Top 100 Contractors in NAICS 561990: All Other Support Services, FY2021

Name: Top 100 Contractors in NAICS 561990: All Other Support Services, FY2021
Creator: GovTribe

Parent companies by net contract obligations Oct 1, 2020 – Sep 30, 2021 Code page on GovTribe

The top 10 won 69% of FY2021 NAICS 561990 contract dollars

Contract obligations: $1,757,678,441 Net of deobligations, by contracts coded NAICS 561990
Contractors: 885 Parent companies with an obligation
Largest contractor: Lockheed Martin Corporation $835 million, 43.3% 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	Lockheed Martin Corporation 4 awardees, including Sikorsky Aircraft Corporation Top agencies USSOCOM (United States Special Operations Command) USAF (Department of the Air Force) Army (Department of the Army)	$834,898,150	43.3%	Rank history: #1 in FY2022, #2 in FY2023, #1 in FY2024 and #1 in FY2025; unchanged since FY2020.
2	General Dynamics Corporation 2 awardees, including General Dynamics Information Technology Inc. and General Dynamics Land Systems Inc. Top agencies Army (Department of the Army)	$141,474,148	7.3%	Rank history: #2 in FY2022, #3 in FY2023, #3 in FY2024 and #3 in FY2025; up 1 since FY2020.
3	Michael Baker International, LLC Through Sallyport Global Holdings Inc. Top agencies USAF (Department of the Air Force)	$66,896,828	3.5%	Rank history: #83 in FY2022 and not on the FY2023–FY2025 lists; down 1 since FY2020.
4	Atkins Nuclear Secured Holdings Corporation Through Isotek Systems, LLC Top agencies DOE (Department of Energy)	$54,633,150	2.8%	Rank history: #4 in FY2022, #6 in FY2023, #5 in FY2024 and #4 in FY2025; up 1 since FY2020.
5	Tanaq Support Services, LLC Top agencies HHS (Department of Health and Human Services)	$50,966,007	2.6%	Rank history: #46 in FY2022, #43 in FY2023, #84 in FY2024 and not on the FY2025 list; up 11 since FY2020.
6	Lumbee Tribe Enterprises LLC Top agencies DOS (Department of State)	$42,391,159	2.2%	Rank history: #13 in FY2022, #17 in FY2023, #50 in FY2024 and not on the FY2025 list; up 6 since FY2020.
7	CGI Technologies and Solutions Inc. Through CGI Federal Inc. Top agencies DOS (Department of State)	$40,500,000	2.1%	Rank history: #5 in FY2022, #4 in FY2023 and not on the FY2024–FY2025 lists; up 1 since FY2020.
8	Jacobs Engineering Group Inc. Through Ch2M Facility Support Services, LLC Top agencies DHS (Department of Homeland Security)	$37,893,400	2.0%	Rank history: #66 in FY2022 and not on the FY2023–FY2025 lists; up 65 since FY2020.
9	Aptim Federal Services LLC Top agencies DHS (Department of Homeland Security)	$35,775,013	1.9%	Rank history: not on the FY2022–FY2025 lists; up 16 since FY2020.
10	Booz Allen Hamilton Holding Corporation Through Booz Allen Hamilton Inc. Top agencies DOE (Department of Energy) USAF (Department of the Air Force)	$30,955,540	1.6%	Rank history: #3 in FY2022, #5 in FY2023, #10 in FY2024 and #9 in FY2025; down 1 since FY2020.
11	General Atomic Technologies Corporation Through General Atomics Aeronautical Systems, Inc. Top agencies USAF (Department of the Air Force)	$30,510,039	1.6%	Rank history: #7 in FY2022, #16 in FY2023, #28 in FY2024 and not on the FY2025 list; down 7 since FY2020.
12	Trace, Inc. Top agencies DECA (Defense Commissary Agency)	$28,431,989	1.5%	Rank history: #9 in FY2022, #9 in FY2023, #6 in FY2024 and #6 in FY2025; down 5 since FY2020.
13	Checkmate Global, LLC Top agencies DHS (Department of Homeland Security) DOI (Department of the Interior)	$23,092,972	1.2%	Rank history: not on the FY2022 list, #79 in FY2023, #12 in FY2024 and #54 in FY2025; up 162 since FY2020.
