| SECURITIES AND EXCHANGE COMMISSION | |
| Washington, D.C. 20549 | |
|
| |
| SCHEDULE 13G/A | |
|
| |
| Under the Securities Exchange Act of 1934 | |
| (Amendment No. 1)* | |
|
ImmunoGen, Inc. | |
| (Name of Issuer) | |
|
Common Stock, par value $0.01 per share | |
| (Title of Class of Securities) | |
|
45253H101 | |
| (CUSIP Number) | |
|
December 31, 2017 | |
| (Date of event which requires filing of this statement) | |
| Check the appropriate box to designate the rule pursuant to which this Schedule 13G is filed: | |
| ¨ | Rule 13d-1(b) |
| x | Rule 13d-1(c) |
| ¨ | Rule 13d-1(d) |
| (Page 1 of 5 Pages) | |
______________________________
*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 the 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. 45253H1017 | 13G/A | Page 2 of 5 Pages |
| 1 |
NAMES OF REPORTING PERSONS Highbridge Capital Management, LLC | |||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP |
(a) ¨ (b) ¨ | ||
| 3 | SEC USE ONLY | |||
| 4 |
CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware | |||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH |
5 |
SOLE VOTING POWER 0 | ||
| 6 |
SHARED VOTING POWER 130,363 shares of Common Stock (including 20,500 shares of Common Stock issuable upon exercise of call options) | |||
| 7 |
SOLE DISPOSITIVE POWER 0 | |||
| 8 |
SHARED DISPOSITIVE POWER 130,363 shares of Common Stock (including 20,500 shares of Common Stock issuable upon exercise of call options)
| |||
| 9 |
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 130,363 shares of Common Stock (including 20,500 shares of Common Stock issuable upon exercise of call options) | |||
| 10 | CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | ¨ | ||
| 11 |
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.10% | |||
| 12 |
TYPE OF REPORTING PERSON IA, OO | |||
| CUSIP No. 45253H1017 | 13G/A | Page 3 of 5 Pages |
This Amendment No. 1 (this "Amendment No. 1") amends the statement on Schedule 13G filed with the Securities and Exchange Commission (the "SEC") on April 24, 2017 (the "Original Schedule 13G"), with respect to the shares of Common Stock, par value $0.01 per share (the "Common Stock"), of ImmunoGen, Inc., a Massachusetts corporation (the "Company"). Capitalized terms used herein and not otherwise defined have the meanings set forth in the Original Schedule 13G. This Amendment No. 1 amends and restates Items 4 and 5 in their entirety as set forth below.
| Item 4. | OWNERSHIP. |
|
(a) Amount beneficially owned:
As of December 31, 2017, Highbridge Capital Management, LLC, as the trading manager of 1992 MSF International Ltd. (formerly known as Highbridge International LLC) and STAR L.P. (collectively, the "Highbridge Funds"), may be deemed to be the beneficial owner of the 130,363 shares of Common Stock (including 20,500 shares of Common Stock issuable upon exercise of call options) held by the Highbridge Funds.
(b) Percent of class:
The percentages used herein and in the rest of this Schedule 13G/A are calculated based upon 132,250,680 shares of Common Stock issued and outstanding as of October 31, 2017, as reported in the Company's Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2017, filed with the Securities and Exchange Commission on November 9, 2017. Therefore, as of December 31, 2017, based on the Company's outstanding shares of Common Stock, Highbridge Capital Management, LLC may be deemed to beneficially own approximately 0.10% of the outstanding shares of Common Stock of the Company.
The foregoing should not be construed in and of itself as an admission by the Reporting Person as to beneficial ownership of the shares of Common Stock (including the shares of Common Stock issuable upon exercise of call options) held by the Highbridge Funds.
(c) Number of shares as to which such person has:
(i) Sole power to vote or to direct the vote
0
(ii) Shared power to vote or to direct the vote
See Item 4(a)
(iii) Sole power to dispose or to direct the disposition of
0
(iv) Shared power to dispose or to direct the disposition of
See Item 4(a) |
| CUSIP No. 45253H1017 | 13G/A | Page 4 of 5 Pages |
| Item 5. | OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS. |
| If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following: ý |
| CUSIP No. 45253H1017 | 13G/A | Page 5 of 5 Pages |
SIGNATURES
After reasonable inquiry and to the best of our knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.
DATED: February 14, 2018
| HIGHBRIDGE CAPITAL MANAGEMENT, LLC | ||
| By: | /s/ John Oliva | |
| Name: | John Oliva | |
| Title: | Managing Director | |