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 *
FLEMING JONATHAN
  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
_____ Officer (give title below) _____ Other (specify below)
(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   15,173 A (1) 15,173 I By fund (2)
Common Stock 05/17/2011   A   151 A (3) 15,324 I By fund (4)

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
Series A-2 Convertible Preferred Stock (5) 05/17/2011   A   108,628   05/17/2011   (5) Common Stock 1,086,280 (6) 108,628 I By Fund (2)
Series A-2 Convertible Preferred Stock (5) 05/17/2011   A   1,090   05/17/2011   (5) Common Stock 10,900 (7) 109,718 I By Fund (4)
Series A-3 Convertible Preferred Stock (8) 05/17/2011   A   24,983   05/17/2011   (8) Common Stock 249,830 (9) 24,983 I By Fund (2)
Series A-3 Convertible Preferred Stock (8) 05/17/2011   A   250   05/17/2011   (8) Common Stock 2,500 (10) 25,233 I By Fund (4)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
FLEMING JONATHAN
C/O RADIUS HEALTH
INC. 201 BROADWAY, 6TH FLOOR
CAMBRIDGE, MA 02139
  X      

Signatures

 /s/ B. Nicholas Harvey, attorney-in-fact   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 15,173 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) The reported securities are owned directly by OBP IV - Holdings LLC ("OBP IV") and indirectly by Oxford Bioscience Partners IV L.P. ("OBP LP"), a member of OBP IV, and OBP Management IV L.P. ("OBP Management IV"), the sole general partner of OBP LP. Jonathan Fleming is one of two individual general partners of OBP Management IV. Mr. Fleming disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
(3) Received in exchange for 151 shares of common stock of Radius Health, Inc. in connection with the Merger.
(4) The reported securities are owned directly by mRNA II - Holdings LLC ("mRNA II") and indirectly by mRNA Fund II ("mRNA LP"), a member of mRNA II, and OBP Management IV L.P. ("OBP Management IV"), the sole general partner of mRNA LP. Jonathan Fleming is one of two individual general partners of OBP Management IV. Mr. Fleming disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
(5) The Series A-2 convertible preferred stock is convertible into common stock at any time on a one-for-ten basis, and has no expiration date.
(6) Received in exchange for 1,086,280 shares of Series A-2 convertible preferred stock of Radius Health, Inc. in connection with the Merger.
(7) Received in exchange for 10,900 shares of Series A-2 convertible preferred stock of Radius Health, Inc. in connection with the Merger.
(8) The Series A-3 convertible preferred stock is convertible into common stock at any time on a one-for-ten basis, and has no expiration date.
(9) Received in exchange for 249,830 shares of Series A-3 convertible preferred stock of Radius Health, Inc. in connection with the Merger.
(10) Received in exchange for 2,500 shares of Series A-3 convertible preferred stock of Radius Health, Inc. 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.