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 OF SECURITIES 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

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(Print or Type Responses)

1. Name and Address of Reporting Person * EDDLEMAN ROY T   2. Issuer Name and Ticker or Trading Symbol REPLIGEN CORP [RPGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O TROYGOULD PC, 1801 CENTURY PARK E., 16TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 07/12/2018 (Street) LOS ANGELES, CA 90067 4. If Amendment, Date 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 (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

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 (Month/Day/Year)

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

Call option (obligation to sell)

$ 54.9298

07/12/2018

S

1 (1)

01/13/2020

01/13/2020

Common Stock

250,000

$ 1,000,000

1

I

As trustee (2)

Put option (right to sell) (1)

$ 43.4992

07/12/2018

P

1

01/13/2020

01/13/2020

Common Stock

250,000

$ 1,000,000

1

I

As trustee (2)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
EDDLEMAN ROY T C/O TROYGOULD PC 1801 CENTURY PARK E., 16TH FLOOR LOS ANGELES, CA 90067		X

Signatures

Istvan Benko, as Attorney-in-Fact for Roy T. Eddleman		07/16/2018
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The reporting person entered into a so-called zero-cost collar arrangement pursuant to which he wrote a covered call option and purchased a put option. Only one of the options can be "in the money" on the expiration date, at which time the in-the-money option will be exercised (and settled in cash) and the other option will expire. If neither option is in the money on the expiration date, both will expire.
(2)	The securities shown are held of record by the Roy T. Eddleman Living Trust UAD 8-7-2000, of which the reporting person is the sole trustee, and as such, has investment and voting control over such securities.

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