# Prothena Corporation plc (PRTA)

> Source: Nexqual · https://nexqual.com/PRTA · data as of 2026-10-28 20:00 UTC · cite as "Nexqual, Prothena Corporation plc (PRTA), nexqual.com/PRTA" · informational, not investment advice.

**Price:** USD 9.1 (+3.29% on the day) · last close of Oct 28, 2026; US market after hours, not a live price. Prev close 8.81 · day 8.61–9.22 · 52w 7.73–11.8 · market cap $467M · NMS

## Key facts
- Last four reported quarters (through Jun 30, 2026): revenue $54.5M, net income -$44.0M (-80.7% margin) (SEC filings).
- Analysts: Buy (mean 2.43 on a 1–5 scale) (7 analysts), mean target USD 21.4 (range 8–36).
- Total return with dividends: 1Y -14.6% vs S&P 500 +13.6%; 5Y -83.6% vs S&P 500 +79.8%.
- Next earnings: 2026-11-05, EPS estimate USD -0.3, revenue estimate $8.2M.

## Financials (SEC 10-K; TTM = last four 10-Q/10-K quarters)
| USD | FY2021 | FY2022 | FY2023 | FY2024 | FY2025 | TTM |
|---|---|---|---|---|---|---|
| Revenue | $201M | $53.9M | $91.4M | $135M | $9.7M | $54.5M |
| Operating income | $72.0M | -$132M | -$191M | -$155M | -$215M | -$55.5M |
| Net income | $67.0M | -$117M | -$147M | -$122M | -$244M | -$44.0M |
| EPS (diluted) | $1.38 | -$2.47 | -$2.76 | -$2.27 | -$4.53 | — |
| Operating margin | 35.9% | -244.1% | -209.1% | -114.4% | -2216.4% | -101.8% |
| Net margin | 33.4% | -217.0% | -160.9% | -90.5% | -2520.6% | -80.7% |
| Revenue growth | +23414.3% | -73.1% | +69.5% | +47.9% | -92.8% | — |
| Cash + short-term investments | $579M | $710M | $619M | $471M | $308M | — |
Fiscal years end Dec. EPS is split-adjusted.

## Valuation (price ÷ last four quarters, through Jun 30, 2026)
P/S 8.6x · P/B 1.6x · Earnings yield -9.42%

## Analysts
Consensus Buy (mean 2.43 on a 1–5 scale), 7 analysts; mean target USD 21.4 (low 8, high 36).

## Total return (dividends reinvested)
|  | 1Y (from 2025-10-29) | 5Y (from 2021-10-25) |
|---|---|---|
| Total return | -14.6% | -83.6% |
| S&P 500 (SPY) | +13.6% | +79.8% |
| Per year | -14.6% | -30.3% |
| Volatility (annualized) | 47.6% | 65.9% |
| Max drawdown | -31.3% (Apr 2026→Jun 2026) | -94.2% (May 2023→May 2025) |

## Peers (Biotechnology)
RYTM (Rhythm Pharmaceuticals, Inc.) USD 91.97 -0.23% · ORKA (Oruka Therapeutics, Inc.) USD 95.97 +0.17% · IOVA (Iovance Biotherapeutics, Inc.) USD 14.81 +1.58% · IONS (Ionis Pharmaceuticals, Inc.) USD 44.9 +2.14% · AXSM (Axsome Therapeutics, Inc.) USD 143.51 +0.92% · PRAX (Praxis Precision Medicines, Inc) USD 285.48 +6.69%

## More
Full page: https://nexqual.com/PRTA · Free keyless MCP server with the same data and citations: https://mcp.nexqual.com/mcp · Guide for agents: https://nexqual.com/agents · https://nexqual.com/llms.txt

## Supply chain and relationships (SEC annual reports)

Named in PRTA's own 10-K filed 2026-02-27 (https://www.sec.gov/Archives/edgar/data/1559053/000155905326000008/prta-20251231.htm):

| Relationship | Company | Sentence in the filing |
|---|---|---|
| Partner | Novo Nordisk (NVO) | "Hoffman-La Roche Ltd and Hoffmann-La Roche Inc. (together "Roche"), Bristol Myers Squibb Company ("BMS"), and Novo Nordisk, and amounts we may receive under such collaborations; the sufficiency of our cash position to fu…" |
| Partner | Roche Ltd and Hoffmann-La Roche | "Hoffman-La Roche Ltd and Hoffmann-La Roche Inc. (together "Roche"), Bristol Myers Squibb Company ("BMS"), and Novo Nordisk, and amounts we may receive under such collaborations; the sufficiency of our cash position to fu…" |
| Partner | Celgene Switzerland | "Our cash and cash equivalents may also be potentially supplemented in the future by proceeds from our collaboration partners BMS (formerly Celgene), Roche and milestone payments from Novo Nordisk." |
| Partner | Prothena Biosciences | "BMS exercised its US Rights for the tau/BMS-986446 (formerly PRX005) Collaboration Target and on July 30, 2021, PBL entered into a U.S. License Agreement granting BMS an exclusive license to develop, manufacture and comm…" |

## Revenue by product line (quarter ended 2026-06-30)

| Line | Revenue | Share | YoY |
|---|---|---|---|
| Collaboration revenue | $1.0M | 100.0% | -77.1% |
| Total revenue | $1.0M | 100% | — |

## Company outlook (8-K filed 2026-08-06)

- "Roche is currently evaluating prasinezumab in the Phase 3 PARAISO trial, with primary completion expected in 2029," said Gene Kinney, Ph.D., President and Chief Executive Officer, Prothena. "In addition, Novo Nordisk is conducting the Phase 3 CLEOPATTRA clinical trial evaluating coramitug in patients with ATTR amyloidosis with cardiomyopathy, with primary completion expected in 2029."
- "We also expect our partner Bristol Myers Squibb to complete the ongoing Phase 2 TargetTau-1 clinical trial evaluating moponetug (BMS-986446) in patients with early Alzheimer's disease in the first half of 2027."