14	Pride Industries Top agencies DECA (Defense Commissary Agency)	$15,498,617	0.8%	Rank history: #15 in FY2022, #10 in FY2023, #16 in FY2024 and #13 in FY2025; up 3 since FY2020.
15	Triple Canopy Inc. 2 awardees, including Centerra Group, LLC Top agencies USAF (Department of the Air Force) Navy (Department of the Navy)	$14,881,316	0.8%	Rank history: #8 in FY2022, #18 in FY2023 and not on the FY2024–FY2025 lists; up 204 since FY2020.
16	CW Group Inc Through CW Resources, Inc. Top agencies DECA (Defense Commissary Agency)	$11,428,893	0.6%	Rank history: #11 in FY2022, #11 in FY2023 and not on the FY2024–FY2025 lists; up 2 since FY2020.
17	Job Options, Incorporated Top agencies DECA (Defense Commissary Agency)	$10,882,815	0.6%	Rank history: #17 in FY2022, #13 in FY2023, #21 in FY2024 and #18 in FY2025; up 4 since FY2020.
18	Crescent Resources, L.L.C. Top agencies DECA (Defense Commissary Agency)	$8,178,176	0.4%	Rank history: not on the FY2022–FY2025 lists; up 4 since FY2020.
19	Lamain Crescent Joint Venture LLC Top agencies DECA (Defense Commissary Agency)	$6,743,528	0.3%	Rank history: #48 in FY2022 and not on the FY2023–FY2025 lists; up 1 since FY2020.
20	Booz Allen Hamilton Inc. Top agencies DOE (Department of Energy)	$6,600,000	0.3%	Rank history: not on the FY2022–FY2025 lists; down 9 since FY2020.
21	Research Triangle Institute Top agencies USAID (US Agency for International Development)	$6,500,020	0.3%	Rank history: #16 in FY2022 and not on the FY2023–FY2025 lists; up 157 since FY2020.
22	Lamain Industries LLC Top agencies DECA (Defense Commissary Agency)	$6,396,523	0.3%	Rank history: #23 in FY2022, #12 in FY2023, #11 in FY2024 and #11 in FY2025; up 17 since FY2020.
23	Palmetto Goodwill Services Top agencies USAF (Department of the Air Force)	$6,345,959	0.3%	Rank history: #20 in FY2022, #38 in FY2023 and not on the FY2024–FY2025 lists; up 4 since FY2020.
24	Koniag, Inc. Through Pacarctic, LLC Top agencies DOJ (Department of Justice)	$6,306,000	0.3%	Rank history: #34 in FY2022, #14 in FY2023 and not on the FY2024–FY2025 lists; new, not ranked in FY2020.
25	Brevard Achievement Center, Inc. Top agencies DECA (Defense Commissary Agency)	$5,915,058	0.3%	Rank history: #31 in FY2022, #27 in FY2023, #37 in FY2024 and #24 in FY2025; up 7 since FY2020.
26	IEM International, Inc. Top agencies Army (Department of the Army)	$5,821,333	0.3%	Rank history: #21 in FY2022, #24 in FY2023 and not on the FY2024–FY2025 lists; up 4 since FY2020.
27	USA Up Star LLC Top agencies Army (Department of the Army)	$5,466,150	0.3%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
28	Communication Methods, LLC Top agencies DECA (Defense Commissary Agency)	$5,334,577	0.3%	Rank history: #14 in FY2022, #20 in FY2023, #18 in FY2024 and #14 in FY2025; up 16 since FY2020.
29	Seneca Global Services LLC Top agencies DOS (Department of State) USAF (Department of the Air Force)	$4,753,635	0.2%	Rank history: not on the FY2022–FY2025 lists; up 19 since FY2020.
30	Dak Professional Services, LLC Top agencies DECA (Defense Commissary Agency)	$4,170,613	0.2%	Rank history: #39 in FY2022, #22 in FY2023, #35 in FY2024 and #68 in FY2025; up 69 since FY2020.
31	L3Harris Technologies, Inc. 2 awardees, including L3Harris Technologies Integrated Systems L.P. Top agencies USAF (Department of the Air Force)	$3,954,357	0.2%	Rank history: #77 in FY2022, #31 in FY2023 and not on the FY2024–FY2025 lists; up 24 since FY2020.
