Top 100 Contractors in NAICS 561621: Security Systems Services (except Locksmiths), FY2024

Name: Top 100 Contractors in NAICS 561621: Security Systems Services (except Locksmiths), FY2024
Creator: GovTribe

Parent companies by net contract obligations Oct 1, 2023 – Sep 30, 2024 Code page on GovTribe

The top 10 won 50% of FY2024 NAICS 561621 contract dollars

Contract obligations: $804,540,301 Net of deobligations, by contracts coded NAICS 561621
Contractors: 980 Parent companies with an obligation
Largest contractor: M. C. Dean Inc. $102 million, 12.0% of obligations
Data as of: Oct 14, 2026

Contract actions from FPDS (SAM.gov). How the rankings work · Download all 100 rows as CSV

Full ranking

Rank	Contractor	Net obligations	Share	Trend
1	M. C. Dean Inc. Through M.c. Dean, Inc. Top agencies DOD (Department of Defense) AOUSC (Administrative Office of the U.S. Courts) DOT (Department of Transportation)	$101,758,780	12.0%	Rank history: #1 in FY2021, #1 in FY2022, #1 in FY2023 and #1 in FY2025; unchanged since FY2023.
2	Serco Inc Top agencies Navy (Department of the Navy)	$100,927,158	11.9%	Rank history: not on the FY2021–FY2022 lists, #4 in FY2023 and #2 in FY2025; up 2 since FY2023.
3	General Dynamics Corporation Through General Dynamics Mission Systems, Inc. Top agencies Navy (Department of the Navy)	$40,110,392	4.7%	Rank history: not on the FY2021–FY2023 lists and #4 in FY2025; new.
4	Advanced Technology Systems Company, Inc. (OF Virginia) Top agencies USAF (Department of the Air Force)	$39,830,516	4.7%	Rank history: #37 in FY2021, #2 in FY2022, #14 in FY2023 and not on the FY2025 list; up 10 since FY2023.
5	Securitas AB 2 awardees, including Paragon Systems Inc. and Securitas OY Top agencies DHS (Department of Homeland Security) DOS (Department of State)	$33,043,450	3.9%	Rank history: #66 in FY2021, #9 in FY2022, #2 in FY2023 and not on the FY2025 list; down 3 since FY2023.
6	Johnson Controls Security Solutions LLC 4 awardees, including Johnson Controls Inc. Top agencies AOUSC (Administrative Office of the U.S. Courts) DHS (Department of Homeland Security) HHS (Department of Health and Human Services)	$29,205,877	3.5%	Rank history: #2 in FY2021, #3 in FY2022, #3 in FY2023 and #6 in FY2025; down 3 since FY2023.
7	CACI International Inc. 3 awardees, including Caci, Inc. - Federal Top agencies USAF (Department of the Air Force)	$26,123,073	3.1%	Rank history: #5 in FY2021, #7 in FY2022, #6 in FY2023 and #5 in FY2025; down 1 since FY2023.
8	Securitas Electronic Security Inc. 2 awardees, including Paragon Systems Inc. Top agencies DHS (Department of Homeland Security)	$19,771,454	2.3%	Rank history: not on the FY2021–FY2023 lists and #3 in FY2025; new.
9	Johnson Controls Building Automation Systems, LLC Top agencies USAF (Department of the Air Force) Navy (Department of the Navy) DOJ (Department of Justice)	$17,962,596	2.1%	Rank history: #24 in FY2021, not on the FY2022–FY2023 lists and #8 in FY2025; returned.
10	Birdi Systems, Inc. Top agencies HHS (Department of Health and Human Services)	$17,226,131	2.0%	Rank history: not on the FY2021–FY2023 lists and #13 in FY2025; new.
11	Versar Security Systems, LLC Top agencies DOT (Department of Transportation) AOUSC (Administrative Office of the U.S. Courts) GAO (Government Accountability Office)	$15,987,474	1.9%	Rank history: not on the FY2021 list, #21 in FY2022, #25 in FY2023 and #20 in FY2025; up 14 since FY2023.
12	Triple Canopy Inc. Top agencies DHS (Department of Homeland Security)	$14,242,820	1.7%	Rank history: not on the FY2021–FY2023 lists and #9 in FY2025; up 156 since FY2023.
13	Scdatacom LLC Top agencies DOJ (Department of Justice) VA (Department of Veterans Affairs) USAF (Department of the Air Force)	$14,160,531	1.7%	Rank history: #72 in FY2021, #23 in FY2022, #22 in FY2023 and #11 in FY2025; up 9 since FY2023.
