• Live Feeds
    • Press Releases
    • Insider Trading
    • FDA Approvals
    • Analyst Ratings
    • Insider Trading
    • SEC filings
    • Market insights
  • Analyst Ratings
  • Alerts
  • Subscriptions
  • Settings
  • RSS Feeds
Quantisnow Logo
  • Live Feeds
    • Press Releases
    • Insider Trading
    • FDA Approvals
    • Analyst Ratings
    • Insider Trading
    • SEC filings
    • Market insights
  • Analyst Ratings
  • Alerts
  • Subscriptions
  • Settings
  • RSS Feeds
PublishGo to App
    Quantisnow Logo

    © 2026 quantisnow.com
    Democratizing insights since 2022

    Services
    Live news feedsRSS FeedsAlertsPublish with Us
    Company
    AboutQuantisnow PlusContactJobsAI superconnector for talent & startupsNEWLLM Arena
    Legal
    Terms of usePrivacy policyCookie policy

    SEC Form SC 13G filed by Prothena Corporation plc

    1/24/24 8:25:19 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care
    Get the next $PRTA alert in real time by email
    SC 13G 1 Prothena_Corp_PLC.txt UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G UNDER THE SECURITIES EXCHANGE ACT OF 1934 INITIAL FILING PROTHENA CORP PLC (NAME OF ISSUER) COMMON STOCK (TITLE OF CLASS OF SECURITIES) G72800108 (CUSIP NUMBER) 12/31/2023 (DATE OF EVENT WHICH REQUIRES FILING OF THIS STATEMENT) CHECK THE APPROPRIATE BOX TO DESIGNATE THE RULE PURSUANT TO WHICH THIS SCHEDULE IS FILED: (X) RULE 13D-1 (B) ( ) RULE 13D-1 (C) ( ) RULE 13D-1 (D) *THE REMAINDER OF THIS COVER PAGE SHALL BE FILLED OUT FOR A REPORTING PERSON`S INITIAL FILING ON THIS FORM WITH RESPECT TO THE SUBJECT CLASS OF SECURITIES, AND FOR ANY SUBSEQUENT AMENDMENT CONTAINING INFORMATION WHICH WOULD ALTER THE DISCLOSURES PROVIDED IN A PRIOR COVER PAGE. THE INFORMATION REQUIRED IN THE REMAINDER OF THIS COVER PAGE SHALL NOT BE DEEMED TO BE "FILED" FOR THE PURPOSE OF SECTION 18 OF THE SECURITIES EXCHANGE ACT OF 1934 ("ACT") OR OTHERWISE SUBJECT TO THE LIABILITIES OF THAT SECTION OF THE ACT BUT SHALL BE SUBJECT TO ALL OTHER PROVISIONS OF THE ACT (HOWEVER, SEE THE NOTES). CUSIP NO:G72800108 13G Page 2 of 5 Pages 1. NAME OF REPORTING PERSON: STATE STREET CORPORATION I.R.S. IDENTIFICATION NO. OF THE ABOVE PERSON: 04-2456637 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP NOT APPLICABLE 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION BOSTON, MASSACHUSETTS 5. SOLE VOTING POWER 0 SHARES 6. SHARED VOTING POWER 2,641,813 7. SOLE DISPOSITIVE POWER 0 SHARES 8. SHARED DISPOSITIVE POWER 2,758,564 9. AGGREGATED AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,758,564 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES NOT APPLICABLE 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.14% 12. TYPE OF REPORTING PERSON HC CUSIP NO: G72800108 13G Page 3 of 5 Pages ITEM 1. (A) NAME OF ISSUER PROTHENA CORP PLC (B) ADDRESS OF ISSUER`S PRINCIPAL EXECUTIVE OFFICES 77 SIR JOHN ROGERSON`S 1/64 13/32S QUAY BLOCK C, GRAND CANAL DOCKLANDS DUBLIN 2 D02 VK60 IRELAND ITEM 2. (A) NAME OF PERSON FILING STATE STREET CORPORATION (B) ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE STATE STREET FINANCIAL CENTER 1 CONGRESS STREET, SUITE 1 BOSTON, MA 02114-2016 (FOR ALL REPORTING PERSONS) (C) CITIZENSHIP: SEE ITEM 4 (CITIZENSHIP OR PLACE OF ORGANIZATION) OF COVER PAGES (D) TITLE OF CLASS OF SECURITIES COMMON STOCK (E) CUSIP NUMBER: G72800108 ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO RULE 13D-1(B), OR 13D-2(B) OR (C), CHECK WHETHER THE PERSON FILING IS A: SEE ITEM 12(TYPE OF REPORTING PERSON) OF THE COVER PAGE FOR EACH REPORTING PERSON AND THE TABLE BELOW, WHICH EXPLAINS THE MEANING OF THE TWO LETTER SYMBOLS APPEARING IN ITEM 12 OF THE COVER PAGES. SYMBOL CATEGORY BK BANK AS DEFINED IN SECTION 3(A) (6) OF THE ACT. IC INSURANCE COMPANY AS DEFINED IN SECTION 3 (A) (19) OF THE ACT IC INVESTMENT COMPANY REGISTERED UNDER SECTION 8 OF THE INVESTMENT COMPANY ACT OF 1940. IA AN INVESTMENT ADVISOR IN ACCORDANCE WITH RULE 13D-1(B) (1) (II) (E). EP AN EMPLOYEE BENEFIT PLAN OR ENDOWMENT FUND IN ACCORDANCE WITH RULE 13D-1(B) (1) (II) (F) . HC A PARENT HOLDING COMPANY OR CONTROL PERSON IN ACCORDANCE WITH RULE 13D-1(B)(1)(II) (G). SA A SAVINGS ASSOCIATIONS AS DEFINED IN SECTION 3(B) OF THE FEDERAL DEPOSIT INSURANCE ACT (12 U.S.C. 1813). CP A CHURCH PLAN THAT IS EXCLUDED FROM THE DEFINITION OF AN INVESTMENT COMPANY UNDER SECTION 3(C)(14) OF THE INVESTMENT COMPANY ACT OF 1940. CUSIP NO:G72800108 13G Page 4 of 5 Pages ITEM 4. OWNERSHIP THE INFORMATION SET FORTH IN ROWS 5 THROUGH 11 OF THE COVER PAGE HERETO FOR EACH OF THE REPORTING PERSONS IS INCORPORATED HEREIN BY REFERENCE. ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF CLASS NOT APPLICABLE ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON NOT APPLICABLE ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY OR CONTROL PERSON SEE EXHIBIT 1 ATTACHED HERETO ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP NOT APPLICABLE ITEM 9. NOTICE OF DISSOLUTION OF GROUP NOT APPLICABLE CUSIP NO:G72800108 13G Page 5 of 5 Pages ITEM 10. CERTIFICATION BY SIGNING BELOW I CERTIFY THAT, TO THE BEST OF MY KNOWLEDGE AND BELIEF, THE SECURITIES REFERRED TO ABOVE WERE ACQUIRED AND ARE HELD IN THE ORDINARY COURSE OF BUSINESS AND WERE NOT ACQUIRED AND ARE NOT HELD FOR THE PURPOSE OR WITH THE EFFECT OF CHANGING OR INFLUENCING THE CONTROL OF THE ISSUER OF THE SECURITIES AND WERE NOT ACQUIRED AND ARE NOT HELD IN CONNECTION WITH OR AS A PARTICIPANT IN ANY TRANSACTION HAVING THAT PURPOSE OR EFFECT. SIGNATURES AFTER REASONABLE INQUIRY AND TO THE BEST OF HIS KNOWLEDGE AND BELIEF, EACH OF THE UNDERSIGNED CERTIFIES THAT THE INFORMATION SET FORTH IN THIS STATEMENT IS TRUE, COMPLETE AND CORRECT. STATE STREET CORPORATION ELIZABETH SCHAEFER SENIOR VICE PRESIDENT, DEPUTY CONTROLLER EXHIBIT 1 THE FOLLOWING TABLE LISTS THE IDENTITY AND ITEM 3 CLASSIFICATION OF EACH SUBSIDIARY OF STATE STREET CORPORATION, THE PARENT HOLDING COMPANY, THAT BENEFICIALLY OWNS THE ISSUER`S SECURITIES. PLEASE REFER TO ITEM 3 OF THE ATTACHED SCHEDULE 13G FOR A DESCRIPTION OF EACH OF THE TWO-LETTER SYMBOLS REPRESENTING THE ITEM 3 CLASSIFICATION BELOW. SUBSIDIARY ITEM 3 CLASSIFICATION SSGA FUNDS MANAGEMENT, INC. IA STATE STREET GLOBAL ADVISORS EUROPE LIMITED IA STATE STREET GLOBAL ADVISORS LIMITED IA STATE STREET GLOBAL ADVISORS TRUST COMPANY IA STATE STREET GLOBAL ADVISORS, AUSTRALIA, LIMITED IA NOTE: ALL OF THE LEGAL ENTITIES ABOVE ARE DIRECT OR INDIRECT SUBSIDIARIES OF STATE STREET CORPORATION.
    Get the next $PRTA alert in real time by email

    Crush Q1 2026 with the Best AI Superconnector

    Stay ahead of the competition with Standout.work - your AI-powered talent-to-startup matching platform.

