NASDAQ-Listed Bio Company Insider Acquires $1.9 Million in Stock Over One Month

From May 22 through June 4, William P. Scully—a principal shareholder and insider of Prothena Corporation plc (NASDAQ: PRTA)—acquired an additional 200,000 shares of the company’s stock in open‐market transactions.

Across three separate purchases, he spent roughly $1.91 million (about KRW 2.6 billion), bringing his direct holdings to 936,000 shares, according to SEC filings.

Although Scully also holds indirect interests through a fund vehicle and in his spouse’s name, he has clarified that he recognizes only those holdings from which he derives direct economic benefit.

Recently, Prothena’s ATTR cardiomyopathy treatment candidate, coramitug (PRX004), received Fast Track designation from the U.S. Food and Drug Administration. In partnership with Novo Nordisk, the company is now advancing a Phase 3 CLEOPATRA trial.

In February, Prothena approved a share repurchase program of up to $100 million (approximately KRW 135 billion). In its first‐quarter 2026 results, management projected it would hold roughly $255 million in cash and cash equivalents (about KRW 340 billion) by year‐end 2026.

Prothena Corporation plc is a late‐stage clinical biotech focused on targeting protein misfolding. Its antibody pipeline addresses central nervous system and rare diseases, including Parkinson’s, Alzheimer’s and ATTR amyloidosis. Headquartered in Dublin, Ireland, Prothena is co‐developing multiple clinical programs through partnerships with global pharmaceutical leaders such as Roche, Bristol Myers Squibb and Novo Nordisk.