Statement of Changes in Beneficial Ownership (4)

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	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Arroyo Santiago	2. Issuer Name and Ticker or Trading Symbol MOMENTA PHARMACEUTICALS INC [ MNTA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                      _____ 10% Owner __ X __ Officer (give title below)      _____ Other (specify below) SVP, Chief Medical Officer
(Last)          (First)          (Middle) C/O MOMENTA PHARMACEUTICALS, INC., 675 WEST KENDALL STREET	3. Date of Earliest Transaction (MM/DD/YYYY) 6/20/2017
(Street) CAMBRIDGE, MA 02142 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	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 Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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	6/20/2017		A (1)		36000	A	$0	36000	D

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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)	$17.20	6/20/2017		A		150000   (2)		(3)	6/20/2027	Common Stock	150000	$0	150000	D

Explanation of Responses:
(1)	Represents 36,000 shares of restricted common stock, $0.0001 par value per share, awarded pursuant to the Company's 2013 Incentive Award Plan, as amended and restated, and subject to a restricted stock agreement to be entered into between the Company and Dr. Arroyo. Pursuant to the restricted stock agreement, the shares of restricted common stock shall vest on the achievement of certain company goals within a specified time period.
(2)	Represents options granted by the issuer pursuant to the issuer's 2013 Incentive Award Plan.
(3)	The stock option will vest and become exercisable with respect to 37,500 shares on the first anniversary of the grant date, and the remainder will vest in equal quarterly installments over the subsequent three years. All vesting is subject to Dr. Arroyo's continued service to the Company through the applicable vesting date.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Arroyo Santiago C/O MOMENTA PHARMACEUTICALS, INC. 675 WEST KENDALL STREET CAMBRIDGE, MA 02142			SVP, Chief Medical Officer

Signatures
/s/ Andrea Paul as attorney in fact		6/22/2017
** 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 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 control number.