    AI-Powered Inbox
    Context-aware email replies
    Strategic Decision Support
    Get Started with Standout.work

    Recent Analyst Ratings for
    $PRTA

    DatePrice TargetRatingAnalyst
    5/28/2025$4.00Neutral → Underperform
    BofA Securities
    5/27/2025Outperform → Perform
    Oppenheimer
    5/27/2025$6.00Buy → Hold
    Jefferies
    5/27/2025Overweight → Neutral
    Cantor Fitzgerald
    12/20/2024$40.00Buy
    Chardan Capital Markets
    1/30/2024$68.00 → $38.00Buy → Neutral
    BofA Securities
    12/12/2023$62.00Buy
    Deutsche Bank
    4/24/2023$80.00Outperform
    SVB Securities
    More analyst ratings

    $PRTA
    Press Releases

    Fastest customizable press release news feed in the world

    View All

    Prothena to Report Fourth Quarter and Full Year 2025 Financial Results on February 19, 2026

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that it will report its fourth quarter and full year 2025 financial results on Thursday, February 19, 2026, after the close of the U.S. financial markets. The announcement will be followed by a live audio conference call at 4:30 PM ET. The conference call will be made available on the Company's website at www.prothena.com under the Investors tab in the Events and Presentations section. Following the live audio webcast, a replay will be available on the Company's website for at least 90 days. T

    2/12/26 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena Announces Board of Directors Update

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that Paula Cobb will step down from Prothena's Board of Directors to join Manifold Bio as its Chief Operating Officer. During her six-year tenure, Ms. Cobb played a significant role in which she made key contributions to the Company's vision and strategy. "I would like to thank Paula for her many contributions during the past six years. As a biotechnology executive with wide-ranging global development, business strategy and commercial expertise, she provided valuable insights to the board and lea

    12/12/25 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena Announces Poster Presentation on its TDP-43 CYTOPE® Program at Neuroscience 2025

    TDP-43 CYTOPE® preclinical data demonstrates the potential of Prothena's CYTOPE technology as a novel modality for delivering large molecules into cells, enabling precise targeting of intracellular disease pathways Systemically-administered TDP-43 CYTOPE rapidly and efficiently distributed to the brain and periphery, internalized into the cytosol and significantly reduced intracellular TDP-43 pathology in an ALS mouse model TDP-43 CYTOPE meaningfully reduced intracellular TDP-43 pathology and associated RNA dysregulation caused by cryptic exon inclusions - key pathogenic features of TDP-43 proteinopathies - in a human-derived neuronal cell line   Prothena Corporation plc (NASDAQ

    11/19/25 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Insider Trading

    Insider transactions reveal critical sentiment about the company from key stakeholders. See them live in this feed.

    View All

    Chief Scientific Officer Zago Wagner M. was granted 85,000 units of Ordinary Shares (SEC Form 4)

    4 - PROTHENA CORP PUBLIC LTD CO (0001559053) (Issuer)

    7/30/25 5:52:29 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Chief Accounting Officer Walker Karin L was granted 25,000 units of Ordinary Shares (SEC Form 4)

    4 - PROTHENA CORP PUBLIC LTD CO (0001559053) (Issuer)

    7/30/25 5:52:14 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Chief Development Officer Swanson Chad J. was granted 85,000 units of Ordinary Shares (SEC Form 4)

    4 - PROTHENA CORP PUBLIC LTD CO (0001559053) (Issuer)

    7/30/25 5:52:01 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Analyst Ratings

    Analyst ratings in real time. Analyst ratings have a very high impact on the underlying stock. See them live in this feed.

    View All

    Prothena downgraded by BofA Securities with a new price target

    BofA Securities downgraded Prothena from Neutral to Underperform and set a new price target of $4.00

    5/28/25 8:10:50 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena downgraded by Oppenheimer

    Oppenheimer downgraded Prothena from Outperform to Perform

    5/27/25 9:09:16 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena downgraded by Jefferies with a new price target

    Jefferies downgraded Prothena from Buy to Hold and set a new price target of $6.00

    5/27/25 9:09:16 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    SEC Filings

    View All

    Prothena Corporation plc filed SEC Form 8-K: Leadership Update, Financial Statements and Exhibits

    8-K - PROTHENA CORP PUBLIC LTD CO (0001559053) (Filer)

    12/12/25 4:26:08 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena Corporation plc filed SEC Form 8-K: Submission of Matters to a Vote of Security Holders, Financial Statements and Exhibits

    8-K - PROTHENA CORP PUBLIC LTD CO (0001559053) (Filer)

    11/19/25 4:30:57 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Amendment: SEC Form SCHEDULE 13G/A filed by Prothena Corporation plc

    SCHEDULE 13G/A - PROTHENA CORP PUBLIC LTD CO (0001559053) (Subject)

    11/12/25 3:47:28 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Insider Purchases

    Insider purchases reveal critical bullish sentiment about the company from key stakeholders. See them live in this feed.

