SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 3)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Sections 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Section 240.13d-7 for other parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

* This calculation is based on 70,744,044 shares of Common Stock, par value $0.0001 per share, outstanding as of July 29, 2016, as reported by the Issuer on its Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2016 filed by the Issuer with the Securities and Exchange Commission on August 5, 2016.

2

* This calculation is based on 70,744,044 shares of Common Stock, par value $0.0001 per share, outstanding as of July 29, 2016, as reported by the Issuer on its Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2016 filed by the Issuer with the Securities and Exchange Commission on August 5, 2016.

3

This Amendment No. 3 (this “Amendment”) amends the Schedule 13D initially filed with the Securities and Exchange Commission on August 4, 2006, as previously amended on September 6, 2006, and December 8, 2015 (the “Original Schedule 13D”) relating to shares of the common stock, par value $.0001 per share (the “Common Stock”), of Momenta Pharmaceuticals, Inc., a Delaware corporation (the “Issuer”). All information reported in the Original Schedule 13D remains in effect except to the extent that it is amended or superseded by information contained in this Amendment.  Capitalized terms used but not defined in this Amendment shall have the respective meanings set forth with respect thereto in the Original Schedule 13D.

This Amendment is being filed by the Reporting Persons to report: (i) a decrease in the number and percentage of issued and outstanding shares of Common Stock beneficially owned by the Reporting Persons resulting from the sale of Common Stock of the Issuer by the Investor pursuant to the Sales Plan (as defined in Item 6); and (ii) certain changes in disclosure responsive to Items 4, 5 and 6 and Schedule I of the Original Schedule 13D, as set forth below.

Item 4.           Purpose of Transaction.

Item 4 of the Original 13D is hereby amended in its entirety as follows:

On August 8, 2016, the Reporting Persons entered into a Sales Plan (as defined in Item 6 below) pursuant to which the Investor has instructed the sale of the shares of Common Stock of the Issuer which it owns, subject to terms and conditions relating to, among other things, the price of such Common Stock.  The term of the Sales Plan ends on January 26, 2017.

Other than as described above, neither of the Reporting Persons have any present plans or proposals which relate to or that would result in any of the actions or transactions described in paragraphs (a) through (j) of Item 4 of the instructions to Schedule 13D. Each Reporting Person reserves the right from time to time to formulate plans or proposals regarding the Issuer or any of its securities and to carry out any of the actions or transactions described in paragraphs (a) through (j) of Item 4 of the instructions to Schedule 13D, to the extent deemed advisable by such Reporting Person.

Item 5.           Interest in Securities of the Issuer.

Items 5(a) – (c) of the Original 13D are amended and restated in their entirety to read as follows:

(a) - (b) The Investor is the record holder and beneficial owner of 4,449,946 shares of the Issuer’s Common Stock. As a result of the Investor’s holdings, Novartis is a beneficial owner of the Securities. Based on publicly available information, the Securities represent approximately 6.29% of the Issuer’s outstanding Common Stock and the Reporting Persons have shared power

4

to vote or direct the vote and shared power to dispose or to direct the disposition of the Securities.

Except as described in this Amendment, neither of the Reporting Persons nor, to the best knowledge of the Reporting Persons, any of the persons identified in Schedule I hereto beneficially owns any additional shares of Common Stock.

(c)          Pursuant to the Sales Plan, the following transactions in the Issuer’s Common Stock were effected by the Investor:

Item 6.           Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Item 6 of the Schedule 13D is hereby amended by adding the following:

On August 8, 2016, the Reporting Persons entered into a 10b5-1 Sales Plan with Novartis International AG (the “Sales Plan”). Under the Sales Plan, beginning on August 8, 2016, and ending on January 26, 2017, Novartis International AG is instructed to sell the shares of Common Stock of the Issuer owned by the Investor, subject to terms and conditions relating to, among other things, the price of such Common Stock.

Item 7.           Materials to be Filed as Exhibits.

5

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

6

Schedule I

DIRECTORS AND EXECUTIVE OFFICERS OF

NOVARTIS AG AND NOVARTIS PHARMA AG

DIRECTORS AND EXECUTIVE OFFICERS OF NOVARTIS AG

The name, function, citizenship and present principal occupation or employment of each of the directors and executive officers of Novartis AG are set forth below. Unless otherwise indicated below, (i) each occupation set forth opposite an individual’s name refers to employment with Novartis AG and (ii) the business address of each director and executive officer of Novartis AG is Novartis Campus, Lichstrasse 35, CH-4056, Basel, Switzerland.

DIRECTORS AND EXECUTIVE OFFICERS OF NOVARTIS PHARMA AG

The name, function, citizenship and present principal occupation or employment of each of the directors and executive officers of Novartis Pharma AG are set forth below. Unless otherwise indicated below, (i) each occupation set forth opposite an individual’s name refers to employment with Novartis Pharma AG and (ii) the business address of each director and executive officer of Novartis Pharma AG is Novartis Campus, Lichstrasse 35, CH-4056, Basel, Switzerland.

EXHIBIT INDEX