32	R&R Commissary Services, Incorporated Top agencies DECA (Defense Commissary Agency)	$3,794,763	0.2%	Rank history: #28 in FY2022, #45 in FY2023 and not on the FY2024–FY2025 lists; up 5 since FY2020.
33	21St Century Management Services, Inc. Top agencies DHA (Defense Health Agency)	$3,736,546	0.2%	Rank history: #52 in FY2022, #40 in FY2023 and not on the FY2024–FY2025 lists; new, not ranked in FY2020.
34	L L Brooks Enterprises Inc. Top agencies DECA (Defense Commissary Agency)	$3,723,551	0.2%	Rank history: #47 in FY2022, #23 in FY2023, #25 in FY2024 and #20 in FY2025; up 19 since FY2020.
35	Great Plains Enterprises Inc. Top agencies DECA (Defense Commissary Agency)	$3,562,629	0.2%	Rank history: #78 in FY2022, #29 in FY2023, #73 in FY2024 and #55 in FY2025; up 5 since FY2020.
36	Aspire Therapy Services and Consultants, Inc. Top agencies DECA (Defense Commissary Agency)	$3,358,718	0.2%	Rank history: #62 in FY2022, #37 in FY2023, #57 in FY2024 and #47 in FY2025; up 10 since FY2020.
37	Arcus Group, LLC Top agencies DHS (Department of Homeland Security)	$3,125,726	0.2%	Rank history: #40 in FY2022, #15 in FY2023, #8 in FY2024 and #7 in FY2025; down 23 since FY2020.
38	Nationwide Supplies, L.P. Top agencies DOS (Department of State)	$2,870,762	0.1%	Rank history: not on the FY2022–FY2025 lists; up 9 since FY2020.
39	General Electric Company Top agencies Army (Department of the Army)	$2,866,814	0.1%	Rank history: #33 in FY2022, #42 in FY2023, #41 in FY2024 and #29 in FY2025; up 18 since FY2020.
40	BH Services Inc. Top agencies DECA (Defense Commissary Agency)	$2,845,050	0.1%	Rank history: not on the FY2022–FY2025 lists; up 20 since FY2020.
41	Consolidated Support Services, Inc. Top agencies DECA (Defense Commissary Agency)	$2,734,071	0.1%	Rank history: #76 in FY2022, #63 in FY2023, #88 in FY2024 and #46 in FY2025; up 13 since FY2020.
42	Galapagos Federal Systems LLC Top agencies USAF (Department of the Air Force)	$2,728,299	0.1%	Rank history: #42 in FY2022, #30 in FY2023, #22 in FY2024 and #28 in FY2025; up 52 since FY2020.
43	Cgh-Global, LLC Through Cgh-Global Emergency Management Strategies LLC Top agencies USAF (Department of the Air Force)	$2,668,323	0.1%	Rank history: #27 in FY2022, #33 in FY2023, #34 in FY2024 and not on the FY2025 list; down 14 since FY2020.
44	Goodwill Industries of Central Alabama, Inc. Top agencies DECA (Defense Commissary Agency)	$2,477,821	0.1%	Rank history: #44 in FY2022, #54 in FY2023, #44 in FY2024 and #37 in FY2025; down 6 since FY2020.
45	Goodwill Industries of South Mississippi, Inc. Through Mississippi Goodworks Inc. Top agencies DECA (Defense Commissary Agency)	$2,436,173	0.1%	Rank history: not on the FY2022–FY2025 lists; up 40 since FY2020.
46	Land Shark Shredding LLC Top agencies VA (Department of Veterans Affairs) HHS (Department of Health and Human Services)	$2,349,599	0.1%	Rank history: not on the FY2022–FY2025 lists; down 5 since FY2020.
47	Challenge Enterprises of North Florida, Inc. Top agencies DECA (Defense Commissary Agency) DOL (Department of Labor)	$2,343,835	0.1%	Rank history: not on the FY2022 list, #44 in FY2023, #49 in FY2024 and #67 in FY2025; up 4 since FY2020.
48	The Right 2 Work Corporation Top agencies DECA (Defense Commissary Agency)	$2,341,943	0.1%	Rank history: #58 in FY2022, #71 in FY2023, #48 in FY2024 and #39 in FY2025; up 17 since FY2020.