14	Omniplex World Services Corp Through Triple Canopy Inc. Top agencies DHS (Department of Homeland Security)	$14,088,773	1.7%	Rank history: not on the FY2021–FY2022 lists, #5 in FY2023 and not on the FY2025 list; down 9 since FY2023.
15	Chenega Integrated Security Solutions, LLC Top agencies SEC (Securities and Exchange Commission) MDA (DOD Missile Defense Agency)	$10,206,733	1.2%	Rank history: not on the FY2021–FY2023 lists and #12 in FY2025; new.
16	Cherokee Nation System Solutions LLC Top agencies Treasury (Department of the Treasury)	$8,712,578	1.0%	Rank history: #39 in FY2021, #30 in FY2022, #18 in FY2023 and not on the FY2025 list; up 2 since FY2023.
17	Media Plumbing & Heating Inc. Top agencies Navy (Department of the Navy) Army (Department of the Army) VA (Department of Veterans Affairs)	$8,175,402	1.0%	Rank history: #14 in FY2021, #14 in FY2022, #21 in FY2023 and #14 in FY2025; up 4 since FY2023.
18	Johnson Controls Inc 2 awardees, including Johnson Controls Fire Protection LP Top agencies Navy (Department of the Navy) VA (Department of Veterans Affairs) Army (Department of the Army)	$7,246,509	0.9%	Rank history: not on the FY2021–FY2023 lists and #10 in FY2025; new.
19	Parsons Corporation 3 awardees, including Xator LLC, Ptsi Managed Services Inc. and Williams Electric Co Inc. Top agencies USAF (Department of the Air Force) Smithsonian (Smithsonian Institution) Army (Department of the Army)	$7,106,865	0.8%	Rank history: not on the FY2021 list, #51 in FY2022, #31 in FY2023 and #7 in FY2025; up 12 since FY2023.
20	KBR Wyle Services LLC 2 awardees Top agencies DOT (Department of Transportation) AOUSC (Administrative Office of the U.S. Courts) DOJ (Department of Justice)	$7,070,127	0.8%	Rank history: not on the FY2021–FY2023 lists and #15 in FY2025; new.
21	Indyne, Inc. 2 awardees Top agencies USAF (Department of the Air Force)	$6,938,522	0.8%	Rank history: #15 in FY2021, #19 in FY2022, #26 in FY2023 and #18 in FY2025; up 5 since FY2023.
22	Trofholz Technologies Inc. 2 awardees Top agencies USSOCOM (United States Special Operations Command) DOI (Department of the Interior) Navy (Department of the Navy)	$5,958,761	0.7%	Rank history: #19 in FY2021, #15 in FY2022, #15 in FY2023 and #24 in FY2025; down 7 since FY2023.
23	Electronic Systems Services Inc. Top agencies Treasury (Department of the Treasury)	$5,493,893	0.6%	Rank history: not on the FY2021–FY2023 lists and #19 in FY2025; new.
24	Hurtvet Subcontracting LLC 2 awardees Top agencies VA (Department of Veterans Affairs) DOI (Department of the Interior) DOT (Department of Transportation)	$4,643,020	0.5%	Rank history: #18 in FY2021, #27 in FY2022, #16 in FY2023 and #27 in FY2025; down 8 since FY2023.
25	Srctec, LLC Top agencies USAF (Department of the Air Force) DOD (Department of Defense)	$4,614,722	0.5%	Rank history: #41 in FY2021, not on the FY2022–FY2023 lists and #22 in FY2025; returned.
26	Itm4G LLC Top agencies Army (Department of the Army) USAF (Department of the Air Force) DHS (Department of Homeland Security)	$4,200,985	0.5%	Rank history: #43 in FY2021, #22 in FY2022, #24 in FY2023 and #21 in FY2025; down 2 since FY2023.
27	V2X, Inc. Through Advantor Systems II LLC Top agencies USAF (Department of the Air Force) Army (Department of the Army) Navy (Department of the Navy)	$3,975,081	0.5%	Rank history: not on the FY2021–FY2023 lists and #41 in FY2025; new.
28	Trilogy Secured Services, L.l.c Top agencies HHS (Department of Health and Human Services) DHS (Department of Homeland Security) DECA (Defense Commissary Agency)	$3,803,910	0.4%	Rank history: #58 in FY2021, #68 in FY2022, #19 in FY2023 and #86 in FY2025; down 9 since FY2023.
29	Firelake Construction Inc 2 awardees Top agencies Army (Department of the Army) USDA (Department of Agriculture) DHS (Department of Homeland Security)	$3,610,706	0.4%	Rank history: #31 in FY2021, #41 in FY2022, #38 in FY2023 and #23 in FY2025; up 9 since FY2023.
