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Insider BuyPRTA· · June 5, 2026, 5:47 PM UTC

A 10% owner keeps buying Prothena

William Scully adds another 50,000 shares of PRTA.

William Scully, a 10% owner of Prothena, disclosed repeated open-market purchases of PRTA totaling nearly $1M across the window. A large holder accumulating a clinical-stage biotech is the kind of pattern the cluster and magnitude factors reward.

Reporting insider: SCULLY WILLIAM P · 10% owner · discretionary, open-market

The filing, structured

SecurityDateTypeSharesPriceOwned afterHolding
Ordinary Shares, par value $0.01 per share2026-06-04Open-market purchase+50K$9.31936KDirect
DEHY Score 53 / 100Net bought $465KView the original Form 4 on SEC EDGAR →

FAQ

What insider transaction did PROTHENA CORP PUBLIC LTD CO (PRTA) report?
William Scully, a 10% owner of Prothena, disclosed repeated open-market purchases of PRTA totaling nearly $1M across the window. A large holder accumulating a clinical-stage biotech is the kind of pattern the cluster and magnitude factors reward.
Who made the purchase at $PRTA?
SCULLY WILLIAM P, 10% owner, is the reporting insider on this Form 4, a purchase of about $465K.
Was the $PRTA trade an open-market transaction or a 10b5-1 plan?
The trade was a discretionary, open-market transaction — not executed under a pre-arranged 10b5-1 plan.
What is the DEHY Score for this $PRTA filing?
This filing scored 53 out of 100 on the DEHY Score, a 0–100 triage signal for how much analyst attention a filing warrants — not a price prediction.

Structured from public SEC data within seconds of filing. The DEHY Score is a 0–100 triage signal, not investment advice or a price prediction. See methodology.