Ownership Submission
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 *
Terifay Robert J
   2. Issuer Name and Ticker or Trading Symbol
REGENERON PHARMACEUTICALS INC [REGN] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
SVP Commercial
(Last)
(First)
(Middle)
777 OLD SAW MILL RIVER ROAD		 3. Date of Earliest Transaction (Month/Day/Year)
05/07/2013
(Street)

TARRYTOWN, NY 10591		 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
Common Stock 05/07/2013   M   14,750 A $ 16.8 30,074 D  
Common Stock 05/07/2013   F   946 D $ 261.67 29,128 D  
Common Stock 05/07/2013   F   6,857 D $ 261.67 22,271 D  
Common Stock 05/07/2013   M   2,173 A $ 16.8 24,444 D  
Common Stock 05/07/2013   F   139 D $ 261.67 24,305 D  
Common Stock 05/07/2013   F   750 D $ 261.67 23,555 D  
Common Stock 05/08/2013   S   3,394 D $ 260.86 (1) 20,161 D  
Common Stock 05/08/2013   S   4,437 D $ 261.44 (2) 15,724 D  
Common Stock 05/08/2013   S   400 D $ 262.06 (3) 15,324 D  
Common Stock               1,588 I By 401(k) Plan

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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
Non-Qualified Stock Option (right to buy) $ 16.8 05/07/2013   M     14,750 12/31/2011(4) 12/17/2018 Common Stock 14,750 (5) 2,173 D  
Non-Qualified Stock Option (right to buy) $ 16.8 05/07/2013   M     2,173   (6) 12/17/2018 Common Stock 2,173 (5) 0 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Terifay Robert J
777 OLD SAW MILL RIVER ROAD
TARRYTOWN, NY 10591		       SVP Commercial  

Signatures

 /s/**Robert J. Terifay   05/09/2013
**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) Represents volume-weighted average price of sales of 3,394 shares of Company stock on May 8, 2013 at prices ranging from $260.58 to $260.99. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 8, 2013 at each separate price.
(2) Represents volume-weighted average price of sales of 4,437 shares of Company stock on May 8, 2013 at prices ranging from $261.01 to $261.98. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 8, 2013 at each separate price.
(3) Represents volume-weighted average price of sales of 400 shares of Company stock on May 8, 2013 at prices ranging from $262.03 to $262.13. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 8, 2013 at each separate price.
(4) On December 17, 2008, the reporting person was granted an option to purchase 48,750 shares of Common Stock. The option was eligible to vest, partially or in full, on December 31, 2011, based on the extent to which the company satisfied certain performance criteria. The performance criteria were met and the option vested as to all shares.
(5) Exercisable date, exercise date, exercise price, purchase price, sales price, and/or expiration date is/are not applicable in this case.
(6) The stock option award (combined incentive stock option and non-qualified stock option) vests in four equal annual installments, commencing one year after the date of grant.

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