PRTA 8-K: SEC filing
Prothena
Filed with the SEC on · accession 0001559053-26-000030
PRTA filed a 8-K (current report) with the SEC on Nov 5, 2026. A report of a major event, filed within four business days: results, deals, leadership changes, bankruptcy and more. The stock moved -6.0% by the first close after the filing.
Summary of the filing
Prothena reported Q3 2026 financial results with a net loss of $16.5 million, an improvement from a $36.5 million loss in Q3 2025, and highlighted progress across its partnered clinical programs including prasinezumab, coramitug, and moponetug.
Key details
How PRTA stock reacted
Close before
$8.39
Nov 4, 2026
First close after
-5.96%
$7.89
5 trading days
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Since filing
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Click hereFrequently asked questions
What did PRTA file with the SEC on Nov 5, 2026?
PRTA filed a 8-K (SEC filing). Prothena reported Q3 2026 financial results with a net loss of $16.5 million, an improvement from a $36.5 million loss in Q3 2025, and highlighted progress across its partnered clinical programs including prasinezumab, coramitug, and moponetug.
How do I read a 8-K?
A report of a major event, filed within four business days: results, deals, leadership changes, bankruptcy and more. The "Item" number tells you the topic (e.g. 2.02 results, 5.02 executive change, 1.01 new agreement, 1.03 bankruptcy). Exhibits (99.1 press release) usually hold the details.
Why are SEC filings important?
Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A 8-K (current report): A report of a major event, filed within four business days: results, deals, leadership changes, bankruptcy and more.
How did PRTA stock react to this filing?
PRTA closed at $8.39 before the filing and $7.89 on Nov 5, 2026 (-5.96%).
Other PRTA SEC filings
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