Edgar Filing: INFINITY PHARMACEUTICALS, INC.

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

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(Print or Type Responses)

1. Name and Address of Reporting Person ^*

TANANBAUM JAMES B

2. Issuer Name and Ticker or Trading Symbol
INFINITY PHARMACEUTICALS, INC. [INFI]

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 PROSPECT VENTURE PARTNERS, 435 TASSO STREET, SUITE 200

3. Date of Earliest Transaction (Month/Day/Year)
09/12/2006

(Street)

PALO ALTO, CA 94301

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)
1.Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	09/12/2006		A		134,688 ⁽¹⁾	A	⁽²⁾	134,688 ⁽¹⁾	I	By Tananbaum Family Trust
Common Stock	09/12/2006		A		107,750 ⁽¹⁾ ⁽³⁾	A	⁽⁴⁾	107,750 ⁽¹⁾	I	By Prospect Venture Partners II, L.P.
Common Stock	09/12/2006		A		510,575 ⁽¹⁾ ⁽³⁾	A	⁽⁵⁾	510,575 ⁽¹⁾	I	By Prospect Venture Partners II, L.P.
Common Stock	09/12/2006		A		799,152 ⁽¹⁾ ⁽³⁾	A	⁽⁶⁾	799,152 ⁽¹⁾	I	By Prospect Venture Partners II, L.P.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Stock Option (right to buy)

$ 15.04 ⁽¹⁾

09/12/2006

28,125 ⁽¹⁾

⁽⁷⁾

09/12/2016

Common Stock

28,125 ⁽¹⁾

$ 0

28,125 ⁽¹⁾

Stock Option (right to buy)

$ 15.04 ⁽¹⁾

09/12/2006

1,875 ⁽¹⁾

⁽⁸⁾

09/12/2016

Common Stock

1,875 ⁽¹⁾

$ 0

1,875 ⁽¹⁾

Reporting Owners

Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
TANANBAUM JAMES B C/O PROSPECT VENTURE PARTNERS 435 TASSO STREET, SUITE 200 PALO ALTO, CA 94301	X

Signatures

/s/ James B. Tananbaum		09/13/2006
^**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)	Reflects a 1-for-4 reverse stock split, which became effective on September 12, 2006.
(2)	Received in exchange for 609,375 shares of Infinity Discovery, Inc. ("IPI") common stock in connection with the merger of IPI into Infinity Pharmaceuticals, Inc. (the "Merger") based on a conversion ratio of 0.88411.
(3)	The reporting person is a managing member of the general partner of the partnership that owns the reported securities. The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein.
(4)	Received in exchange for 487,500 shares of IPI common stock in connection with the Merger based on a conversion ratio of 0.88411.
(5)	Received in exchange for 2,600,000 shares of IPI Series A Preferred Stock in connection with the Merger based on a conversion ratio of 0.78550. The Series A Preferred Stock had no expiration date.
(6)	Received in exchange for 3,200,000 shares of IPI Series B Preferred Stock in connection with the Merger based on a conversion ratio of 0.99894. The Series B Preferred Stock had no expiration date.
(7)	The option vests as to 9,375 of the shares on the first anniversary of the grant date, which grant date was September 12, 2006, and the remainder in quarterly installments of 2,343 shares beginning at the end of the first quarter thereafter, provided that the holder continues to serve as a director.
(8)	The option vests in quarterly installments of 468 shares beginning at the end of the first quarter after the date of grant, which grant date was September 12, 2006, provided that the holder continues to serve as the chairman of the corporate governance committee of the board of directors.

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