jf13g-immunogen_ziff.htm
 
 
   
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C.  20549
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SCHEDULE 13G

 
 
Under the Securities Exchange Act of 1934
 

ImmunoGen, Inc.
(Name of Issuer)
 
Common Stock, Par Value $.01 Per Share
(Title of Class of Securities)
 
45253H101
(CUSIP Number)
 

June 20, 2008
(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)
 
ý 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 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 subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).
 
 
 

 
CUSIP No. 45253H101
13G
Page 2 of 10 Pages


   
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
Ziff Asset Management, L.P.
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)                                                                                                      (a) o
                                                                                                           (b) o
 
3
SEC USE ONLY
 
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION
 
Delaware
 
NUMBER OF
 
SHARES
5
SOLE VOTING POWER
 
0
 
BENEFICIALLY
 
OWNED BY
6
SHARED VOTING POWER
 
7,812,500
 
EACH
 
REPORTING
7
SOLE DISPOSITIVE POWER
 
0
 
PERSON
 
WITH
8
SHARED DISPOSITIVE POWER
 
7,812,500
 
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
7,812,500
 
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)
 
15.4%
 
12
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
 
PN
 
 
 

 
CUSIP No. 45253H101
13G
Page 3 of 10 Pages


   
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
PBK Holdings, Inc.
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)                                                                                                     (a) o
                                                                                                                  (b) o
 
3
SEC USE ONLY
 
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION
 
Delaware
 
NUMBER OF
 
SHARES
5
SOLE VOTING POWER
 
0
 
BENEFICIALLY
 
OWNED BY
6
SHARED VOTING POWER
 
7,812,500
 
EACH
 
REPORTING
7
SOLE DISPOSITIVE POWER
 
0
 
PERSON
 
WITH
8
SHARED DISPOSITIVE POWER
 
7,812,500
 
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
7,812,500
 
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)
 
15.4%
 
12
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
 
CO
 
 
 

 
CUSIP No. 45253H101
13G
Page 4 of 10 Pages


   
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
Philip B. Korsant
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)                                                                                                      (a) o
                                                                                                   (b) o
 
3
SEC USE ONLY
 
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION
 
United States of America
 
NUMBER OF
 
SHARES
5
SOLE VOTING POWER
 
0
 
BENEFICIALLY
 
OWNED BY
6
SHARED VOTING POWER
 
7,812,500
 
EACH
 
REPORTING
7
SOLE DISPOSITIVE POWER
 
0
 
PERSON
 
WITH
8
SHARED DISPOSITIVE POWER
 
7,812,500
 
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
7,812,500
 
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)
 
15.4%
 
12
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
 
IN
 
 

 
CUSIP No. 45253H101
13G
Page 5 of 10 Pages


   
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
ZBI Equities, L.L.C.
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)                                                    (a) o
                                                                                                 (b) o
 
3
SEC USE ONLY
 
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION
 
Delaware
 
NUMBER OF
 
SHARES
5
SOLE VOTING POWER
 
0
 
BENEFICIALLY
 
OWNED BY
6
SHARED VOTING POWER
 
7,812,500
 
EACH
 
REPORTING
7
SOLE DISPOSITIVE POWER
 
0
 
PERSON
 
WITH
8
SHARED DISPOSITIVE POWER
 
7,812,500
 
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
7,812,500
 
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)
 
15.4%
 
12
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
 
IA
 
 
 
 
 
Item 1. (a)      Name of Issuer

ImmunoGen, Inc.

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

830 Winter Street
Waltham, MA 02451

Item 2.(a)        Name of Person Filing

This Schedule 13G is being filed on behalf of the following persons (the “Reporting Persons”)*:

(i)
Ziff Asset Management, L.P. (“ZAM”);
(ii)
PBK Holdings, Inc. (“PBK”);
(iii)
Philip B. Korsant; and
(iv)
ZBI Equities, L.L.C. (“ZBI”).

*Attached as Exhibit A is a copy of an agreement among the Reporting Persons that this Schedule 13G is being filed on behalf of each of them.

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

Ziff Asset Management, L.P.
283 Greenwich Avenue
Greenwich, CT  06830

PBK Holdings, Inc.
283 Greenwich Avenue
Greenwich, CT  06830

Philip B. Korsant
283 Greenwich Avenue
Greenwich, CT  06830

ZBI Equities, L.L.C.
283 Greenwich Avenue
Greenwich, CT  06830

Item 2.(c)          Citizenship

See Item 4 of the attached cover pages.

Item 2.(d)          Title of Class of Securities

Common stock, par value $.01 per share (the “Common Shares”)

Item 2.(e)          CUSIP Number

45253H101

Item 3.

Not applicable as this Schedule 13G is filed pursuant to Rule 13d-1(c).

Item 4.               Ownership
 
(a)
Amount beneficially owned:
   
 
See Item 9 of the attached cover pages.
   
(b)
Percent of class:
   
 
See Item 11 of the attached cover pages.
   
(c)
Number of shares as to which such person has:
     
 
(i)
Sole power to vote or to direct the vote:
     
   
See Item 5 of the attached cover pages.
     
 
(ii)
Shared power to vote or to direct the vote:
     
   
See Item 6 of the attached cover pages.
     
 
(iii)
Sole power to dispose or to direct the disposition:
     
   
See Item 7 of the attached cover pages.
     
 
(iv)
Shared power to dispose or to direct the disposition:
     
   
See Item 8 of the attached cover pages.

Philip B. Korsant shares voting and dispositive power over the shares of Common Stock that he beneficially owns with ZAM, the owner of record of the shares of Common Stock.  PBK and ZBI also share voting and dispositive power over the shares of Common Stock that each beneficially owns with ZAM, the owner of record of the shares of Common Stock.
 
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
 
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 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.

Dated:  June 30, 2008
 

 
ZIFF ASSET MANAGEMENT, L.P.
By:         PBK Holdings, Inc., its general partner
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President

 
 
PBK HOLDINGS, INC.
 
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President
   

 
   
/s/ PHILIP B. KORSANT
 
Philip B. Korsant
 
 


 
ZBI EQUITIES, L.L.C.
By:         PBK Holdings, Inc., its sole member
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President

 
 
 
 
EXHIBIT A


The undersigned, Ziff Asset Management, L.P., a Delaware limited partnership, PBK Holdings, Inc., a Delaware corporation, Philip B. Korsant, and ZBI Equities, L.L.C., a Delaware limited liability company, hereby agree and acknowledge that the information required by this Schedule 13G, to which this Agreement is attached as an exhibit, is filed on behalf of each of them.  The undersigned further agree that any further amendments or supplements thereto shall also be filed on behalf of each of them.

Dated:  June 30, 2008
 
 

 
ZIFF ASSET MANAGEMENT, L.P.
By:         PBK Holdings, Inc., its general partner
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President

 
 
PBK HOLDINGS, INC.
 
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President
   

 
   
/s/ PHILIP B. KORSANT
   
Philip B. Korsant
 
 


 
ZBI EQUITIES, L.L.C.
By:         PBK Holdings, Inc., its sole member
 
 
 
By:
/s/ DAVID GRAY
 
Name:
David Gray
 
Title:
Vice President