Prothena (PRTA) Form 3 Initial statement of insider ownership

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

EcoR1 Capital, LLC

(Last) (First) (Middle)

357 TEHAMA STREET #3

(Street)

SAN FRANCISCO CA 94103

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
08/23/2019

3. Issuer Name and Ticker or Trading Symbol
Prothena Corp plc [ PRTA ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

Director	X	10% Owner
Officer (give title below)		Other (specify below)

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Ordinary Shares	9,426,640	I	See Note(1)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The filing persons (the "Filers") are EcoR1 Capital, LLC ("EcoR1"), Oleg Nodelman and EcoR1 Capital Fund Qualified, L.P. ("Qualified Fund"). EcoR1 is the general partner and investment adviser of private funds, including Qualified Fund (collectively, the "Funds"). Mr. Nodelman is the manager and controlling owner of EcoR1. EcoR1 is filing this Form 3 for itself, Mr. Nodelman and Qualified Fund. The Filers are filing this Form 3 jointly, but not as a group, and each expressly disclaims membership in a group, within the meaning of Rule 13d-5(b) under the Securities Exchange Act of 1934, as amended. The Funds hold these securities directly for the benefit of their investors. EcoR1 indirectly beneficially owns them as the investment adviser to the Funds, and Mr. Nodelman indirectly beneficially owns them as the control person of EcoR1. The Filers disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein.

	EcoR1 Capital, LLC, By Oleg Nodelman, Manager	08/23/2019
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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