 | |
| $10.94 Oct 2, 2026 | $626M | 68 5-pillar Oct 4, 2026 | |
| $219.88 Oct 2, 2026 | $32.5B | 67 5-pillar Oct 4, 2026 | |
| Prothena Corporation (PRTA) — this page | $8.36 | $438M | 28 |
Only 5-pillar scores are ranked together. Other models are not directly comparable. Price and score dates are shown separately; market-value dates are unavailable.
The records behind this page
Analyst targets & estimates
What analysts have on file
- Price target, low to high
- $30.00 – $30.00
- Consensus target
- $30.00
- Median target
- $30.00
Consensus record · Captured .
Measured against a quoted price of $8.36 (as of Oct 2, 2026).
Insider activity
Form 4 records via FMP · Of the newest 100 records, those within the last 180 days, newest dated Sep 29, 2026
- Transactions
- 46
- Identified insiders
- 15
- Purchases
- 12
- Sales
- 2
- Other transactions
- 32
Purchases and sales use the reported transaction category. Other transactions include awards, exercises, gifts, withholding and unclassified activity; an acquisition or disposition alone is not a purchase or sale. These records do not establish intent.
What has been published about Prothena Corporation (PRTA)?
What Investors Ask About Prothena Corporation (PRTA)
These answers are editorial: 1 of these 9 answers is drawn from the PRTA research dossier (written May 10, 2026 by gemini-2.0-flash); the other 8 are question templates that restate figures shown above. Figures in this section are not part of the source register.
What does the MoonshotScore mean for PRTA?
PRTA carries the MoonshotScore stated above — the Weak band. This is an educational research signal, not a buy or sell recommendation. The number comes from the five-pillar engine (business quality, financial safety, valuation, growth durability, momentum), re-ranked daily against sector peers. Prothena Corporation plc is a late-stage clinical biotechnology company focused on developing novel therapies for life-threatening diseases.
Is PRTA a good stock to buy?
Stock Expert AI does not rate PRTA buy, sell or hold. Prothena Corporation plc carries a MoonshotScore, in the Weak band, a research rating against its peers rather than a forecast. Whether it fits is your call: check what it sells, whether it earns and what the price assumes. This is educational content, not investment advice.
What is the PRTA stock price today?
The last price recorded on this page for Prothena Corporation plc (PRTA) is $8.36, as of the Oct 2, 2026 trading session (source: Financial Modeling Prep (FMP) · quote). It is a provider snapshot, not a live exchange feed, so check a brokerage quote before you trade.
What is the PRTA price target?
The analyst consensus price target for Prothena Corporation plc (PRTA) is $30.00 (range $30.00 to $30.00, median $30.00), per FMP data captured Oct 5, 2026. Targets are analyst opinions and change often; they are not a Stock Expert AI forecast.
What are the main risks for PRTA?
Prothena faces significant risks inherent to the biotechnology industry. Clinical trial failures represent a major risk, as negative data can lead to substantial declines in stock price.
What are the key factors to evaluate for PRTA?
Prothena Corporation plc (PRTA) holds a MoonshotScore in the low range. Analysts target $30.00 (+259%). Expanding these partnerships or securing new collaborations represents a key growth driver. Not financial advice.
How frequently does PRTA data refresh on this page?
PRTA's price is the last quote we recorded, from the Oct 2, 2026 trading session. Pages are served from a cache, so the copy you are reading can lag that quote. The quote is a provider snapshot, not an exchange feed. Fundamentals follow quarterly filings. V2 is recalculated from the most recent completed US trading session; the score's own date shows its last successful run.
What has driven PRTA's recent stock price performance?
Prothena Corporation plc (PRTA) moves on earnings results, analyst revisions, sector rotation, and market sentiment. Notable catalyst: Late-stage clinical pipeline with potential for near-term revenue. See the News tab for the latest drivers. Past performance does not predict future results.
Should investors consider PRTA overvalued or undervalued right now?
Prothena Corporation plc (PRTA) is loss-making, so its trailing P/E is negative (-10.75x) and not usable for valuation — lean on price-to-sales and cash flow in the Financials tab. Analysts target $30.00 (+259%) — upside seen. Compare P/E, P/S, and EV/EBITDA against sector peers for a full view.
Disclaimer: This content is for informational purposes only and does not constitute investment advice. Always do your own research and consult a financial advisor.
Machine-generated analysis by Stock Expert AI — model gemini-2.0-flash, generated May 10, 2026. Editorial oversight is systemic, not page-by-page. Editorially accountable: Sedat ANAK, Founder and Editor-in-Chief.
Sources — records for every figure on this page (22 figures)
The 22 rows below are exactly the facts the evidence-backed sections of this page printed — the 10-second verdict, the MoonshotScore, price and market value, the five questions with their receipts, and the records behind this page. Known dates and sources are recorded on their own rows; an em dash or UNRECORDED tier preserves a stored observation without inventing either. The quarterly income statement is provider-standardized (FMP) under one row, and scale definitions — a 0-100 rating, the band ladder, the Piotroski 0–9 range — are fixed rather than measured. No number in those sections was generated by a model. The register does not cover quoted third-party headlines, the dated council readings, or the Frequently Asked Questions; each of those says where it came from where it stands.
