13G Filing: Billionaire David Shaw’s D. E. Shaw & Co. and AMAG Pharmaceuticals Inc. (AMAG)

D. E. Shaw Co., a fund founded by billionaire quant David Shaw, has disclosed its position in AMAG Pharmaceuticals, Inc. (NASDAQ:AMAG) in a recent filing with the Securities and Exchange Commission. According to the 13G filing, D. E. Shaw owns 1.73 million shares of AMAG, which represent 5.0% of the company’s outstanding stock. The position is passive by nature.

You can access the original SEC filing by clicking here.

Ownership Summary Table

Page 1 of 6 SEC Filing

Page 2 of 6 SEC Filing

CUSIP No. 00163U106
	1.	Names of Reporting Persons I.R.S. Identification Nos. of above persons (entities only) D. E. Shaw & Co., L.P. 13-3695715
	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 Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power -0-
			6.		Shared Voting Power 1,729,526
			7.		Sole Dispositive Power -0-
			8.		Shared Dispositive Power 1,735,509
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,735,509
	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o
	11.	Percent of Class Represented by Amount in Row (9) 5.0%
	12.	Type of Reporting Person (See Instructions) IA, PN

Page 3 of 6 SEC Filing

CUSIP No. 00163U106
	1.	Names of Reporting Persons I.R.S. Identification Nos. of above persons (entities only) David E. Shaw
	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 United States
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power -0-
			6.		Shared Voting Power 1,729,526
			7.		Sole Dispositive Power -0-
			8.		Shared Dispositive Power 1,735,509
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,735,509
	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o
	11.	Percent of Class Represented by Amount in Row (9) 5.0%
	12.	Type of Reporting Person (See Instructions) IN

Page 4 of 6 SEC Filing

Item 1.
	(a)	Name of Issuer
		AMAG Pharmaceuticals, Inc.
	(b)	Address of Issuer’s Principal Executive Offices
		1100 Winter Street
		Waltham, Massachusetts 02451
Item 2.
	(a)	Name of Person Filing
		D. E. Shaw & Co., L.P.
		David E. Shaw
	(b)	Address of Principal Business Office or, if none, Residence
		The business address for each reporting person is:
		1166 Avenue of the Americas, 9th Floor
		New York, NY 10036
	(c)	Citizenship
		D. E. Shaw & Co., L.P. is a limited partnership organized under the laws of the state of Delaware.
		David E. Shaw is a citizen of the United States of America.
	(d)	Title of Class of Securities
		Common Stock, par value $0.01
	(e)	CUSIP Number
		00163U106

Item 3.	If this statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) or (c), check whether the person filing is a:
Not Applicable
Item 4.	Ownership

As of January 4, 2016:

(a)

Amount beneficially owned:

D. E. Shaw & Co., L.P.:	1,735,509 shares This is composed of (i) 1,051,098 shares in the name of D. E. Shaw Valence Portfolios, L.L.C., (ii) 597,677 shares in the name of D. E. Shaw Oculus Portfolios, L.L.C., (iii) 1,500 shares in the name of D. E. Shaw Heliant Capital, L.L.C., and (iv) 85,234 shares under the management of D. E. Shaw Investment Management, L.L.C.
David E. Shaw:	1,735,509 shares This is composed of (i) 1,051,098 shares in the name of D. E. Shaw Valence Portfolios, L.L.C., (ii) 597,677 shares in the name of D. E. Shaw Oculus Portfolios, L.L.C., (iii) 1,500 shares in the name of D. E. Shaw Heliant Capital, L.L.C., and (iv) 85,234 shares under the management of D. E. Shaw Investment Management, L.L.C.

Page 5 of 6 SEC Filing

(b)

Percent of class:

D. E. Shaw & Co., L.P.:	5.0%
David E. Shaw:	5.0%

(c)

Number of shares to which the person has:

(i)

Sole power to vote or to direct the vote:

D. E. Shaw & Co., L.P.:	-0- shares
David E. Shaw:	-0- shares

(ii)

Shared power to vote or to direct the vote:

D. E. Shaw & Co., L.P.:	1,729,526 shares
David E. Shaw:	1,729,526 shares

(iii)

Sole power to dispose or to direct the disposition of:

D. E. Shaw & Co., L.P.:	-0- shares
David E. Shaw:	-0- shares

(iv)

Shared power to dispose or to direct the disposition of:

D. E. Shaw & Co., L.P.:	1,735,509 shares
David E. Shaw:	1,735,509 shares

David E. Shaw does not own any shares directly. By virtue of David E. Shaw’s position as President and sole shareholder of D. E. Shaw & Co., Inc., which is the general partner of D. E. Shaw & Co., L.P., which in turn is the manager and investment adviser of D. E. Shaw Valence Portfolios, L.L.C., the investment
adviser of D. E. Shaw Oculus Portfolios, L.L.C., and the managing member of (i) D. E. Shaw Investment Management, L.L.C., and (ii)
D. E. Shaw Heliant Adviser, L.L.C., which in turn is the investment adviser of D. E. Shaw Heliant Capital, L.L.C., and by virtue
of David E. Shaw’s position as President and sole shareholder of D. E. Shaw & Co. II, Inc., which is the managing member
of D. E. Shaw & Co., L.L.C., which in turn is the manager of D. E. Shaw Oculus Portfolios, L.L.C. and the managing
member of (i) D. E. Shaw Heliant Manager, L.L.C., which in turn is the manager of D. E. Shaw Heliant Capital, L.L.C., David E. Shaw may be deemed to have the shared power to vote or direct the vote of 1,729,526 shares, and the shared power to dispose or
direct the disposition of 1,735,509 shares, the 1,735,509 shares as described above constituting 5.0% of the outstanding shares
and, therefore, David E. Shaw may be deemed to be the beneficial owner of such shares. David E. Shaw disclaims beneficial
ownership of such 1,735,509 shares.

Item 5.	Ownership of Five Percent or Less of a Class
Not Applicable
Item 6.	Ownership of More than Five Percent on Behalf of Another Person.
Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.
Not Applicable
Item 8.	Identification and Classification of Members of the Group
Not Applicable
Item 9.	Notice of Dissolution of Group
Not Applicable
Item 10.	Certification

By signing below, each of D. E. Shaw & Co., L.P.
and David E. Shaw certify that, to the best of such reporting person’s 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 such
purposes or effect.

 

Page 6 of 6 SEC Filing

 

SIGNATURE

After reasonable inquiry and to the best of their knowledge and
belief, the undersigned certify that the information set forth in this statement is true, complete and correct. A Power of Attorney,
dated December 16, 2014, granted by David E. Shaw in favor of Nathan Thomas, is attached hereto.

Dated: January 14, 2016

	D. E. Shaw & Co., L.P.
	By:	/s/ Nathan Thomas
		Nathan Thomas
		Chief Compliance Officer
	David E. Shaw
	By:	/s/ Nathan Thomas
		Nathan Thomas
		Attorney-in-Fact for David E. Shaw