49	W. Harris, Government Services Contractor, Inc. Top agencies DECA (Defense Commissary Agency)	$2,315,713	0.1%	Rank history: #19 in FY2022, #28 in FY2023, #30 in FY2024 and #21 in FY2025; up 10 since FY2020.
50	C & S Jones Group LLC Top agencies DECA (Defense Commissary Agency)	$2,221,746	0.1%	Rank history: not on the FY2022–FY2025 lists; down 8 since FY2020.
51	Competitive Vets LLC Top agencies DOT (Department of Transportation)	$2,190,164	0.1%	Rank history: not on the FY2022–FY2025 lists; down 18 since FY2020.
52	Downtown Business Improvement District Corp Top agencies GSA (General Services Administration)	$2,150,627	0.1%	Rank history: #36 in FY2022, #53 in FY2023, #65 in FY2024 and #57 in FY2025; down 3 since FY2020.
53	Challenge Unlimited, Inc. Top agencies DECA (Defense Commissary Agency)	$2,127,879	0.1%	Rank history: #60 in FY2022, #55 in FY2023, #55 in FY2024 and #32 in FY2025; up 3 since FY2020.
54	Shares, Inc. Top agencies Commerce (Department of Commerce) Navy (Department of the Navy)	$2,111,545	0.1%	Rank history: not on the FY2022–FY2025 lists; up 278 since FY2020.
55	The Siegel Group, LLC Top agencies Army (Department of the Army) USAF (Department of the Air Force)	$2,097,076	0.1%	Rank history: #45 in FY2022 and not on the FY2023–FY2025 lists; up 42 since FY2020.
56	Servtech Top agencies DECA (Defense Commissary Agency)	$2,028,146	0.1%	Rank history: #35 in FY2022, #36 in FY2023, #24 in FY2024 and #16 in FY2025; up 93 since FY2020.
57	Bayaud Enterprises, Inc. Top agencies VA (Department of Veterans Affairs) DOI (Department of the Interior)	$1,987,369	0.1%	Rank history: #67 in FY2022, #52 in FY2023 and not on the FY2024–FY2025 lists; up 25 since FY2020.
58	Nysarc Inc. 2 awardees Top agencies Army (Department of the Army) USAF (Department of the Air Force)	$1,852,004	0.1%	Rank history: #49 in FY2022, #59 in FY2023 and not on the FY2024–FY2025 lists; up 69 since FY2020.
59	Bmmi BSC Top agencies USAID (US Agency for International Development)	$1,828,715	0.1%	Rank history: not on the FY2022–FY2025 lists; down 23 since FY2020.
60	New Leaf, Inc. Top agencies DECA (Defense Commissary Agency)	$1,794,918	0.1%	Rank history: #85 in FY2022, #90 in FY2023, not on the FY2024 list and #95 in FY2025; up 3 since FY2020.
61	Patlin Services LLC Top agencies DECA (Defense Commissary Agency)	$1,792,667	0.1%	Rank history: not on the FY2022–FY2025 lists; down 16 since FY2020.
62	Casillas Partners LLC Top agencies DECA (Defense Commissary Agency)	$1,779,928	0.1%	Rank history: #95 in FY2022 and not on the FY2023–FY2025 lists; up 29 since FY2020.
63	Logistical Customer Service, Inc. Top agencies DECA (Defense Commissary Agency)	$1,773,212	0.1%	Rank history: not on the FY2022 list, #82 in FY2023, #46 in FY2024 and #41 in FY2025; up 40 since FY2020.
64	Stericycle Inc. 9 awardees, including Shred-It USA LLC Top agencies VA (Department of Veterans Affairs) DOJ (Department of Justice) Army (Department of the Army)	$1,740,535	0.1%	Rank history: #64 in FY2022, #65 in FY2023 and not on the FY2024–FY2025 lists; up 29 since FY2020.
65	Millennium Health & Fitness, Inc. Top agencies WHS (DOD Washington Headquarters Service) DHRA (Defense Human Resources Activity)	$1,724,857	0.1%	Rank history: #57 in FY2022, #57 in FY2023, #72 in FY2024 and #60 in FY2025; up 3 since FY2020.
66	F & D Federal LLC Top agencies DOS (Department of State)	$1,689,394	0.1%	Rank history: not on the FY2022–FY2025 lists; up 53 since FY2020.
