Under the Securities Exchange Act of 1934
(Amendment No. 2)*

(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 68,997,260 shares of Common Stock, par value $0.0001 per share, outstanding as of October 30, 2015, as reported by the Issuer on its Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2015, filed by the Issuer with the Securities and Exchange Commission on November 6, 2015.

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* This calculation is based on 68,997,260 shares of Common Stock, par value $0.0001 per share, outstanding as of October 30, 2015, as reported by the Issuer on its Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2015, filed by the Issuer with the Securities and Exchange Commission on November 6, 2015.

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This Amendment No. 2 (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 (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 percentage of outstanding Common Stock beneficially owned by the Reporting Persons resulting solely from an increase in the number of Common Stock of the Issuer issued and outstanding; (ii) certain changes in disclosure responsive to Item 2 of the Original Schedule 13D, as set forth below; (iii) certain changes in disclosure responsive to Item 5 of the Original Schedule 13D, as set forth below; and (iv) changes to the executive officers and directors of the Reporting Persons, as set forth in Schedule I hereto.

Item 2.           Security and Issuer.

Items 2(a) - (c) and (f) of the Original 13D are amended and restated in their entirety to read as follows:

(a) - (c); (f)   Novartis Pharma AG (the “Investor”) is a corporation organized under the laws of Switzerland and is a wholly-owned subsidiary of Novartis AG.  The Investor is principally engaged in the research and development, production and worldwide marketing of pharmaceuticals.

Novartis AG (“Novartis”) is a corporation organized under the laws of Switzerland and is the publicly owned parent of a multinational group of companies specializing in the research, development, manufacturing and marketing of a broad range of healthcare products, led by innovative pharmaceuticals. Novartis is the 100% owner of the Investor.

Novartis and the Investor are collectively referred to herein as the “Reporting Persons”.

The name, function, business address, citizenship and present principal occupation of the executive officers and members of the Board of Directors of the Reporting Persons is set forth on Schedule I hereto and incorporated herein by reference.

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:

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(a) - (c) The Investor is the record holder and beneficial owner of 4,708,679 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 6.82% of the Issuer’s outstanding Common Stock and the Reporting Persons have shared power 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 (i) beneficially owns any additional shares of Common Stock or (ii) has effected any transactions in the shares of Common Stock in the past sixty days.

Item 7.           Materials to be Filed as Exhibits.

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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.

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Schedule I

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 OF NOVARTIS PHARMA AG

The name, function, citizenship and present principal occupation or employment of each of the directors 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 of Novartis Pharma AG is Novartis Campus, Lichstrasse 35, CH-4056, Basel, Switzerland.

EXHIBIT INDEX