30	Evergreen Fire Alarms LLC Top agencies Army (Department of the Army) Navy (Department of the Navy) USAF (Department of the Air Force)	$3,606,433	0.4%	Rank history: #11 in FY2021, #31 in FY2022, #20 in FY2023 and #17 in FY2025; down 10 since FY2023.
31	Xator LLC Top agencies USAF (Department of the Air Force)	$3,599,635	0.4%	Rank history: #7 in FY2021, #5 in FY2022, #8 in FY2023 and not on the FY2025 list; down 23 since FY2023.
32	Vista Defense Technologies, LLC Top agencies DHA (Defense Health Agency)	$3,507,697	0.4%	Rank history: #25 in FY2021, #36 in FY2022, #40 in FY2023 and #29 in FY2025; up 8 since FY2023.
33	Integriward LLC Top agencies DHS (Department of Homeland Security) Army (Department of the Army)	$3,412,986	0.4%	Rank history: not on the FY2021–FY2022 lists, #44 in FY2023 and not on the FY2025 list; up 11 since FY2023.
34	Integrated Security Technologies Inc. Top agencies Navy (Department of the Navy) GSA (General Services Administration) USAF (Department of the Air Force)	$3,386,708	0.4%	Rank history: #35 in FY2021, #62 in FY2022, #39 in FY2023 and #59 in FY2025; up 5 since FY2023.
35	Idemia National Security Solutions LLC Top agencies Navy (Department of the Navy)	$3,335,765	0.4%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
36	Global Resource Solutions Inc. Top agencies DHS (Department of Homeland Security) USAF (Department of the Air Force)	$3,246,157	0.4%	Rank history: #40 in FY2021, #43 in FY2022, #32 in FY2023 and #26 in FY2025; down 4 since FY2023.
37	Signet Technologies, Inc. 3 awardees, including Convergint Technologies LLC Top agencies DISA (Defense Information Systems Agency) DLA (Defense Logistics Agency) Peace Corps	$3,104,094	0.4%	Rank history: #38 in FY2021, #60 in FY2022, #30 in FY2023 and #65 in FY2025; down 7 since FY2023.
38	Total-Evergreen JV LLC Top agencies Army (Department of the Army)	$3,082,653	0.4%	Rank history: not on the FY2021 list, #45 in FY2022, #43 in FY2023 and #42 in FY2025; up 5 since FY2023.
39	Olgoonik Solutions LLC Top agencies DOE (Department of Energy)	$2,953,877	0.3%	Rank history: not on the FY2021–FY2023 lists and #16 in FY2025; new.
40	Sesanti Limited Top agencies Army (Department of the Army)	$2,901,858	0.3%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
41	Smiths Detection Inc. Top agencies DOJ (Department of Justice) DHS (Department of Homeland Security) VA (Department of Veterans Affairs)	$2,747,625	0.3%	Rank history: not on the FY2021–FY2023 lists and #38 in FY2025; new.
42	Gonzales Consulting Services Inc Top agencies SSA (Social Security Administration)	$2,704,816	0.3%	Rank history: not on the FY2021–FY2023 lists and #37 in FY2025; new.
43	Johnson Controls Industries 3 awardees, including Johnson Controls, Inc. and Johnson Controls Building Automation Systems, LLC Top agencies VA (Department of Veterans Affairs) DISA (Defense Information Systems Agency) Navy (Department of the Navy)	$2,629,931	0.3%	Rank history: not on the FY2021–FY2022 lists, #9 in FY2023 and not on the FY2025 list; down 34 since FY2023.
44	Johnson Controls Fire Protection LP 4 awardees Top agencies VA (Department of Veterans Affairs) DOT (Department of Transportation) Army (Department of the Army)	$2,609,414	0.3%	Rank history: not on the FY2021–FY2022 lists, #13 in FY2023 and not on the FY2025 list; down 31 since FY2023.
45	Siemens Aktiengesellschaft Through Siemens Industry Inc. Top agencies VA (Department of Veterans Affairs) USAF (Department of the Air Force) EPA (Environmental Protection Agency)	$2,487,070	0.3%	Rank history: #16 in FY2021, #13 in FY2022, #28 in FY2023 and not on the FY2025 list; down 17 since FY2023.
