Prothena (PRTA) Chief Accounting Officer Karin L Walker Sells 15,000 Shares

What Happened
Karin L. Walker, Chief Accounting Officer of Prothena plc (PRTA), had 15,000 restricted stock units (RSUs) vest on July 28, 2026. Those RSUs converted into 15,000 ordinary shares (recorded as an exercise/conversion, code M), and 15,000 shares were surrendered to the issuer (code D) to satisfy withholding/tax obligations at $8.56 per share, resulting in $128,400 of consideration to the issuer. The conversion itself is shown at $0.00 (typical for vested RSUs that convert without purchase price).

Key Details

• Transaction date: July 28, 2026 (Form 4 filed July 30, 2026). Filing appears timely.
• Actions reported: conversion/exercise of RSUs (M) and disposition to issuer for tax withholding (D).
• Price/value: shares withheld at $8.56 each; total $128,400. Conversion entry shows $0.00 per share.
• Shares owned after transaction: not specified in this filing.
• Footnotes: F1 = each RSU converts to one share on vesting; F2/F3 = these 15,000 RSUs came from a July 28, 2025 grant of 25,000 RSUs, moved to Table II, and are fully vested as of July 28, 2026. The remaining 10,000 RSUs from that grant remain subject to vesting.
• No 10b5-1 plan or late filing flagged in this report.

Context
This was not an open-market sale but a routine surrender of vested RSU shares to the company to cover tax withholding (effectively a cashless/withholding disposition). Such withholding disposals are common and typically reflect tax obligations rather than a discretionary insider sell signal.