Civic Intelligence

Mammoth Underground LLC

Plan context: Mammoth Ug 401(K) Plan

EIN 02-0646474 • Las Vegas, NV • 25 filings • 6 plans

421 W. Bonanza Rd.Las Vegas, NV 89106
Current Snapshot

Latest Year

2025

2025 Participants

77

2025 Assets

$4,538,678

2025 Contributions

$718,370

Historical Graphs

Total Assets Over Time

Aggregate end-of-year assets by filing year, excluding zero-asset years

$4,538,678$2,269,339$0200320162025YearValue
$4,538,678Latest year 2025

Participants Over Time

Largest reported end-of-year plan headcount by filing year, used to avoid double-counting participants across overlapping plans

118590200320132025YearValue
77Latest year 2025

Company Timeline

Year summaries and individual filings are combined here so you can stay in one place while moving across years and plan filings.

Year / FilingFilingsParticipantsAssetsContributionsContrib./Participant
2025177$4,538,678$718,370$9,329iApproximate average salary by contribution assumption: employee only about $233,237 at 4% or $155,491 at 6%; with 50% employer match about $155,491 at 4% or $103,661 at 6%; with 100% employer match about $116,619 at 4% or $77,746 at 6%.
Mammoth Ug 401(K) Plan-77$4,538,678$718,370$9,329iApproximate average salary by contribution assumption: employee only about $233,237 at 4% or $155,491 at 6%; with 50% employer match about $155,491 at 4% or $103,661 at 6%; with 100% employer match about $116,619 at 4% or $77,746 at 6%.
2024287$3,773,749$652,926$7,505iApproximate average salary by contribution assumption: employee only about $187,622 at 4% or $125,082 at 6%; with 50% employer match about $125,082 at 4% or $83,388 at 6%; with 100% employer match about $93,811 at 4% or $62,541 at 6%.
Mammoth Ug 401(K) Plan-73$3,773,749$652,926$8,944iApproximate average salary by contribution assumption: employee only about $223,605 at 4% or $149,070 at 6%; with 50% employer match about $149,070 at 4% or $99,380 at 6%; with 100% employer match about $111,802 at 4% or $74,535 at 6%.
Aetna/Principal-87---
2023256$2,997,866$571,260$10,201iApproximate average salary by contribution assumption: employee only about $255,027 at 4% or $170,018 at 6%; with 50% employer match about $170,018 at 4% or $113,345 at 6%; with 100% employer match about $127,513 at 4% or $85,009 at 6%.
Mammoth Ug 401(K) Plan-56$2,997,866$571,260$10,201iApproximate average salary by contribution assumption: employee only about $255,027 at 4% or $170,018 at 6%; with 50% employer match about $170,018 at 4% or $113,345 at 6%; with 100% employer match about $127,513 at 4% or $85,009 at 6%.
Aetna/Principal-0---
20221118$2,152,818$538,606$4,564iApproximate average salary by contribution assumption: employee only about $114,111 at 4% or $76,074 at 6%; with 50% employer match about $76,074 at 4% or $50,716 at 6%; with 100% employer match about $57,056 at 4% or $38,037 at 6%.
Mammoth Ug 401(K) Plan-118$2,152,818$538,606$4,564iApproximate average salary by contribution assumption: employee only about $114,111 at 4% or $76,074 at 6%; with 50% employer match about $76,074 at 4% or $50,716 at 6%; with 100% employer match about $57,056 at 4% or $38,037 at 6%.
2021147$2,169,545$452,265$9,623iApproximate average salary by contribution assumption: employee only about $240,566 at 4% or $160,378 at 6%; with 50% employer match about $160,378 at 4% or $106,918 at 6%; with 100% employer match about $120,283 at 4% or $80,189 at 6%.
Mammoth Ug 401(K) Plan-47$2,169,545$452,265$9,623iApproximate average salary by contribution assumption: employee only about $240,566 at 4% or $160,378 at 6%; with 50% employer match about $160,378 at 4% or $106,918 at 6%; with 100% employer match about $120,283 at 4% or $80,189 at 6%.
2020236$1,540,256$409,056$11,363iApproximate average salary by contribution assumption: employee only about $284,067 at 4% or $189,378 at 6%; with 50% employer match about $189,378 at 4% or $126,252 at 6%; with 100% employer match about $142,033 at 4% or $94,689 at 6%.
