REPLIGEN CORP — Director's Dealing 2014

May 19, 2014

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: REPLIGEN CORP (RGEN)
CIK: 0000730272
Period of Report: 2014-05-15

Reporting Person: GRIFFITH MICHAEL A (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2014-05-15	Common Stock	A	1932	—	Acquired	9274	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2014-05-15	Stock Option (Right to Buy)	$18.12	A	3696	Acquired	2024-05-15	Common Stock (3696)	Direct

Footnotes

F1: Mr. Griffith was awarded 1,932 Restricted Stock Units. Each Restricted Stock Unit represents a contingent right to receive one share of Repligen Corporation's Common Stock. The Restricted Stock Units vest on May 15, 2015. The Restricted Stock Units may be settled only by delivering shares of Repligen Corporation's Common Stock, and thus, the grant is being reported in Table 1 as allowed per SEC guidance.

F2: Award vests in full one year from grant date on May 15, 2015.