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PRTA SCHEDULE 13G/A: SEC filing

An institutional holder

Filed with the SEC on · accession 0002011420-26-000004

PRTA filed a SCHEDULE 13G/A (schedule 13g/a) with the SEC on Aug 14, 2026. An institutional holder filed an amended Schedule 13G for Prothena Corp plc, indicating a change in its passive ownership position. The stock moved -2.4% by the first close after the filing.

Summary of the filing

An institutional holder filed an amended Schedule 13G for Prothena Corp plc, indicating a change in its passive ownership position. The filing text provided contains only the EDGAR directory listing and no substantive ownership details.

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Key details

IssuerProthena Corp plc

How PRTA stock reacted

Close before

$9.08

Aug 13, 2026

First close after

-2.42%

$8.86

5 trading days

-0.55%

$9.03

Since filing

-12.22%

$7.97

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Frequently asked questions

What did PRTA file with the SEC on Aug 14, 2026?

PRTA filed a SCHEDULE 13G/A (SEC filing). An institutional holder filed an amended Schedule 13G for Prothena Corp plc, indicating a change in its passive ownership position. The filing text provided contains only the EDGAR directory listing and no substantive ownership details.

How do I read a SCHEDULE 13G/A?

A report the company filed with the SEC (the US market regulator). Start with the summary, then the key amounts and names. Compare it with the company’s earlier filings.

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 SCHEDULE 13G/A (schedule 13g/a): A report the company filed with the SEC (the US market regulator).

How did PRTA stock react to this filing?

PRTA closed at $9.08 before the filing and $8.86 on Aug 14, 2026 (-2.42%). Five trading days later: $9.03 (-0.55%).

Other PRTA SEC filings

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