Arthur W. Homan, 10% Owner at PROTHENA CORP PUBLIC LTD CO (PRTA), bought 162,000 shares at $8.68 ($1.4M) on 2026-09-29, disclosed to the SEC on 2026-09-30.
10% shareholder Arthur W. Homan purchased $1.41M of PRTA at $8.68, marking the largest insider purchase in the company's history and signaling confidence despite recent stock declines. This significant capital commitment by a major shareholder may provide a floor for the stock as it trades near its 52-week low.
PRTA is down 9.99% over the past year and 6.04% over the last 30 days, currently trading at $8.785, which is 25.36% below its 52-week high of $11.77 and 12.41% above its 52-week low of $7.815.
1) Q2 2026 earnings on June 30, 2026: Prothena beat adjusted Q2 loss estimates and reaffirmed 2026 cash-use guidance. 2) Milestone decision: Recent news highlights partner pipeline progress as a key milestone decision nears. 3) Largest ever insider purchase: The signal_flags indicates this is the largest insider purchase ever recorded for PRTA.
1) High short interest: The stock has a short interest of 20.05% of the float, indicating significant bearish sentiment. 2) Revenue miss: In the Q2 2026 earnings report, Prothena missed revenue estimates by 1.94%.
Nothing distinguishes this filing.
| Filing → |
| PRTA | BUY | 2026-10-09 | $1.8M | — | Filing → |
| PRTA | BUY | 2026-10-06 | $857K | — | Filing → |
| PRTA | BUY | 2026-09-29 | $890K | — | Filing → |