46	Systems Engineering Services Corporation Through Systems Engineering Inc. Top agencies MDA (DOD Missile Defense Agency) Army (Department of the Army) USAF (Department of the Air Force)	$2,434,454	0.3%	Rank history: not on the FY2021–FY2023 lists and #60 in FY2025; up 138 since FY2023.
47	Veterans Fire and Life Safety Corporation Top agencies VA (Department of Veterans Affairs) DHS (Department of Homeland Security) HHS (Department of Health and Human Services)	$2,402,629	0.3%	Rank history: not on the FY2021 list, #50 in FY2022, not on the FY2023 list and #28 in FY2025; up 114 since FY2023.
48	Lbyd Federal, LLC Top agencies OSD (Office of the Secretary of Defense)	$2,348,234	0.3%	Rank history: #45 in FY2021, #79 in FY2022, #45 in FY2023 and #46 in FY2025; down 3 since FY2023.
49	Echelon Services, LLC Top agencies DOD (Department of Defense) HUD (Department of Housing and Urban Development) Commerce (Department of Commerce)	$2,329,445	0.3%	Rank history: #69 in FY2021, #92 in FY2022, #54 in FY2023 and #31 in FY2025; up 5 since FY2023.
50	Warfeather, LLC Top agencies Army (Department of the Army) VA (Department of Veterans Affairs)	$2,238,941	0.3%	Rank history: not on the FY2021–FY2022 lists, #84 in FY2023 and #25 in FY2025; up 34 since FY2023.
51	HQE Systems Inc. Top agencies USAF (Department of the Air Force) Navy (Department of the Navy)	$2,177,089	0.3%	Rank history: not on the FY2021–FY2023 lists and #50 in FY2025; new.
52	Kwangmu Co.,Ltd. Top agencies Army (Department of the Army)	$2,093,222	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
53	Systems Northwest, LLC Top agencies HHS (Department of Health and Human Services)	$2,076,161	0.2%	Rank history: #56 in FY2021, #78 in FY2022, #61 in FY2023 and #44 in FY2025; up 8 since FY2023.
54	Communications Resource Inc. Top agencies Commerce (Department of Commerce) CSOSA (Court Services and Offender Supervision Agency) USDA (Department of Agriculture)	$2,064,498	0.2%	Rank history: #47 in FY2021, #46 in FY2022, not on the FY2023 list and #96 in FY2025; up 48 since FY2023.
55	Securityhunter, Inc. Top agencies Army (Department of the Army) DFAS (Defense Finance and Accounting Service) DOD (Department of Defense)	$2,060,280	0.2%	Rank history: #55 in FY2021, not on the FY2022 list, #64 in FY2023 and not on the FY2025 list; up 9 since FY2023.
56	Kastle Systems LLC Top agencies SEC (Securities and Exchange Commission) SBA (Small Business Administration) Treasury (Department of the Treasury)	$2,036,581	0.2%	Rank history: #36 in FY2021, #47 in FY2022, #52 in FY2023 and #71 in FY2025; down 4 since FY2023.
57	Red Peak Technical Services, LLC Top agencies USAF (Department of the Air Force) DHS (Department of Homeland Security)	$2,029,177	0.2%	Rank history: not on the FY2021–FY2023 lists and #40 in FY2025; new.
58	Puyenpa Services, LLC Top agencies NRC (Nuclear Regulatory Commission)	$2,018,000	0.2%	Rank history: not on the FY2021 list, #66 in FY2022, not on the FY2023 list and not on the FY2025 list; up 60 since FY2023.
59	Professionals HIR LLC 2 awardees Top agencies Navy (Department of the Navy) DLA (Defense Logistics Agency) USSOCOM (United States Special Operations Command)	$2,012,303	0.2%	Rank history: #22 in FY2021, #88 in FY2022, #100 in FY2023 and #57 in FY2025; up 41 since FY2023.
60	Concord Crossroads LLC Top agencies Army (Department of the Army) DHA (Defense Health Agency)	$2,010,138	0.2%	Rank history: #30 in FY2021, #34 in FY2022, #35 in FY2023 and not on the FY2025 list; down 25 since FY2023.
61	Shofar Communications LLC Top agencies USAF (Department of the Air Force)	$2,009,944	0.2%	Rank history: not on the FY2021–FY2022 lists, #87 in FY2023 and not on the FY2025 list; up 26 since FY2023.
62	TIC Security LLC Top agencies SEC (Securities and Exchange Commission) Commerce (Department of Commerce) DOI (Department of the Interior)	$1,953,649	0.2%	Rank history: not on the FY2021–FY2022 lists, #55 in FY2023 and not on the FY2025 list; down 7 since FY2023.
