Prothena Corp Public Ltd (PRTA)10% owner bought ~$857K

~$857K

Approx. value · 100K sh @ $8.57

314K

Holds after · shares reported

Traded

Oct 2, 2026

Filed

Oct 6, 2026

The story around this disclosure

Every dated public record OQRO holds about the company from 60 days before to 120 days after, oldest first. It shows what was going on; none of it is a stated reason for the trade.

1. Aug 6, 2026Company filing · Form 8-K · ResultsReported its results
2. Sep 28, 2026Insider · 4 days before an 8-K10% owner purchased ~$890K of PRTA shares in the open market
3. Sep 29, 2026Insider · 3 days before an 8-K10% owner purchased ~$1.41M of PRTA shares in the open market
4. Oct 2, 2026 · this disclosureInsider10% owner purchased ~$857K of PRTA shares in the open market

What came next

1. Oct 2, 2026Company filing · Form 8-K · Executive changeChanged a top executive or board member“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.”
2. Oct 7, 2026Insider10% owner purchased ~$1.05M of PRTA shares in the open market
3. Oct 8, 2026Insider10% owner purchased ~$771K of PRTA shares in the open market

How to read SEC Form 4

Form 4 is the filing that officers, directors and owners of more than 10% of a US-listed company must send to the SEC within two business days after they buy, sell or otherwise change their holding of the company's stock.

Full guide: What is an SEC Form 4?

What else is on file for Prothena Corp Public Ltd

For Prothena Corp Public Ltd, OQRO holds 5 insider filings (SEC Form 4 or Form 144) dated in the last 90 days.

These are records OQRO holds, counted by their date, not a measure of how much trading took place. Routine paperwork such as option exercises and tax withholding is left out. Everything for the company is on its PRTA page.

Other recent filings by SCULLY WILLIAM P, 10% owner

• SEC Form 4 at Prothena Corp Public Ltd (PRTA)Oct 9, 2026
• SEC Form 4 at Prothena Corp Public Ltd (PRTA)Oct 9, 2026
• SEC Form 4 at Prothena Corp Public Ltd (PRTA)Oct 1, 2026
• SEC Form 4 at Prothena Corp Public Ltd (PRTA)Sep 30, 2026
• SEC Form 4 at Prothena Corp Public Ltd (PRTA)May 2, 2025

The full history of SCULLY WILLIAM P, 10% owner is on the profile page.

How this filing works

• SEC Form 4
• Open-market purchase
• Rule 10b5-1 trading plans

Other disclosures at Prothena Corp Public Ltd

• SEC Form 4Oct 9, 2026
• SEC Form 4Oct 9, 2026
• SEC Form 4Oct 1, 2026
• SEC Form 4Sep 30, 2026
• SEC Form 13F-HRMay 15, 2026
• SEC Form 13F-HRFeb 13, 2026

Everything OQRO holds on this company is on its PRTA page.