    View All

    Large owner Scully William P received a gift of 430,000 units of Ordinary Shares, bought $2,749,916 worth of Ordinary Shares (207,436 units at $13.26) and gifted 747,700 units of Ordinary Shares, decreasing direct ownership by 7% to 735,993 units (SEC Form 4)

    4 - PROTHENA CORP PUBLIC LTD CO (0001559053) (Issuer)

    5/2/25 10:29:05 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Leadership Updates

    Live Leadership Updates

    View All

    Prothena Announces Board of Directors Update

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that Paula Cobb will step down from Prothena's Board of Directors to join Manifold Bio as its Chief Operating Officer. During her six-year tenure, Ms. Cobb played a significant role in which she made key contributions to the Company's vision and strategy. "I would like to thank Paula for her many contributions during the past six years. As a biotechnology executive with wide-ranging global development, business strategy and commercial expertise, she provided valuable insights to the board and lea

    12/12/25 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena Reports Third Quarter 2024 Financial Results and Business Highlights

    Net cash used in operating and investing activities was $45.2 million and $102.5 million for the third quarter and first nine months of 2024, respectively; quarter-end cash and restricted cash position was $520.1 million PRX012, a potential single-injection once-monthly subcutaneous treatment, is designed to address the unmet need of millions of patients with presymptomatic or early symptomatic Alzheimer's disease; Prothena expects to report multiple clinical readouts starting in mid-2025 and continuing throughout the year from the ongoing Phase 1 ASCENT clinical trials Results from partner Roche evaluating prasinezumab in patients with early Parkinson's disease from the Phase 2 PASA

    11/12/24 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena Reports First Quarter 2024 Financial Results and Business Highlights

    Net cash used in operating and investing activities was $73.2 million in the first quarter of 2024; quarter-end cash and restricted cash position was $548.7 million Advanced potential best-in-class Alzheimer's disease portfolio: initial data supportive of ongoing Phase 1 clinical trial for PRX012, an anti-amyloid beta antibody; received FDA clearance for IND application and Fast Track designation for PRX123, a dual amyloid beta/tau vaccine; Phase 2 clinical trial initiated in patients with early Alzheimer's disease for BMS-986446 (formerly PRX005) by partner Bristol Myers Squibb Strengthened leadership position in the amyloidosis community with ongoing enrollment of the confirmatory

    5/8/24 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Financials

    Live finance-specific insights

    View All

    Prothena to Report Fourth Quarter and Full Year 2025 Financial Results on February 19, 2026

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that it will report its fourth quarter and full year 2025 financial results on Thursday, February 19, 2026, after the close of the U.S. financial markets. The announcement will be followed by a live audio conference call at 4:30 PM ET. The conference call will be made available on the Company's website at www.prothena.com under the Investors tab in the Events and Presentations section. Following the live audio webcast, a replay will be available on the Company's website for at least 90 days. T

    2/12/26 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena to Report Third Quarter 2025 Financial Results on November 6

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that it will report its third quarter and first nine months of 2025 financial results on Thursday November 6, 2025, after the close of the U.S. financial markets. Consistent with past practice, the Company will not be conducting a conference call in conjunction with the financial results release on November 6. About Prothena Prothena Corporation plc is a late-stage clinical biotechnology company with expertise in protein dysregulation and a pipeline of investigational therapeutics with the p

    10/30/25 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Prothena to Report Second Quarter 2025 Financial Results on August 4

    Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that it will report its second quarter and first six months of 2025 financial results on Monday, August 4, 2025, after the close of the U.S. financial markets. Consistent with past practice, the Company will not be conducting a conference call in conjunction with the financial results release on August 4. About Prothena Prothena Corporation plc is a late-stage clinical biotechnology company with expertise in protein dysregulation and a pipeline of investigational therapeutics with the potent

    7/28/25 4:05:00 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    $PRTA
    Large Ownership Changes

    This live feed shows all institutional transactions in real time.

    View All

    Amendment: SEC Form SC 13G/A filed by Prothena Corporation plc

    SC 13G/A - PROTHENA CORP PUBLIC LTD CO (0001559053) (Subject)

    11/14/24 1:22:34 PM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Amendment: SEC Form SC 13G/A filed by Prothena Corporation plc

    SC 13G/A - PROTHENA CORP PUBLIC LTD CO (0001559053) (Subject)

    11/13/24 7:00:50 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care

    Amendment: SEC Form SC 13G/A filed by Prothena Corporation plc

    SC 13G/A - PROTHENA CORP PUBLIC LTD CO (0001559053) (Subject)

    11/13/24 6:06:27 AM ET
    $PRTA
    Biotechnology: Pharmaceutical Preparations
    Health Care