401(k) · DOL Form 5500 · 2023

Board of Trustees of Supplemental Income Trust Fund 401(k) Plan

Data updated 2026-08-25

$1.7B
Total assets Very large vs avg
30,285
Participants Very large workforce
99th
Percentile by assets National rank
$54,696
Avg per participant Low balance/head
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Official DOL plan name: Supplemental Income 401(k) Plan · Sponsored by Board of Trustees of Supplemental Income Trust Fund · California · Transportation & Warehousing

$1.7B in assets, 30,285 participants

Board of Trustees of Supplemental Income Trust Fund's Supplemental Income 401(k) Plan reported $1.7B in total assets and 30,285 participants in its 2023 DOL Form 5500 filing, ranking in the 99th 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.

  • #3,310 in Transportation & Warehousing (3,362 peers)

Coverage in California

Supplemental Income 401(k) Plan covers 30,285 participants in California, 48x the typical California plan (state average ~630 per filing). Assets: $1.7B.

#3,310
in Transportation & Warehousing (3,362 peers)
+16.5%
assets growth YoY
17×
vs typical plan assets (national mean)

Supplemental Income 401(k) Plan's outsized position by total assets

Supplemental Income 401(k) Plan vs every filed plan by assets

End-of-year total assets · plan year 2023 · DOL Form 5500

$1,656,472,999 Top 1% higher than 99% of 127,068 filed plans

This plan $0 $2,050,000,000 every filed plan with reported assets, bucketed by value

Dashed line + filled bar = this entry, among filed plans.

Source U.S. Department of Labor Form 5500 filings (EBSA) · plan year 2023

Supplemental Income 401(k) Plan's mega-plan peer group by participant headcount

Plan-year 2023 Form 5500 filings with a reported participant count, partitioned by headcount band, not by assets. Supplemental Income 401(k) Plan is a mega filing (30,285 participants), the rightmost band on the breakdown.

What changed between DOL Form 5500 filings

plan year 2022 → plan year 2023

  • Supplemental Income 401(k) Plan reported net income rose from -$249M in the plan year 2022 filing to $227M in the plan year 2023 filing.
  • Supplemental Income 401(k) Plan end-of-year assets rose from $1.4B in the plan year 2022 filing to $1.7B in the plan year 2023 filing.
  • Supplemental Income 401(k) Plan reported participants rose from 28,894 in the plan year 2022 filing to 30,285 in the plan year 2023 filing.

See the national 2022→2023 release diff →

Form 5500 schedule snapshot

Filing strip 942554388 · Board of Trustees of Supplemental Income Trust Fund PY 2023 · 401(k)

Supplemental Income 401(k) Plan · $1.7B · 30,285 · 99th

  • TYPE $1.7B
  • TYPE 30,285
  • TYPE 99th
  • TYPE 401(k)
  • TYPE near Astellas US Retirement and Savings Plan
  • TYPE ind #3310

Stamps derive from this plan's Form 5500 line items (assets, participants, type, EIN, cohort placement) - not a quality rating of the sponsor. Read with Transportation & Warehousing retirement plans → · Plans in California →

Supplemental Income 401(k) Plan in the asset neighbourhood

Supplemental Income 401(k) PlanSupplemental Income 401(k) P…$1.7BAstellas US Retirement and Savings PlanAstellas US Retirement and S…$1.7BNutrien 401(k) Retirement PlanNutrien 401(k) Retirement Pl…$1.7BZions Bancorporation, N.a. Payshelter 401(k) and Employee Stock Ownership PlanZions Bancorporation, N.a. P…$1.7BBorgwarner Inc. Retirement Savings PlanBorgwarner Inc. Retirement S…$1.7B
End-of-year total assets ($B) among Supplemental Income 401(k) Plan and nearest nationwide 401(k) peers. Source: DOL Form 5500 plan year 2023.

California filing particulars

Total Assets (Beginning of Year)$1.4B
Net Assets (End of Year)$1.7B
Net Income$227M
Employer EIN942554388
Plan Effective Date1995-01-01
Filing StatusFILING RECEIVED

Sponsor Plan History (Board of Trustees of Supplemental Income Trust Fund)

Sponsor-wide plan assets over time

All Board of Trustees of Supplemental Income Trust Fund plans reported in each filing year

Latest sponsor-wide plan assets
$1.9B 31.22148391320389% vs 2022
2024 filing year
$1.2B$1.4B$1.6B$1.8B$2B 202220232024 $1.42B $1.87B ▲ +31.7%
Year Plans Participants Total Assets
2022 1 28,894 $1.4B
2023 1 30,285 $1.7B
2024 1 32,778 $1.9B

Nearby 401(k) Plans in California

Peer 401(k) plans, same state, same plan type, ranked by total assets.

