401(k) · DOL Form 5500 · 2023

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

Data updated 2026-08-11

$1.7B
Total assets
30,285
Participants
99th
Percentile by assets
$54,696
Avg per participant
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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.

  • 99th percentile by assets (of 127,072 plans)
  • #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.

$1.7B
total plan assets (2023 EOY)
30,285
covered participants
99th
percentile by assets (of 127,072 plans)
$54,696
avg assets per participant

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 →

State
California
Industry
Transportation & Warehousing

Participants vs California filers

In California, the average filing covers about 630 participants across 15,291 plans. Supplemental Income 401(k) Plan reports 30,285 participants - 48x that state average ($1.7B EOY assets).

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)

$1.2B$1.4B$1.6B$1.8B$2B 202220232024 $1.42B $1.87B ▲ +31.7%
Total plan assets by year, all Board of Trustees of Supplemental Income Trust Fund plans on file
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

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 …Wells Fargo & Compan…Google LLC 401(k) Sa…Oracle Corporation 4…Intel 401(k) Savings…Apple 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:

Similar-Sized 401(k) Plans Nationally

401(k) plans in other states closest to Supplemental Income 401(k) Plan by total assets, not by location.

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).

Next read for Supplemental Income 401(k) Plan

Filing takeaways

Ways to act on Supplemental Income 401(k) Plan's numbers.

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.