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SCHEDULE Filed 2025-01-03 Event 2024-12-31 SEC 0000935836-25-000018 →

EcoR1 Capital, LLC PROTHENA CORP PUBLIC LTD CO PRTA

Stake: 21.50% Shares: 11,584,280 CUSIP: G72800108 Class: Ordinary Shares

Item 4 — Purpose of Transaction

The reporting persons filed this Schedule 13D because the Issuer's board of directors appointed Oleg Nodelman to serve as a director of the Issuer. On December 31, 2024, Mr. Nodelman resigned from the Issuer's board of directors. The reporting persons acquired Ordinary Shares for investment purposes based on their belief that the Issuer's Ordinary Shares, when purchased, was undervalued and represented an attractive investment opportunity. The reporting persons will routinely monitor the Issuer regarding a wide variety of factors that affect their investment considerations, including, current and anticipated future trading prices of the Ordinary Shares and other securities, the Issuer's operations, assets, prospects, financial position, and business development, Issuer's management, Issuer-related competitive and strategic matters, general economic, financial market and industry conditions, and other investment considerations. Depending on their evaluation of various factors, the reporting persons may take such actions regarding their holdings of the Issuer's securities as they deem appropriate in light of circumstances existing from time to time. Such actions may include purchasing additional Ordinary Shares in the open market, through privately negotiated transactions with third parties or otherwise, and selling at any time, in the open market, through privately negotiated transactions with third parties or otherwise, all or part of the Ordinary Shares that they now own or hereafter acquire. The reporting persons also may from time to time enter into or unwind hedging or other derivative transactions with respect to the Ordinary Shares or pledge their interests in the Ordinary Shares to obtain liquidity. In addition, from time to time the reporting persons and their representatives and advisers may communicate with other stockholders, industry participants and other interested parties about the Issuer. The reporting persons have no present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D. However, the reporting persons may recommend action to the Issuer's management, board of directors and stockholders. Any such actions could involve one or more of the events referred to in clauses (a) through (j) of Item 4 of Schedule 13D, including, potentially, one or more mergers, consolidations, sales or acquisitions of assets, changes in control, issuances, purchases, dispositions or pledges of securities or other changes in capitalization.

Cross-References

Insider Activity (last 365d)
1 transaction
1 buys · 0 sales · 0 awards/exercises
Issuer Cluster
1 13D/G filings on this issuer
0 other filings besides this one
Filer Track Record
7 filings by this filer
6 other filings in the data moat
Short Interest · settle 2026-03-31
DTC 12.32
7,016,080 shares short · -0.4% vs prior

Institutional Consensus · 2025-12-31

Held by elite portfolio managers
1 holder · $8.78M
Point72 Asset Mgmt

Form 4 Insider Transactions · last 365d

DateInsiderRoleTypeSharesPriceValue
2026-04-10 Kingston Anne Evans officer Award 100,000 $10.50 $1.05M

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