Schedule 13G: T. Rowe Price Holds 71,047 Prothena Shares, Sole Voting Power

Rhea-AI Filing Summary

T. Rowe Price Associates, Inc. reports beneficial ownership of 71,047 shares of Prothena Corporation plc common stock, equal to about 0.1% of the outstanding class. The Schedule 13G filing shows T. Rowe Price has sole voting power and sole dispositive power over the shares and identifies the filer as an investment adviser. The filing states the position is held in the ordinary course of business and not for the purpose of changing or influencing control. Items addressing group membership, ownership on behalf of others, and related classifications are marked Not Applicable.

Insights

Securities Analyst

TL;DR: Routine Schedule 13G filing disclosing a small, passive stake (71,047 shares, 0.1%) with sole voting/dispositive power.

The disclosed position is de minimis relative to total equity and is filed under Schedule 13G as an investment adviser. The report specifies sole voting and dispositive authority for 71,047 shares and confirms the holding is in the ordinary course of business and not intended to influence control. No shared power, group affiliation, or ownership on behalf of others is indicated, so the filing is informational and unlikely to affect corporate governance or market dynamics.

Portfolio Manager

TL;DR: Small, non-controlling passive position consistent with diversified institutional holdings; procedural disclosure confirms compliance.

The statement clarifies that T. Rowe Price fully controls voting and disposition for the 71,047-share stake in Prothena and that the position is held in the ordinary course of business. Because it represents approximately 0.1% of the class and the filer denies any intent to influence control, this is a routine regulatory disclosure reflecting portfolio activity rather than a strategic stake. Items related to groups and parent/subsidiary reporting are marked Not Applicable.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 6)

PROTHENA CORP PLC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

G72800108

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. G72800108

1

Names of Reporting Persons

T. Rowe Price Associates, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MARYLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 71,047.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 71,047.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

71,047.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.1 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: PROTHENA CORP PLC
(b)	Address of issuer's principal executive offices: 77 SIR JOHN ROGERSON'S QUAY, BLOCK C, GRAND CANAL DOCKLANDS, DUBLIN, L2, D02 VK60
Item 2.
(a)	Name of person filing: T. Rowe Price Associates, Inc.
(b)	Address or principal business office or, if none, residence: 1307 Point Street, Baltimore, MD 21231
(c)	Citizenship: Maryland
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: G72800108
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	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 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 71047
(b)	Percent of class: 0.1 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 71047
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 71047
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 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.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

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 of 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, other than activities solely in connection with a nomination under ?? 240.14a-11. T. Rowe Price Associates, Inc. hereby declares and affirms that the filing of Schedule 13G shall not be construed as an admission that Price Associates is the beneficial owner of the securities referred to, which beneficial ownership is expressly denied.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

T. Rowe Price Associates, Inc.

Signature:	Ellen York
Name/Title:	Vice President
Date:	08/14/2025

FAQ

How many Prothena (PRTA) shares does T. Rowe Price own?

T. Rowe Price Associates, Inc. reports beneficial ownership of 71,047 shares of Prothena common stock.

What percentage of Prothena does the 71,047-share stake represent?

The filing states the position represents approximately 0.1% of the class of Prothena common stock.

Does T. Rowe Price have voting or dispositive power over these PRTA shares?

Yes. The report shows sole voting power and sole dispositive power for all 71,047 shares.

Was the stake reported as held to influence control of Prothena (PRTA)?

No. The certification states the shares are held in the ordinary course of business and not to change or influence control.

Did the filing indicate group ownership or holdings on behalf of another person?

No. Items related to group membership and ownership on behalf of another person are marked Not Applicable.

Under what reporting classification was this Schedule 13G filed?

The filing identifies the reporting person type as an investment adviser (IA) and is submitted on Schedule 13G.