63	Sernotti Electrical Services LLC Top agencies Navy (Department of the Navy)	$1,914,815	0.2%	Rank history: not on the FY2021–FY2022 lists, #67 in FY2023 and #51 in FY2025; up 4 since FY2023.
64	Siemens Industry Inc. 2 awardees Top agencies VA (Department of Veterans Affairs) GSA (General Services Administration) DHS (Department of Homeland Security)	$1,891,888	0.2%	Rank history: not on the FY2021–FY2023 lists and #36 in FY2025; new.
65	Condortech Services, Inc. Top agencies DOI (Department of the Interior) DHS (Department of Homeland Security) RRB (Railroad Retirement Board)	$1,888,108	0.2%	Rank history: not on the FY2021–FY2022 lists, #66 in FY2023 and #80 in FY2025; up 1 since FY2023.
66	Aktarius LLC Top agencies DLA (Defense Logistics Agency) Navy (Department of the Navy)	$1,878,281	0.2%	Rank history: not on the FY2021–FY2023 lists and #48 in FY2025; new.
67	Ptsi Managed Services Inc. Top agencies Smithsonian (Smithsonian Institution)	$1,784,564	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
68	GCC Enterprises Inc. Top agencies VA (Department of Veterans Affairs)	$1,752,029	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; up 33 since FY2023.
69	Cynergy Professional Systems LLC Top agencies VA (Department of Veterans Affairs) USAF (Department of the Air Force)	$1,734,784	0.2%	Rank history: #70 in FY2021, #33 in FY2022, #57 in FY2023 and #43 in FY2025; down 12 since FY2023.
70	Applied Security Technologies Inc. Top agencies DOS (Department of State) IBWC (International Boundary and Water Commission U.S.-Mexico)	$1,713,097	0.2%	Rank history: not on the FY2021–FY2023 lists and #74 in FY2025; up 81 since FY2023.
71	American Engineering Corporation Top agencies Army (Department of the Army) USAF (Department of the Air Force)	$1,575,843	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
72	F-Concepts, Inc. Top agencies Army (Department of the Army) Navy (Department of the Navy)	$1,443,258	0.2%	Rank history: #93 in FY2021, #82 in FY2022, not on the FY2023 list and #83 in FY2025; up 37 since FY2023.
73	Ldia Holdings, LLC Top agencies USAF (Department of the Air Force)	$1,432,639	0.2%	Rank history: not on the FY2021 list, #59 in FY2022, #93 in FY2023 and #61 in FY2025; up 20 since FY2023.
74	M3T Corporation Top agencies Army (Department of the Army) Navy (Department of the Navy) VA (Department of Veterans Affairs)	$1,430,379	0.2%	Rank history: #88 in FY2021, #89 in FY2022, not on the FY2023 list and #68 in FY2025; up 56 since FY2023.
75	Clear Cloud Solutions Inc. Top agencies HHS (Department of Health and Human Services) DHRA (Defense Human Resources Activity) Navy (Department of the Navy)	$1,311,149	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; up 380 since FY2023.
76	Van Cleve & Associates, Inc. Top agencies DOJ (Department of Justice)	$1,291,273	0.2%	Rank history: not on the FY2021 list, #93 in FY2022, not on the FY2023 list and not on the FY2025 list; up 137 since FY2023.
77	Ginisis Group Inc. Top agencies USAF (Department of the Air Force)	$1,287,170	0.2%	Rank history: not on the FY2021–FY2023 lists and #45 in FY2025; new.
78	Chenega Global Protection, LLC Top agencies Treasury (Department of the Treasury)	$1,285,505	0.2%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
79	Cmn, LLC Top agencies DHS (Department of Homeland Security)	$1,246,613	0.1%	Rank history: not on the FY2021–FY2022 lists, #68 in FY2023 and #34 in FY2025; down 11 since FY2023.
80	Hana Technologies & Systems, Inc. Top agencies Navy (Department of the Navy)	$1,233,861	0.1%	Rank history: not on the FY2021 list, #73 in FY2022, #81 in FY2023 and not on the FY2025 list; up 1 since FY2023.
81	KR Contracting Inc. Top agencies OPM (Office of Personnel Management)	$1,228,924	0.1%	Rank history: #44 in FY2021, #48 in FY2022, #47 in FY2023 and #49 in FY2025; down 34 since FY2023.
