Immunogen, Inc. 401(k) Plan: Login, Facts & Contact Information

Immunogen, Inc. 401(k) Plan Facts

Plan name
IMMUNOGEN, INC. 401(K) PLAN AND TRUST
Plan type
401(k) with employer contributions and profit sharing
Plan sponsor
IMMUNOGEN, INC.
Participants
541 (225 active employees)
Former employees with a balance
271
Plan assets
$81,802,294 at Dec 31, 2024
Average account balance
$165,592 across 494 accounts
Employer contributions
$1,822,952 in plan year 2024 (18% of all contributions)
Recordkeeper
Fidelity Investments Institutional
Plan year
Jan 1, 2024 – Dec 31, 2024
Plan established
Sep 1, 1990
✓ Employer contributions✓ Automatic enrollment✓ Default investment for undecided participants✓ Participants choose their own investments— Self-directed brokerage window✓ Profit sharing— Company stock (ESOP)

Source: Form 5500 for plan year 2024 (Jan 1, 2024 – Dec 31, 2024), filed Oct 14, 2025. Public filing with the U.S. Department of Labor.

Money in and out in plan year 2024

  • $10.0 million went into the plan in contributions, $1.82 million of it from the employer (18%).
  • $13.5 million was paid out to participants.
  • Investment and other income added $12.0 million.
  • Administrative expenses were $15,658, about $32 per account.

How the Immunogen, Inc. 401(k) changed, 2019–2024

Plan yearParticipantsPlan assetsEmployer contributionsBenefits paid
2019470$56.5 million$911,578$10.3 million
2020399$61.0 million$388,815$7.29 million
2021372$67.0 million$493,492$5.30 million
2022368$58.5 million$954,677$4.13 million
2023523$73.3 million$1.70 million$6.11 million
2024541$81.8 million$1.82 million$13.5 million

Immunogen, Inc. 401(k) Contact Information

Phone
781-895-0600
Mailing address
830 WINTER STREET, WALTHAM MA 02451
Plan sponsor
IMMUNOGEN, INC.
Employer identification number (EIN)
04-2726691
Plan number
001

Questions about the Immunogen, Inc. 401(k)

Does Immunogen, Inc contribute to the 401(k)?

Yes. The plan reports an employer contribution arrangement. In plan year 2024 the employer contributed $1.82 million, 18% of all contributions.

Does the Immunogen, Inc 401(k) have automatic enrollment?

Yes. The plan reports automatic enrollment of eligible employees.

How many people are in the Immunogen, Inc 401(k) plan?

541 participants at the start of plan year 2024, 225 of them active employees, and 271 former employees who still had money in the plan.

What is the average 401(k) balance at Immunogen, Inc?

About $165,592 per account: $81.8 million in plan assets across 494 accounts with a balance at the end of plan year 2024.

Who manages the Immunogen, Inc 401(k) accounts?

Fidelity NetBenefits (listed on the filing as FIDELITY INVESTMENTS INSTITUTIONAL) is the plan's recordkeeper, which is where participants log in to see their balance.

I no longer work at Immunogen, Inc. How do I access my 401(k)?

Your account stays with Fidelity NetBenefits after you leave, so you can log in with the same credentials. If your balance was small, the plan may have rolled it into an IRA in your name. If you can't find it, Beagle can locate it for you.

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