67	LEO Tech LLC Top agencies USAF (Department of the Air Force)	$1,672,681	0.1%	Rank history: #50 in FY2022 and not on the FY2023–FY2025 lists; up 10 since FY2020.
68	Assets Inc. Top agencies DECA (Defense Commissary Agency)	$1,644,978	0.1%	Rank history: #51 in FY2022, #75 in FY2023, #80 in FY2024 and #71 in FY2025; down 7 since FY2020.
69	Peninsula Services Top agencies DECA (Defense Commissary Agency)	$1,623,131	0.1%	Rank history: #55 in FY2022, #62 in FY2023 and not on the FY2024–FY2025 lists; up 1 since FY2020.
70	Good Vocations, Inc. Top agencies DECA (Defense Commissary Agency)	$1,592,976	0.1%	Rank history: #69 in FY2022, #49 in FY2023, #51 in FY2024 and #36 in FY2025; down 8 since FY2020.
71	Cfol International Inc. Top agencies VA (Department of Veterans Affairs)	$1,550,765	0.1%	Rank history: #54 in FY2022, not on the FY2023 list, #66 in FY2024 and #45 in FY2025; new, not ranked in FY2020.
72	F2 Solutions LLC Top agencies HHS (Department of Health and Human Services)	$1,501,204	0.1%	Rank history: #61 in FY2022 and not on the FY2023–FY2025 lists; up 9 since FY2020.
73	Network Enterprises Inc. Top agencies DECA (Defense Commissary Agency)	$1,437,989	0.1%	Rank history: not on the FY2022–FY2023 lists, #75 in FY2024 and #44 in FY2025; up 3 since FY2020.
74	Mavagi Enterprises, Inc. Top agencies DECA (Defense Commissary Agency)	$1,428,089	0.1%	Rank history: #38 in FY2022, not on the FY2023 list, #70 in FY2024 and not on the FY2025 list; up 67 since FY2020.
75	Dependable On-Site Scan & Shred, Inc. Top agencies VA (Department of Veterans Affairs) ED (Department of Education) DHS (Department of Homeland Security)	$1,410,887	0.1%	Rank history: #56 in FY2022, #47 in FY2023, #56 in FY2024 and #53 in FY2025; up 31 since FY2020.
76	Southwest Business Improvement District Top agencies GSA (General Services Administration)	$1,393,679	0.1%	Rank history: not on the FY2022–FY2025 lists; down 2 since FY2020.
77	Fairbanks Resource Agency, Inc. Top agencies DECA (Defense Commissary Agency)	$1,378,999	0.1%	Rank history: not on the FY2022 list, #93 in FY2023 and not on the FY2024–FY2025 lists; up 39 since FY2020.
78	Inmar Clearing Inc. Top agencies DECA (Defense Commissary Agency)	$1,329,250	0.1%	Rank history: not on the FY2022–FY2025 lists; up 1 since FY2020.
79	Nippon Telegraph and Telephone Corporation Through NTT Data Federal Services, Inc. Top agencies DOJ (Department of Justice)	$1,323,617	0.1%	Rank history: not on the FY2022–FY2025 lists; down 27 since FY2020.
80	Goodwill Easter Seals Miami Valley Top agencies DECA (Defense Commissary Agency)	$1,320,634	0.1%	Rank history: #68 in FY2022, not on the FY2023 list, #83 in FY2024 and #63 in FY2025; up 3 since FY2020.
81	Imax Service Corp Top agencies DECA (Defense Commissary Agency)	$1,305,709	0.1%	Rank history: #74 in FY2022, #61 in FY2023 and not on the FY2024–FY2025 lists; up 7 since FY2020.
82	Elyon International, Inc. Top agencies USDA (Department of Agriculture)	$1,249,376	0.1%	Rank history: #65 in FY2022, #66 in FY2023 and not on the FY2024–FY2025 lists; down 7 since FY2020.
83	Chickasaw Defense Logistics, LLC Top agencies USAF (Department of the Air Force)	$1,240,989	0.1%	Rank history: not on the FY2022–FY2025 lists; up 3 since FY2020.
84	Perkins & Associates LLC Top agencies DECA (Defense Commissary Agency)	$1,239,277	0.1%	Rank history: not on the FY2022–FY2025 lists; down 18 since FY2020.