"As of" is the date the value is true for where the source carries one — a quarter end, a filing date, a price close, the day the score was computed. A cached observation with no source date remains undated; the page publication date is not used as a substitute.
FMP — 14 facts from Financial Modeling Prep endpoint families
| Fact ID | Fact | Value as shown | As of | Tier | Source |
|---|---|---|---|---|---|
px.last | Latest provided price | $8.36 | FMP | Financial Modeling Prep (FMP) · quote — Dated to the US trading session the price belongs to, derived from the quote record's timestamp (weekend and pre-open reads roll back to the previous weekday; exchange holidays are not modelled). The record does not establish an exchange execution time. Retrieved 2026-10-05T10:14:41.148Z. | |
px.change | Change on the day | -2.11% | FMP | Financial Modeling Prep (FMP) · quote | |
px.mcap | Market capitalisation | $438M | FMP | Financial Modeling Prep (FMP) · quote — Date unknown Market cap record date: 2026-10-02. FMP quote timestamp: 2026-10-02T20:00:00.000Z. Captured from FMP at 2026-10-05T10:14:39.840Z. No share-count basis is inferred; this page preserves the reported amount instead of recalculating it from shares. | |
px.change_abs | Change on the day, in dollars | −$0.18 | FMP | Financial Modeling Prep (FMP) · quote | |
fin.q_revenue | Revenue, Q2 FY2026 | $1M | FMP | Financial Modeling Prep (FMP) · income statement (quarterly) | |
px.pe | Price / earnings (trailing) | -10.75 | FMP | Financial Modeling Prep (FMP) · quote | |
px.volume | Shares traded on the day | 675.8K | FMP | Financial Modeling Prep (FMP) · quote | |
fin.q_income | Net income, Q2 FY2026 | -$19M | FMP | Financial Modeling Prep (FMP) · income statement (quarterly) | |
fin.q_table | Quarterly income statement | 4 quarters through Q2 FY2026 | FMP | Financial Modeling Prep (FMP) · income statement (quarterly), as filed | |
earn.pt | Stored analyst price targets | low $30.00 · high $30.00 · consensus $30.00 · median $30.00 | FMP | Financial Modeling Prep (FMP) · price-target consensus — Captured Oct 5, 2026 · Coverage not supplied | |
earn.pt_range | Analyst price target, low to high | $30.00 – $30.00 | FMP | Financial Modeling Prep (FMP) · price-target consensus — Captured Oct 5, 2026 · Coverage not supplied | |
earn.pt_consensus | Consensus analyst price target | $30.00 | FMP | Financial Modeling Prep (FMP) · price-target consensus — Captured Oct 5, 2026 · Coverage not supplied | |
earn.pt_median | Median analyst price target | $30.00 | FMP | Financial Modeling Prep (FMP) · price-target consensus — Captured Oct 5, 2026 · Coverage not supplied | |
own.insiders | Insider transactions via FMP | 46 transactions · 12 purchases, 2 sales, 32 other transactions · 15 identified insiders · of the newest 100 records, those within the last 180 days, newest dated Sep 29, 2026 | FMP | Financial Modeling Prep (FMP), carrying Form 4 transaction records — Purchases and sales use the reported transaction category. Other transactions include awards, exercises, gifts, withholding and unclassified activity; an acquisition or disposition alone is not a purchase or sale. These records do not establish intent. |
UNRECORDED — 6 facts from stored observations whose source was not recorded
| Fact ID | Fact | Value as shown | As of | Tier | Source |
|---|---|---|---|---|---|
earn.history | Reported versus estimated, recent quarters | EPS beat 4 of 8 | UNRECORDED | Stored earnings-history observation — Captured 2026-10-04 | |
fin.scores | Distress and quality screens | Altman Z 11.39 · Piotroski F 3 | UNRECORDED | Stored financial-scores observation — Captured 2026-10-04 · Expired observation | |
px.range52 | 52-week range | $7.73 – $11.80 | UNRECORDED | Stored company-profile observation — Captured 2026-10-04 | |
id.employees | Employees | 67 | UNRECORDED | Stored company-profile observation — Captured 2026-10-04 | |
id.ceo | Chief executive | Gene G. Kinney | UNRECORDED | Stored company-profile observation — Captured 2026-10-04 | |
fin.ratios | Return and yield ratios (trailing twelve months) | ROE -15.0% · ROA -14.5% · current ratio 25.05 · earnings yield -10.1% · free-cash-flow yield -13.8% | — | UNRECORDED | Stored key metrics — Date unknown |
OURS — 2 facts from Stock Expert AI's own score and rank
| Fact ID | Fact | Value as shown | As of | Tier | Source |
|---|---|---|---|---|---|
ours.moonshot | MoonshotScore v2 | 28 of 100 · Weak · pillars 28 / 77 / 60 / 8 / 49 | OURS | Stock Expert AI MoonshotScore v2 engine | |
ours.moonshot_change | MoonshotScore movement | 28 (stored snapshot Oct 3, 2026) → 28 (current publication computed Oct 4, 2026) (0) | OURS | Stock Expert AI current score publication and immutable score snapshots |
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