82	Secsol Inc. Top agencies VA (Department of Veterans Affairs) Commerce (Department of Commerce)	$1,224,292	0.1%	Rank history: #82 in FY2021, #70 in FY2022, not on the FY2023 list and #95 in FY2025; up 21 since FY2023.
83	Security2000 LLC Top agencies Army (Department of the Army) VA (Department of Veterans Affairs) USAF (Department of the Air Force)	$1,206,128	0.1%	Rank history: #50 in FY2021, #85 in FY2022, #97 in FY2023 and #78 in FY2025; up 14 since FY2023.
84	Rock Creek Logistics, Technology, & Management Business Solutions LLC Top agencies Army (Department of the Army)	$1,199,826	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; up 88 since FY2023.
85	Advanced IT Concepts LLC Top agencies Army (Department of the Army)	$1,191,980	0.1%	Rank history: not on the FY2021–FY2022 lists, #96 in FY2023 and not on the FY2025 list; up 11 since FY2023.
86	Resolute Partners, L.L.C. Top agencies DHS (Department of Homeland Security) USAF (Department of the Air Force)	$1,189,253	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; up 66 since FY2023.
87	HEI Security LLC Top agencies VA (Department of Veterans Affairs) Navy (Department of the Navy) USAF (Department of the Air Force)	$1,180,244	0.1%	Rank history: not on the FY2021 list, #52 in FY2022, not on the FY2023 list and not on the FY2025 list; up 243 since FY2023.
88	Kbr, Inc. 2 awardees, including KBR Wyle Services, LLC Top agencies DOT (Department of Transportation) AOUSC (Administrative Office of the U.S. Courts)	$1,122,765	0.1%	Rank history: #8 in FY2021, #69 in FY2022, #11 in FY2023 and not on the FY2025 list; down 77 since FY2023.
89	J2 Associates, LLC Top agencies DLA (Defense Logistics Agency) USAF (Department of the Air Force) DOT (Department of Transportation)	$1,117,323	0.1%	Rank history: #74 in FY2021, #64 in FY2022, #99 in FY2023 and #58 in FY2025; up 10 since FY2023.
90	Swan Contracting LLC Top agencies USAF (Department of the Air Force)	$1,097,407	0.1%	Rank history: not on the FY2021–FY2022 lists, #91 in FY2023 and not on the FY2025 list; up 1 since FY2023.
91	Corelogix Consulting Inc. Top agencies DHS (Department of Homeland Security)	$1,090,045	0.1%	Rank history: #77 in FY2021, #16 in FY2022, #34 in FY2023 and #70 in FY2025; down 57 since FY2023.
92	T47 International Inc. Top agencies Army (Department of the Army)	$1,063,920	0.1%	Rank history: not on the FY2021–FY2023 lists and #87 in FY2025; new.
93	Onerain Incorporated Top agencies DOI (Department of the Interior)	$1,024,828	0.1%	Rank history: #67 in FY2021, #81 in FY2022, #92 in FY2023 and #66 in FY2025; down 1 since FY2023.
94	Johnsondanforth, Inc. Top agencies VA (Department of Veterans Affairs)	$1,015,848	0.1%	Rank history: #52 in FY2021, #74 in FY2022, #82 in FY2023 and #72 in FY2025; down 12 since FY2023.
95	Olgoonik Corporation Through Olgoonik Solutions LLC Top agencies DOE (Department of Energy)	$1,000,000	0.1%	Rank history: #26 in FY2021, #42 in FY2022, #33 in FY2023 and not on the FY2025 list; down 62 since FY2023.
96	Acoustic Technology, Inc. Top agencies USAF (Department of the Air Force)	$999,999	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
97	GJB and Associates LLC Top agencies Navy (Department of the Navy)	$998,574	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
98	Mission Support Services, LLC Top agencies DHS (Department of Homeland Security)	$969,243	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; new.
99	American VET Industries LLC Top agencies Army (Department of the Army)	$948,224	0.1%	Rank history: not on the FY2021–FY2023 lists and not on the FY2025 list; up 210 since FY2023.
100	SRC Inc. Through Srctec, LLC Top agencies USAF (Department of the Air Force)	$920,084	0.1%	Rank history: #9 in FY2021, #20 in FY2022, #17 in FY2023 and not on the FY2025 list; down 83 since FY2023.