## Analyst estimates and revisions

| Period | EPS est. | 90d ago | Change | Revenue est. | Analysts |
|---|---|---|---|---|---|
| Current quarter (ends 2026-09-30) | $-0.30 | $-0.38 | +$0.08 | $8.2M | 2 |
| Next quarter (ends 2026-12-31) | $0.52 | $0.21 | +141.9% | $22.4M | 2 |
| Current fiscal year (ends 2026-12-31) | $0.64 | $0.05 | +1180.0% | $82.7M | 1 |
| Next fiscal year (ends 2027-12-31) | $-1.31 | $-1.31 | $0.00 | $21.0M | 2 |

## Options: expected move (Cboe, 15-min delayed)

Expected move by 2026-12-18 (includes earnings 2026-11-05): ±20.1%; last 8 reports averaged ±3.1%.

| Expiration | Days | ATM IV | Expected move |
|---|---|---|---|
| 2026-12-18 | 51 | 66.4% | ±20.1% |
| 2027-01-15 | 79 | 57.5% | ±21.6% |
| 2027-03-19 | 142 | 70.6% | ±38.3% |

## Earnings history and stock reaction
| Results filed | Quarter | EPS | Consensus | Surprise | Stock reaction |
|---|---|---|---|---|---|
| Aug 6, 2026 | Quarter ended Jun 30, 2026 | −$0.31 | −$0.38 | Beat +18.4% | +3.2% |
| May 7, 2026 | Quarter ended Mar 31, 2026 | $0.68 | −$0.30 | Beat +$0.98 | -4.0% |
| Feb 19, 2026 | Quarter ended Dec 31, 2025 | −$0.46 | −$0.46 | In line | -0.8% |
| Nov 6, 2025 | Quarter ended Sep 30, 2025 | −$0.67 | −$0.54 | Miss −24.1% | +2.8% |
| Aug 4, 2025 | — | — | — | — | +3.2% |
| May 8, 2025 | — | — | — | — | +1.9% |
| Feb 20, 2025 | — | — | — | — | +3.9% |
| Nov 12, 2024 | — | — | — | — | -4.7% |
EPS as reported against the analyst consensus before the release; surprise uses the cent-rounded figures shown (in dollars when EPS and consensus have opposite signs). Stock reaction = close before the results to close after (the first close following a release after the bell or before the open).

## Recent SEC filings (last 120 days)
| Filed | Form | What it says | Filing |
|---|---|---|---|
| 2026-10-02 | 8-K | Director or executive officer change, or pay arrangement — “On October 2, 2026, Chad J. Swanson, Ph.D., Chief Development Officer of Prothena Corporation plc (the "Company") notified the Company that he is resigning from the Company effective October 9, 2026. Dr. Swanson is resigning to accept a position with one of the Company's strategic partners, and, as part of his new role, will assume a leadership role over a program partnered with the Company.” | https://www.sec.gov/Archives/edgar/data/1559053/000155905326000024/0001559053-26-000024-index.htm |
| 2026-08-19 | Schedule 13G/A | Fennell Todd W.: 10.2% of shares, passive 5%+ holder (amended) | https://www.sec.gov/Archives/edgar/data/1559053/000201142026000007/0002011420-26-000007-index.htm |
| 2026-08-14 | Schedule 13G/A | Fennell Todd W.: 9.8% of shares, passive 5%+ holder (amended) | https://www.sec.gov/Archives/edgar/data/1559053/000201142026000004/0002011420-26-000004-index.htm |
| 2026-08-06 | 10-Q | Quarterly report · period ended Jun 30, 2026 | https://www.sec.gov/Archives/edgar/data/1559053/000155905326000022/0001559053-26-000022-index.htm |
| 2026-08-06 | 8-K | Quarterly results | https://www.sec.gov/Archives/edgar/data/1559053/000155905326000021/0001559053-26-000021-index.htm |
| 2026-08-06 | Schedule 13G/A | FMR LLC, Abigail P. Johnson: 13.8% of shares, passive 5%+ holder (amended) | https://www.sec.gov/Archives/edgar/data/1559053/000031506626002104/0000315066-26-002104-index.htm |
| 2026-07-29 | Schedule 13G/A | BlackRock, Inc.: 6.9% of shares, passive 5%+ holder (amended) | https://www.sec.gov/Archives/edgar/data/1559053/000201238326002784/0002012383-26-002784-index.htm |
Source: SEC EDGAR. Quotes are the opening words of each item as filed.