Supplemental Income 401(k) Plan vs. nearby 401(k) plans in California, assets vs. participants Scatter plot of 6 data points. 050000100000150000200000250000 -200204060 Total assets ($B) Participants Supplemental Income 401(k) Plan, Total assets ($B): 1.656472999 · Participants: 30285Supplemental Income 401(k) PlanWells Fargo & Company 401(k) Plan, Total assets ($B): 51.831350351 · Participants: 193919Wells Fargo & Company 401(k) PlanGoogle LLC 401(k) Savings Plan, Total assets ($B): 39.047152408 · Participants: 122867Google LLC 401(k) Savings PlanOracle Corporation 401(k) Savings and Investment Plan, Total assets ($B): 26.320437734 · Participants: 63105Oracle Corporation 401(k) Savings and Investment PlanIntel 401(k) Savings Plan, Total assets ($B): 22.17918189 · Participants: 59863Intel 401(k) Savings PlanApple 401(k) Plan, Total assets ($B): 19.779511539 · Participants: 106111Apple 401(k) Plan
Supplemental Income 401(k) Plan vs. nearby 401(k) plans in California, assets vs. participants
Compare Supplemental Income 401(k) Plan side-by-side with 3 peers →

Scale composition for Supplemental Income 401(k) Plan

Supplemental Income 401(k) Plan reports $1.7B in end-of-year assets across 30,285 participants (0.013% of the $12.3T held by all Form 5500 filers in the national rollup , and 0.032% of 93,925,755 covered participants) - about $54,696 per participant (40% of the national average assets-per-participant) . Net income for plan year 2023 was $227M.

This plan identity (EIN 942554388, plan #002) has 3 Form 5500 filings on file from 2022 to 2024 , with end-of-year assets moving from $1.4B to $1.9B (+31.2%) while covered participants moved from 28,894 to 32,778 . Single-year sparse filers cannot show that trail.

Plan year Participants EOY assets Filing
2022 28,894 $1.4B Open filing
2023 30,285 $1.7B This page
2024 · index core 32,778 $1.9B Open filing

The same sponsor also keeps 1 other index-core plan on PlainRetire:

Supplemental Income 401(k) Plan's out-of-state 401(k) peers by assets and headcount

Outside California, the nearest 401(k) by assets is Astellas US Retirement and Savings Plan in IL ($1.7B); by covered participants it is Savings Incentive and Profit Sharing Plan for Employees of the Hobby Lobby Group in OK (30,313 participants). Same-state nearby plans are listed separately above.

Similar participant headcount

Nearest other-state filings by covered participants (30,285 participants); asset peers above are excluded.

DOL Form 5500 plan year 2023. Asset totals can differ widely at the same headcount; neither axis is a quality rating.

Frequently Asked Questions

How did Supplemental Income 401(k) Plan assets move in 2023? ▼
Supplemental Income 401(k) Plan grew sharply - up 16.5% during 2023, from $1.4B to $1.7B. Reported net income was $227M.
How have Board of Trustees of Supplemental Income Trust Fund plan assets changed over time? ▼
Across 3 plan years on file (2022-2024), Board of Trustees of Supplemental Income Trust Fund's sponsor-wide assets grew 31.2%, from $1.4B to $1.9B.
Where does Supplemental Income 401(k) Plan rank by assets among Form 5500 filers? ▼
Supplemental Income 401(k) Plan ranks in the 99th percentile by end-of-year assets among 127,072 plans that reported assets for plan year 2023 (among the largest 1% of all filed plans).
Which 401(k) plans are similar in size to Supplemental Income 401(k) Plan? ▼
Among 401(k) plans in other states, the closest by assets is Astellas US Retirement and Savings Plan in IL ($1.7B, 3,334 participants).
Which 401(k) plans cover a similar participant headcount to Supplemental Income 401(k) Plan? ▼
Among 401(k) plans in other states, the closest by covered participants is Savings Incentive and Profit Sharing Plan for Employees of the Hobby Lobby Group in OK (30,313 participants, $487M in assets).

Source: U.S. Department of Labor, Employee Benefits Security Administration (EBSA), Form 5500 public disclosure dataset. Plan year 2023.

Source: DOL EFAST2 filing system (efast.dol.gov) - original filing retrieval by EIN 942554388.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from U.S. Department of Labor Form 5500 filings (EBSA). See our methodology for details.