Sanofi — Major Shareholding Notification 2012

Apr 2, 2012

SC 13G 1 d326677dsc13g.htm SCHEDULE 13G Schedule 13G

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934*

Merrimack Pharmaceuticals, Inc

(Name of Issuer)

COMMON STOCK, $ 0.01 PAR VALUE

(Title of Class of Securities)

590328100

(CUSIP Number)

March 29, 2012

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1 (b)

x Rule 13d-1 (c)

¨ Rule 13d-1 (d)

• 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 the disclosures provided in a prior cover page.

The information required in 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 to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(Continued on following pages)

CUSIP NO. 590328100

| 1. | NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Sanofi | | | --- | --- | --- | | 2. | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) ¨ (b) ¨ | | | 3. | SEC USE ONLY | | | 4. | CITIZENSHIP OR PLACE OF ORGANIZATION The Republic of France | | | Number of Shares Beneficially Owned by Each Reporting Person With: | 5. | SOLE VOTING POWER 5,217,391 shares | | | 6. | SHARED VOTING POWER 0 shares | | | 7. | SOLE DISPOSITIVE POWER 5,217,391 shares | | | 8. | SHARED DISPOSITIVE POWER 0 shares | | 9. | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,217,391 shares | | | 10. | CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) ¨ | | | 11. | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.65% | | | 12. | TYPE OF REPORTING PERSON (see instructions) CO. | |

Item 1(a). Name of Issuer:

Merrimack Pharmaceuticals, Inc.

Item 1(b). Address of Issuer’s Principal Executive Offices:

One Kendall Square, Suite B7201, Cambridge, Massachusetts 02139

Item 2(a). Name of Person Filing:

Sanofi

Item 2(b). Address of Principal Business Office, or if none, Residence:

54, rue La Boétie, 75008 Paris, France

Item 2(c). Citizenship:

The Republic of France

Item 2(d). Title of Class of Securities:

COMMON STOCK, $ 0.01 PAR VALUE

Item 2(e). CUSIP Number:

590328100

ITEM 3. Item 3 is not applicable.

Item 4(a). Amount Beneficially Owned:

5,217,391 shares

Item 4(b). Percent of Class:

5.65%

Item 4(c). Number of shares as to which such person has:

(i) Sole power to vote or to direct the vote:

5,217,391 shares

(ii) Shared power to vote or to direct the vote:

0 shares

(iii) Sole power to dispose or to direct the disposition of:

5,217,391 shares

(iv) Shared power to dispose or to direct the disposition of:

0 shares

ITEM 5. Ownership of Five Percent or Less of a Class:

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following ¨ .

ITEM 6. Ownership of More than Five Percent on Behalf of Another Person:

Item 6 is not applicable.

ITEM 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company:

Item 7 is not applicable.

ITEM 8. Identification and Classification of Members of a Group:

Item 8 is not applicable.

ITEM 9. Notice of Dissolution of Group:

Item 9 is not applicable.

ITEM 10. Certification:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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.

/s/ John FELITTI
John FELITTI
Associate Vice President
Corporate Law, Financial & Securities Law