Mammoth Ug 401(K) Plan-36$1,540,256$409,056$11,363iApproximate average salary by contribution assumption: employee only about $284,067 at 4% or $189,378 at 6%; with 50% employer match about $189,378 at 4% or $126,252 at 6%; with 100% employer match about $142,033 at 4% or $94,689 at 6%.
HPN/PRINCIPAL-0---
2019136$1,273,602$373,700$10,381iApproximate average salary by contribution assumption: employee only about $259,514 at 4% or $173,009 at 6%; with 50% employer match about $173,009 at 4% or $115,340 at 6%; with 100% employer match about $129,757 at 4% or $86,505 at 6%.
Mammoth Ug 401(K) Plan-36$1,273,602$373,700$10,381iApproximate average salary by contribution assumption: employee only about $259,514 at 4% or $173,009 at 6%; with 50% employer match about $173,009 at 4% or $115,340 at 6%; with 100% employer match about $129,757 at 4% or $86,505 at 6%.
2018128$738,749$227,868$8,138iApproximate average salary by contribution assumption: employee only about $203,454 at 4% or $135,636 at 6%; with 50% employer match about $135,636 at 4% or $90,424 at 6%; with 100% employer match about $101,727 at 4% or $67,818 at 6%.
Mammoth Ug 401(K) Plan-28$738,749$227,868$8,138iApproximate average salary by contribution assumption: employee only about $203,454 at 4% or $135,636 at 6%; with 50% employer match about $135,636 at 4% or $90,424 at 6%; with 100% employer match about $101,727 at 4% or $67,818 at 6%.
2017128$572,185$320,911$11,461iApproximate average salary by contribution assumption: employee only about $286,528 at 4% or $191,018 at 6%; with 50% employer match about $191,018 at 4% or $127,346 at 6%; with 100% employer match about $143,264 at 4% or $95,509 at 6%.
Mammoth Ug 401(K) Plan-28$572,185$320,911$11,461iApproximate average salary by contribution assumption: employee only about $286,528 at 4% or $191,018 at 6%; with 50% employer match about $191,018 at 4% or $127,346 at 6%; with 100% employer match about $143,264 at 4% or $95,509 at 6%.
2016122$193,087$188,082$8,549iApproximate average salary by contribution assumption: employee only about $213,730 at 4% or $142,486 at 6%; with 50% employer match about $142,486 at 4% or $94,991 at 6%; with 100% employer match about $106,865 at 4% or $71,243 at 6%.
Mammoth Ug 401(K) Plan-22$193,087$188,082$8,549iApproximate average salary by contribution assumption: employee only about $213,730 at 4% or $142,486 at 6%; with 50% employer match about $142,486 at 4% or $94,991 at 6%; with 100% employer match about $106,865 at 4% or $71,243 at 6%.
2013243$1,032,449$38,898$905iApproximate average salary by contribution assumption: employee only about $22,615 at 4% or $15,077 at 6%; with 50% employer match about $15,077 at 4% or $10,051 at 6%; with 100% employer match about $11,308 at 4% or $7,538 at 6%.
Mammoth Ug 401(K) Plan-43$1,032,449$38,898$905iApproximate average salary by contribution assumption: employee only about $22,615 at 4% or $15,077 at 6%; with 50% employer match about $15,077 at 4% or $10,051 at 6%; with 100% employer match about $11,308 at 4% or $7,538 at 6%.
Mammoth Ug 401(K) Plan-0$0--
2012152$958,176$32,765$630iApproximate average salary by contribution assumption: employee only about $15,752 at 4% or $10,502 at 6%; with 50% employer match about $10,502 at 4% or $7,001 at 6%; with 100% employer match about $7,876 at 4% or $5,251 at 6%.
Mammoth Ug 401(K) Plan-52$958,176$32,765$630iApproximate average salary by contribution assumption: employee only about $15,752 at 4% or $10,502 at 6%; with 50% employer match about $10,502 at 4% or $7,001 at 6%; with 100% employer match about $7,876 at 4% or $5,251 at 6%.
2011148$926,885$34,110$711iApproximate average salary by contribution assumption: employee only about $17,766 at 4% or $11,844 at 6%; with 50% employer match about $11,844 at 4% or $7,896 at 6%; with 100% employer match about $8,883 at 4% or $5,922 at 6%.
