Ownership Submission
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

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Expires: January 31, 2005
Estimated average burden hours per response... 0.5

(Print or Type Responses)
1. Name and Address of Reporting Person *
Lyttle Cecil Richard
   2. Issuer Name and Ticker or Trading Symbol
Radius Health, Inc. [NONE] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
President and C.E.O.
(Last)
(First)
(Middle)
C/O RADIUS HEALTH, INC., 201 BROADWAY, 6TH FLOOR		 3. Date of Earliest Transaction (Month/Day/Year)
05/17/2011
(Street)

CAMBRIDGE, MA 02139		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction 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 05/17/2011   A   66,666 A (1) 66,666 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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. SEC 1474 (9-02)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction 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
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(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) $ 1.5 05/17/2011   A   108,333     (2) 10/28/2014 Common Stock 108,333 (3) 108,333 D  
Stock Option (Right to Buy) $ 0.9 05/17/2011   A   91,846     (4) 07/12/2017 Common Stock 91,846 (5) 91,846 D  
Stock Option (Right to Buy) $ 1.2 05/17/2011   A   202,672     (6) 05/08/2018 Common Stock 202,672 (7) 202,672 D  
Stock Option (Right to Buy) $ 1.2 05/17/2011   A   86,376     (8) 12/03/2018 Common Stock 86,376 (9) 86,376 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Lyttle Cecil Richard
C/O RADIUS HEALTH, INC.
201 BROADWAY, 6TH FLOOR
CAMBRIDGE, MA 02139		   X     President and C.E.O.  

Signatures

 /s/ C. Richard Lyttle   05/19/2011
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) Received in exchange for 66,666 shares of common stock of Radius Health, Inc. in connection with the merger of RHI Merger Corp., a wholly-owned subsidiary of the Registrant (f/k/a MPM Acquisition Corp.), with and into Radius Health, Inc. ("Target") pursuant to which Target survived and became a wholly-owned subsidiary of Registrant (the "Surviving Corporation"). Following such merger, the Surviving Corporation merged with and into its parent corporation, the Registrant, and subsequently changed its name to "Radius Health, Inc." (the "Merger").
(2) Twenty-five percent of the options vested on September 1, 2005, an additional twenty-five percent vested in twelve equal quarterly installments with the first quarterly installment vesting on January 1, 2006, and the additional quarterly installments vested on the first day of each calendar quarter thereafter. The remaining fifty percent of the options vest on or prior to September 1, 2009 upon the completion of certain milestones.
(3) Received in exchange for employee stock options to acquire 108,333 shares of Radius Health, Inc. common stock for $1.50 per share in connection with the Merger.
(4) 62,744 of the options vested on July 12, 2007, an additional 16,511 options vested over five equal quarterly installments with the first quarterly installment vesting on October 1, 2007 and the remaining options vest on the achievement of certain milestones.
(5) Received in exchange for employee stock options to acquire 91,846 shares of Radius Health, Inc. common stock for $0.90 per share in connection with the Merger.
(6) 97,113 of the options vested on May 8, 2008, an additional 4,222 of the options vested on October 1, 2008, and the remaining options vest on the achievement of certain milestones.
(7) Received in exchange for employee stock options to acquire 202,672 shares of Radius Health, Inc. common stock for $1.20 per share in connection with the Merger.
(8) 43,188 of the options vested on December 3, 2008 and the remaining options vest on the achievement of certain milestones.
(9) Received in exchange for employee stock options to acquire 86,376 shares of Radius Health, Inc. common stock for $1.20 per share in connection with the Merger.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.