85	Usgbf NSF LLC Top agencies NSF (National Science Foundation)	$1,200,000	0.1%	Rank history: not on the FY2022–FY2025 lists; up 32 since FY2020.
86	Om Group, Inc. Top agencies Army (Department of the Army)	$1,198,217	0.1%	Rank history: #72 in FY2022 and not on the FY2023–FY2025 lists; down 15 since FY2020.
87	Safeguard Document Destruction Inc. Top agencies SSA (Social Security Administration) VA (Department of Veterans Affairs) DHS (Department of Homeland Security)	$1,153,024	0.1%	Rank history: #91 in FY2022 and not on the FY2023–FY2025 lists; down 9 since FY2020.
88	Clean Solution Services Inc. Top agencies DECA (Defense Commissary Agency) GSA (General Services Administration)	$1,091,375	0.1%	Rank history: not on the FY2022–FY2025 lists; up 32 since FY2020.
89	City of Murfreesboro Top agencies VA (Department of Veterans Affairs)	$1,063,266	0.1%	Rank history: #73 in FY2022, #78 in FY2023 and not on the FY2024–FY2025 lists; new, not ranked in FY2020.
90	Bellator Group Inc. Top agencies DOS (Department of State)	$1,032,281	0.1%	Rank history: not on the FY2022–FY2025 lists; up 72 since FY2020.
91	Tellus LLC Top agencies DECA (Defense Commissary Agency)	$1,031,394	0.1%	Rank history: not on the FY2022–FY2025 lists; up 46 since FY2020.
92	W. & O. Supply Inc. 2 awardees, including The Hiller Companies LLC Top agencies Navy (Department of the Navy) DHS (Department of Homeland Security)	$1,014,248	0.1%	Rank history: not on the FY2022 list, #95 in FY2023 and not on the FY2024–FY2025 lists; up 78 since FY2020.
93	Advanced Project Consulting, LLC Top agencies Army (Department of the Army)	$999,475	0.1%	Rank history: #97 in FY2022 and not on the FY2023–FY2025 lists; up 3 since FY2020.
94	Coastal Enterprises of Jacksonville Inc. Top agencies DECA (Defense Commissary Agency)	$984,778	0.1%	Rank history: not on the FY2022 list, #69 in FY2023, #79 in FY2024 and #69 in FY2025; down 5 since FY2020.
95	I Tech AG LLC Top agencies Treasury (Department of the Treasury)	$980,045	0.1%	Rank history: #93 in FY2022, #100 in FY2023, #98 in FY2024 and not on the FY2025 list; new, not ranked in FY2020.
96	Western Fire & Safety Co, Inc. Top agencies Navy (Department of the Navy)	$979,226	0.1%	Rank history: #53 in FY2022 and not on the FY2023–FY2025 lists; up 46 since FY2020.
97	Alan E Fricke Memorials Inc Through Fricke, Alan E Memorials Inc. Top agencies VA (Department of Veterans Affairs)	$959,835	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
98	Goodwill Industries of Southern California Top agencies DECA (Defense Commissary Agency)	$944,627	<0.1%	Rank history: #88 in FY2022, not on the FY2023 list, #90 in FY2024 and not on the FY2025 list; up 40 since FY2020.
99	Cam Services, Inc. Top agencies DECA (Defense Commissary Agency)	$941,381	<0.1%	Rank history: #92 in FY2022 and not on the FY2023–FY2025 lists; new, not ranked in FY2020.
100	Reclamation Technologies Inc. Through Agas US Inc. Top agencies DLA (Defense Logistics Agency)	$916,269	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 130 since FY2020.

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100 of 885 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 $1.93 billion 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 2021 ran Oct 1, 2020 – Sep 30, 2021. 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 FY2020. "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 FY2020 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 561990 contractors in FY2021?

1. Lockheed Martin Corporation ($835M), 2. General Dynamics Corporation ($141M), 3. Michael Baker International, LLC ($66.9M), 4. Atkins Nuclear Secured Holdings Corporation ($54.6M), 5. Tanaq Support Services, LLC ($51M), 6. Lumbee Tribe Enterprises LLC ($42.4M), 7. CGI Technologies and Solutions Inc. ($40.5M), 8. Jacobs Engineering Group Inc. ($37.9M), 9. Aptim Federal Services LLC ($35.8M), 10. Booz Allen Hamilton Holding Corporation ($31M).

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