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100 of 980 contractors listed here. See the rest on GovTribe.

How this ranking works

Source: every contract action FPDS records (as published on SAM.gov) in the period, as GovTribe received it.
Amounts are net obligations: what was obligated, less what was deobligated. Shares are of $846 million obligated before deobligations, so they never pass 100%.
Parent companies: each action counts under the ultimate parent its award record names, or under the awardee when it names none, so no dollar counts twice. Parents of the same name (Inc., LLC and the like aside) count as one company, since FPDS records a company's parent under more than one UEI over time. GovTribe corrects a few parents and names by hand; see the corrections.
Fiscal year 2024 ran Oct 1, 2023 – Sep 30, 2024. The Department of Defense reports its contract actions to FPDS about 90 days late, so a fiscal year is ranked once they're in, in February, and the list doesn't change after.
Rank changes compare with FY2023. "New" marks a company outside that period's top 500, and "Returned" one of those that was on an earlier fiscal year's list.
Rank lines show each company's rank on every fiscal year's list since FY2021, #1 at the top, on a scale that gives the top of the list more room. A dashed stretch spans years it wasn't on the list. The step from FY2023 takes the color of the rank change beside it.
Placeholder recipients FPDS uses when it names no company ("Miscellaneous Foreign Contractors" and the like) aren't ranked.

Quick answers

Who were the top 10 NAICS 561621 contractors in FY2024?

1. M. C. Dean Inc. ($102M), 2. Serco Inc ($101M), 3. General Dynamics Corporation ($40.1M), 4. Advanced Technology Systems Company, Inc. (OF Virginia) ($39.8M), 5. Securitas AB ($33M), 6. Johnson Controls Security Solutions LLC ($29.2M), 7. CACI International Inc. ($26.1M), 8. Securitas Electronic Security Inc. ($19.8M), 9. Johnson Controls Building Automation Systems, LLC ($18M), 10. Birdi Systems, Inc. ($17.2M).

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