Mammoth Ug 401(K) Plan-48$926,885$34,110$711iApproximate average salary by contribution assumption: employee only about $17,766 at 4% or $11,844 at 6%; with 50% employer match about $11,844 at 4% or $7,896 at 6%; with 100% employer match about $8,883 at 4% or $5,922 at 6%.
2010150$926,344$32,968$659iApproximate average salary by contribution assumption: employee only about $16,484 at 4% or $10,989 at 6%; with 50% employer match about $10,989 at 4% or $7,326 at 6%; with 100% employer match about $8,242 at 4% or $5,495 at 6%.
Mammoth Ug 401(K) Plan-50$926,344$32,968$659iApproximate average salary by contribution assumption: employee only about $16,484 at 4% or $10,989 at 6%; with 50% employer match about $10,989 at 4% or $7,326 at 6%; with 100% employer match about $8,242 at 4% or $5,495 at 6%.
2009155$1,132,204$51,769$941iApproximate average salary by contribution assumption: employee only about $23,531 at 4% or $15,688 at 6%; with 50% employer match about $15,688 at 4% or $10,458 at 6%; with 100% employer match about $11,766 at 4% or $7,844 at 6%.
Mammoth Ug 401(K) Plan-55$1,132,204$51,769$941iApproximate average salary by contribution assumption: employee only about $23,531 at 4% or $15,688 at 6%; with 50% employer match about $15,688 at 4% or $10,458 at 6%; with 100% employer match about $11,766 at 4% or $7,844 at 6%.
2008139$1,134,524$112,055$2,873iApproximate average salary by contribution assumption: employee only about $71,830 at 4% or $47,887 at 6%; with 50% employer match about $47,887 at 4% or $31,925 at 6%; with 100% employer match about $35,915 at 4% or $23,943 at 6%.
Mammoth Ug 401(K) Plan-39$1,134,524$112,055$2,873iApproximate average salary by contribution assumption: employee only about $71,830 at 4% or $47,887 at 6%; with 50% employer match about $47,887 at 4% or $31,925 at 6%; with 100% employer match about $35,915 at 4% or $23,943 at 6%.
2007157$0$0-
Mammoth Ug 401(K) Plan-57---
2006189$1,356,038$231,642$2,603iApproximate average salary by contribution assumption: employee only about $65,068 at 4% or $43,379 at 6%; with 50% employer match about $43,379 at 4% or $28,919 at 6%; with 100% employer match about $32,534 at 4% or $21,689 at 6%.
Mammoth Ug 401(K) Plan-89$1,356,038$231,642$2,603iApproximate average salary by contribution assumption: employee only about $65,068 at 4% or $43,379 at 6%; with 50% employer match about $43,379 at 4% or $28,919 at 6%; with 100% employer match about $32,534 at 4% or $21,689 at 6%.
2005170$1,094,075$111,509$1,593iApproximate average salary by contribution assumption: employee only about $39,825 at 4% or $26,550 at 6%; with 50% employer match about $26,550 at 4% or $17,700 at 6%; with 100% employer match about $19,912 at 4% or $13,275 at 6%.
Mammoth Ug 401(K) Plan-70$1,094,075$111,509$1,593iApproximate average salary by contribution assumption: employee only about $39,825 at 4% or $26,550 at 6%; with 50% employer match about $26,550 at 4% or $17,700 at 6%; with 100% employer match about $19,912 at 4% or $13,275 at 6%.
2004153$973,707$176,223$3,325iApproximate average salary by contribution assumption: employee only about $83,124 at 4% or $55,416 at 6%; with 50% employer match about $55,416 at 4% or $36,944 at 6%; with 100% employer match about $41,562 at 4% or $27,708 at 6%.
Mammoth Ug 401(K) Plan-53$973,707$176,223$3,325iApproximate average salary by contribution assumption: employee only about $83,124 at 4% or $55,416 at 6%; with 50% employer match about $55,416 at 4% or $36,944 at 6%; with 100% employer match about $41,562 at 4% or $27,708 at 6%.
2003147$1,168,440$76,713$1,632iApproximate average salary by contribution assumption: employee only about $40,805 at 4% or $27,203 at 6%; with 50% employer match about $27,203 at 4% or $18,135 at 6%; with 100% employer match about $20,402 at 4% or $13,602 at 6%.
Mammoth Ug 401(K) Plan-47$1,168,440$76,713$1,632iApproximate average salary by contribution assumption: employee only about $40,805 at 4% or $27,203 at 6%; with 50% employer match about $27,203 at 4% or $18,135 at 6%; with 100% employer match about $20,402 at 4% or $13,602 at 6%.