Iron Mountain 401(k) and retirement plans

Iron Mountain Incorporated, Royersford, PA. EIN 23-2588479. Annual reports 2009–2025.

Iron Mountain Incorporated has 2 active retirement plans on file. The largest is the The Iron Mountain Companies 401(k) Plan, with 13,975 participants and $1.1 billion in assets in 2025. Fidelity has been its recordkeeper since 2023. No traditional pension plan appears in Iron Mountain's filings since 2009.

Active plans: 2
Participants: 14,023
Plan assets: $1.1 billion
401(k) recordkeeper: Fidelity
Plans on file: 2
Industry: Transportation and warehousing

All 2 plans

Active plans first

The Iron Mountain Companies 401(k) Plan

401(k)Active

Active. The plan filed its annual report for the 2025 plan year.

Plan number: 001Employer EIN 23-2588479
Participants (2025): 13,975
Net assets (2025): $1.1 billion
Recordkeeper: FidelityEarlier: John Hancock (2015–2022), New York Life Investment Management (2011–2014)
Plan administrator: Iron Mountain Incorporated
1101 Enterprise Drive
Royersford, PA 19468
(855) 462-7547As filed for 2025
In effect since: November 9, 1988

Earlier plan names: The Iron Mountain Companies Puerto Rico 401(k) Plan.

Year by year, 2009 to 2025

Plan year	Participants	Net assets	Recordkeeper
2025	13,975	$1.1 billion	Fidelity
2024	13,269	$943 million	Fidelity
2023	12,353	$805 million	Fidelity
2022	11,808	$651 million	John Hancock
2021	12,473	$809 million	John Hancock
2020	12,114	$713 million	John Hancock
2019	12,288	$653 million	John Hancock
2018	12,692	$529 million	John Hancock
2017	11,815	$544 million	John Hancock
2016	12,194	$469 million	John Hancock
2015	10,792	$376 million	John Hancock
2014	10,676	$372 million	New York Life Investment Management
2013	11,219	$352 million	New York Life Investment Management
2012	11,033	$286 million	New York Life Investment Management
2011	11,316	$251 million	New York Life Investment Management
2010	45	$444,656	not listed
2009	51	$351,874	not listed

The Iron Mountain Companies Puerto Rico 401(k) Plan

Profit-sharing planActiveUnion (multiemployer)

Active. The plan filed its annual report for the 2025 plan year.

Plan number: 005Employer EIN 23-2588479
Participants (2025): 48
Net assets (2025): $2.6 million
Plan administrator: Iron Mountain Incorporated
1101 Enterprise Drive
Royersford, PA 19468
(855) 462-7547As filed for 2025
In effect since: January 8, 2006

Year by year, 2011 to 2025

Plan year	Participants	Net assets	Recordkeeper
2025	48	$2.6 million	not listed
2024	45	$2.2 million	not listed
2023	48	$1.8 million	not listed
2022	50	$1.4 million	not listed
2021	54	$1.7 million	not listed
2020	52	$1.6 million	not listed
2019	58	$1.5 million	not listed
2018	51	$1.2 million	not listed
2017	52	$1.5 million	not listed
2016	48	$1.3 million	not listed
2015	49	$1.1 million	not listed
2014	48	$1.0 million	not listed
2013	48	$882,206	not listed
2012	49	$640,183	not listed
2011	46	$518,591	not listed

If you had money in one of these plans

Call Fidelity (fidelity.com), which runs the The Iron Mountain Companies 401(k) Plan. With your Social Security number and the plan name, it can tell you whether you still have a balance and, if not, where it went.
Or call the plan administrator listed on the plan below ((855) 462-7547). That number was filed for 2025; ask for the benefits or retirement plan office.
Still stuck? The Department of Labor's benefits advisers help for free: askebsa.dol.gov or 1-866-444-3272. Never pay anyone to find your own money.

What these numbers are

They come from the Form 5500 annual reports each plan files with the Department of Labor, as the plan filed them. A plan year is usually a calendar year.
Participants counts everyone in the plan at year end: current employees, former employees who still have a balance or a pension coming, and retirees or beneficiaries being paid.
The recordkeeper is the service provider whose Schedule C entry says it keeps the plan's records. Small plans do not file Schedule C, so some plans show none.
We cannot see anyone's account. Only the plan or its recordkeeper can tell you your balance.

Sources: U.S. Department of Labor, Form 5500 datasets and PBGC trusteed plans. How we read them.

All 2 plans

The Iron Mountain Companies 401(k) Plan

The Iron Mountain Companies Puerto Rico 401(k) Plan

If you had money in one of these plans

What these numbers are

Other transportation and warehousing employers in PA