Insider filing report for Changes in Beneficial Ownership
"Insiders might sell their shares for any number of reasons, but they buy them for only one: they think the price will rise"
- Peter Lynch
What is insider trading>>
The following is an SEC EDGAR document rendered as filed.
Here is the list of insider trading transaction codes

FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP
Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Expires: November 30, 2011
Estimated average burden hours per response... 0.5
1. Name and Address of Reporting Person *
Ong Tuyen
2. Issuer Name and Ticker or Trading Symbol
Nightstar Therapeutics plc [ NITE]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
X __ Officer (give title below) _____ Other (specify below)
Chief Development Officer
(Last)
(First)
(Middle)
C/O NIGHTSTAR, INC., 203 CRESCENT STREET, SUITE 303
3. Date of Earliest Transaction (MM/DD/YY)
06/07/2019
(Street)
WALTHAM, MA02453
4. If Amendment, Date Original Filed (MM/DD/YY)
6. Individual or Joint/Group Filing (Check Applicable Line)
__ X __ Form filed by One Reporting Person
_____ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Ordinary Shares ( 1 ) 06/07/2019 D 80,479 D $ 25.5 0 D
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(MM/DD/YY)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Option (Right to Buy) $ 14.24 06/07/2019 D 37,500 ( 2 ) 01/30/2028 Ordinary Shares ( 1 ) 37,500 $ 11.26 ( 3 ) 0 D
Stock Option (Right to Buy) $ 14.74 06/07/2019 D 97,400 ( 2 ) 01/21/2019 Ordinary Shares ( 1 ) 97,400 $ 10.76 ( 3 ) 0 D
Reporting Owners
Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Ong Tuyen
C/O NIGHTSTAR, INC.
203 CRESCENT STREET, SUITE 303
WALTHAM, MA02453
Chief Development Officer
Signatures
/s/ Bryan Yoon, Attorney-in-Fact 06/07/2019
** Signature of Reporting Person Date
Explanation of Responses:
( 1 )The ordinary shares, nominal value GBP 0.01 per share, of Nightstar Therapeutics plc (the "Issuer") may be represented by American Depositary Shares ("ADSs"). Each ADS represents one ordinary share of the Issuer.
( 2 )In connection with the acquisition by Tungsten Bidco Limited of the entire issued and to be issued share capital of the Issuer on June 7, 2019 by means of a scheme of arrangement under Part 26 of the UK Companies Act 2006, all stock options were cancelled in exchange for a payment equal to $25.50 with respect to each ordinary share subject to the option award, less the applicable exercise price.
( 3 )Represents the payment per share received in exchange for the cancellation of each option of $25.50, less the applicable exercise price.

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 4(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).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.