Prothena

PRTA · NASDAQ

$8.50+$0.02 (+0.24%)TodayMarket closed · Oct 20, 7:30 PM ET

Prev close $8.48

PRTA analyst rating

BuyConsensus of 5 analysts over the last 12 months. 80% rate it a buy.

Strong buy0
Buy4
Hold1
Underperform0
Sell0

12-month price target · 7 analysts

Average $21.83 (+156.8% upside)

Low: $8.08
Now: $8.50
High: $37.80

Upgrades and downgrades

The latest rating actions, newest first

PRTA analyst upgrades, downgrades and rating actions
Firm	Date	Action	Rating	Price target	Hit rate
Citizens	May 8, 2026	Maintains	Market Outperform	$19.00 → $20.00	41%
RBC Capital	Feb 20, 2026	Maintains	Sector Perform	$11.00 → $12.00	44%
Citizens	Dec 1, 2025	Maintains	Market Outperform	$11.00 → $19.00	52%
HC Wainwright & Co.	Nov 7, 2025	Maintains	Buy	$20.00 → $30.00	54%
RBC Capital	Nov 7, 2025	Maintains	Sector Perform	$10.00 → $11.00	44%
Piper Sandler	Oct 28, 2025	Maintains	Overweight	$15.00 → $36.00	37%

The case for and against

Updated Feb 9, 2026

Bull case

Prothena Corp has demonstrated encouraging clinical results in reducing amyloid levels for its investigational therapies, particularly at the 200mg and 400mg dose levels, which is significant for the treatment of neurodegenerative diseases. The company has projected potential earnings of up to $105 million, approximately $2 per basic share outstanding, from development milestones related to its partnerships with Novo Nordisk and Bristol-Myers Squibb by 2026. Additionally, despite some concerns regarding elevated ARIA incidence in one of its treatments, PRX012 has shown overall favorable tolerability with low incidence of injection-site reactions, reinforcing a generally positive outlook on the company’s development pipeline.

Bear case

Prothena Corp PLC faces a negative outlook due to its continued net losses, which are expected to persist until product approval or commercialization, indicating significant financial strain in the near term. The company may need to raise additional capital to support the development of its drug candidates, which poses a risk of dilution to existing shareholders and adds uncertainty regarding future shareholder value. Moreover, potential changes in regulatory stances could introduce obstacles to product approvals, further complicating the company's financial position and its ability to generate revenue.

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