401(k) · DOL Form 5500 · 2022
Iron Mountain Incorporated 401(k) Plan
Data updated 2026-08-11
- $651M
- Total assets
- 7,917
- Participants
- 98th
- Percentile by assets
- $82,272
- Avg per participant
Official DOL plan name: The Iron Mountain Companies 401(k) Plan · Sponsored by Iron Mountain Incorporated · Massachusetts · Transportation & Warehousing
$651M in assets, 7,917 participants
Iron Mountain Incorporated's The Iron Mountain Companies 401(k) Plan reported $651M in total assets and 7,917 participants in its 2022 DOL Form 5500 filing, ranking in the 98th percentile by assets among filed plans. Figures are as reported by the plan sponsor to the Department of Labor, not audited or endorsed by PlainRetire.
- 98th percentile by assets (of 139,126 plans)
- #3,780 in Transportation & Warehousing (3,876 peers)
Coverage in Massachusetts
The Iron Mountain Companies 401(k) Plan covers 7,917 participants in Massachusetts, 12x the typical Massachusetts plan (state average ~659 per filing). Assets: $651M.
- $651M
- total plan assets (2022 EOY)
- 7,917
- covered participants
- 98th
- percentile by assets (of 139,126 plans)
- $82,272
- avg assets per participant
The plan reported a net loss of $169M for the year, a single-year figure driven by markets and benefit payments, not a measure of plan health.
Participants vs Massachusetts filers
In Massachusetts, the average filing covers about 659 participants across 4,265 plans. The Iron Mountain Companies 401(k) Plan reports 7,917 participants - 12x that state average ($651M EOY assets).
Massachusetts filing particulars
| Total Assets (Beginning of Year) | $809M |
|---|---|
| Net Assets (End of Year) | $651M |
| Net Income | -$169M |
| Employer EIN | 232588479 |
| Plan Effective Date | 1988-11-09 |
| Filing Status | FILING RECEIVED |
Sponsor Plan History (Iron Mountain Incorporated)
| Year | Plans | Participants | Total Assets |
|---|---|---|---|
| 2022 | 1 | 7,917 | $651M |
| 2023 | 1 | 8,643 | $805M |
| 2024 | 1 | 9,146 | $943M |
Nearby 401(k) Plans in Massachusetts
Peer 401(k) plans, same state, same plan type, ranked by total assets.
The Iron Mountain Companies 401(k) Plan vs. nearby 401(k) plans in Massachusetts, assets vs. participants
- Fidelity Retirement Savings Plan $23.0B · 52,036
- Liberty Mutual 401(k) Plan $8.8B · 32,843
- Massachusetts Institute of Technology Supplemental 401(k) Plan $5.8B · 13,690
- Philips North America 401(k) Plan $5.2B · 19,750
- Boston Scientific Corporation 401(k) Retirement Savings Plan $4.9B · 18,359
Scale composition for The Iron Mountain Companies 401(k) Plan
The Iron Mountain Companies 401(k) Plan reports $651M in end-of-year assets across 7,917 participants (0.005% of the $12.3T held by all Form 5500 filers in the national rollup , and 0.008% of 93,925,755 covered participants) - about $82,272 per participant (60% of the national average assets-per-participant) . Net income for plan year 2022 was -$169M.
This plan identity (EIN 232588479, plan #001) has 3 Form 5500 filings on file from 2022 to 2024 , with end-of-year assets moving from $651M to $943M (+44.8%) while covered participants moved from 7,917 to 9,146 . Single-year sparse filers cannot show that trail.
| Plan year | Participants | EOY assets | Filing |
|---|---|---|---|
| 2022 | 7,917 | $651M | This page |
| 2023 | 8,643 | $805M | Open filing |
| 2024 · index core | 9,146 | $943M | Open filing |
The same sponsor also keeps 1 other index-core plan on PlainRetire:
- The Iron Mountain Companies 401(k) Plan (401(k), $943M, 9,146 participants)
Similar-Sized 401(k) Plans Nationally
401(k) plans in other states closest to The Iron Mountain Companies 401(k) Plan by total assets, not by location.
- Adm 401(k) and Employee Stock Ownership Plan for Hourly Employees (IL) $651M · 9,395
- Acosta, Inc. 401(k) Retirement Plan (FL) $652M · 21,725
- The Cleveland-Cliffs Steel Corporation Thrift Plan (OH) $652M · 2,539
- The Reynolds and Reynolds Company 401(k) Savings Plan (OH) $652M · 4,522
Frequently Asked Questions
How did The Iron Mountain Companies 401(k) Plan assets move in 2022? ▼
How have Iron Mountain Incorporated plan assets changed over time? ▼
Where does The Iron Mountain Companies 401(k) Plan rank by assets among Form 5500 filers? ▼
Which 401(k) plans are similar in size to The Iron Mountain Companies 401(k) Plan? ▼
Next read for The Iron Mountain Companies 401(k) Plan
Filing takeaways
Ways to act on The Iron Mountain Companies 401(k) Plan's numbers.
- By total assets, The Iron Mountain Companies 401(k) Plan ranks in the top 5% of all filed plans by assets. See the largest plans
- Compare it side-by-side against 3 similar 401(k) plans in Massachusetts. Compare plans
- Iron Mountain Incorporated's sponsor-wide assets have grown 44.8% since 2022 across 3 plan years on file. More Transportation & Warehousing plans