Top 100 Contractors in PSC 6665: Hazard-Detecting Instruments and Apparatus, FY2021

Full ranking

Rank	Contractor	Net obligations	Share	Trend
1	OSI Systems Inc. 2 awardees, including Rapiscan Systems Inc. and American Science & Engineering Inc. Top agencies DHS (Department of Homeland Security) USAF (Department of the Air Force) Navy (Department of the Navy)	$211,407,187	31.5%	Rank history: #3 in FY2022, #4 in FY2023 and not on the FY2024–FY2025 lists; up 1 since FY2020.
2	Leidos Holdings, Inc. 3 awardees, including Leidos, Inc. Top agencies DHS (Department of Homeland Security)	$152,655,709	22.8%	Rank history: #8 in FY2022, #1 in FY2023, not on the FY2024 list and #2 in FY2025; up 3 since FY2020.
3	Flir Systems Inc. 2 awardees, including Teledyne Flir Unmanned Ground Systems, Inc. Top agencies Army (Department of the Army)	$73,972,819	11.0%	Rank history: #11 in FY2022, #3 in FY2023 and not on the FY2024–FY2025 lists; down 2 since FY2020.
4	Astrophysics Inc. Top agencies DHS (Department of Homeland Security) GSA (General Services Administration) DOJ (Department of Justice)	$61,034,764	9.1%	Rank history: #79 in FY2022, #17 in FY2023, #5 in FY2024 and #5 in FY2025; up 47 since FY2020.
5	Qinetiq Group PLC Through Foster-Miller, Inc. Top agencies Army (Department of the Army)	$60,904,576	9.1%	Rank history: #4 in FY2022, #42 in FY2023 and not on the FY2024–FY2025 lists; up 1 since FY2020.
6	Smiths Group PLC Through Smiths Detection Inc. Top agencies DHS (Department of Homeland Security) Army (Department of the Army) WHS (DOD Washington Headquarters Service)	$28,557,993	4.3%	Rank history: #2 in FY2022, #5 in FY2023 and not on the FY2024–FY2025 lists; down 3 since FY2020.
7	L3Harris Technologies, Inc. Top agencies USAF (Department of the Air Force)	$17,990,372	2.7%	Rank history: not on the FY2022–FY2023 lists, #21 in FY2024 and #7 in FY2025; up 164 since FY2020.
8	Viken Detection Corporation Top agencies DHS (Department of Homeland Security) Navy (Department of the Navy) USAF (Department of the Air Force)	$7,834,497	1.2%	Rank history: not on the FY2022–FY2025 lists; down 1 since FY2020.
9	Mirion Technologies (CANBERRA) Inc. 5 awardees, including Mirion Technologies (Mgpi), Inc. and Mirion Technologies (Gds), Inc. Top agencies Army (Department of the Army) Navy (Department of the Navy) DTRA (Defense Threat Reduction Agency)	$6,652,483	1.0%	Rank history: #16 in FY2022, #10 in FY2023 and not on the FY2024–FY2025 lists; down 1 since FY2020.
10	Alakai Defense Systems, Inc. Top agencies Navy (Department of the Navy)	$6,436,121	1.0%	Rank history: #27 in FY2022, #2 in FY2023, not on the FY2024 list and #21 in FY2025; new, not ranked in FY2020.
11	Spectral Labs Incorporated Top agencies Navy (Department of the Navy)	$4,374,879	0.7%	Rank history: #12 in FY2022, #11 in FY2023, not on the FY2024 list and #42 in FY2025; up 5 since FY2020.
12	Federal Resources Supply Company 3 awardees, including Wright Tool Company, LLC Top agencies DLA (Defense Logistics Agency) DHS (Department of Homeland Security) DOJ (Department of Justice)	$4,099,831	0.6%	Rank history: #7 in FY2022, #14 in FY2023, #12 in FY2024 and #28 in FY2025; down 1 since FY2020.
13	Ludlum Measurements, Inc. Top agencies Army (Department of the Army)	$3,473,111	0.5%	Rank history: #5 in FY2022, #6 in FY2023, #1 in FY2024 and #6 in FY2025; new, not ranked in FY2020.
14	Draeger Inc. 2 awardees Top agencies DLA (Defense Logistics Agency)	$2,295,482	0.3%	Rank history: #13 in FY2022, #15 in FY2023, #16 in FY2024 and #13 in FY2025; up 8 since FY2020.
15	Hopewell Designs, Inc. Top agencies Navy (Department of the Navy)	$2,129,351	0.3%	Rank history: #20 in FY2022, #18 in FY2023, #17 in FY2024 and #29 in FY2025; up 10 since FY2020.
16	MSA Safety Sales LLC 2 awardees, including Parasense, Inc. Top agencies Navy (Department of the Navy) DOL (Department of Labor) DLA (Defense Logistics Agency)	$1,610,984	0.2%	Rank history: #15 in FY2022, #12 in FY2023 and not on the FY2024–FY2025 lists; up 1 since FY2020.
17	BNC Corp. Top agencies DTRA (Defense Threat Reduction Agency) Navy (Department of the Navy)	$1,541,905	0.2%	Rank history: #72 in FY2022, #21 in FY2023, not on the FY2024 list and #23 in FY2025; down 5 since FY2020.
18	Chemring Group PLC 2 awardees, including Chemring Sensors and Electronic Systems, Inc. Top agencies Army (Department of the Army)	$1,444,290	0.2%	Rank history: #10 in FY2022, #20 in FY2023 and not on the FY2024–FY2025 lists; down 14 since FY2020.
19	Saint-Gobain Corporation (1) Through Luxium Solutions, LLC Top agencies DTRA (Defense Threat Reduction Agency)	$1,216,585	0.2%	Rank history: not on the FY2022 list, #26 in FY2023 and not on the FY2024–FY2025 lists; up 69 since FY2020.
20	Chemring Sensors and Electronic Systems, Inc. Top agencies Army (Department of the Army)	$1,054,971	0.2%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
21	Jag Components, LLC Top agencies DLA (Defense Logistics Agency)	$961,459	0.1%	Rank history: #17 in FY2022, #33 in FY2023, #55 in FY2024 and #52 in FY2025; unchanged since FY2020.
22	General Nucleonics, Inc. Top agencies Navy (Department of the Navy)	$748,298	0.1%	Rank history: #14 in FY2022, not on the FY2023 list, #45 in FY2024 and #20 in FY2025; up 132 since FY2020.
23	S I T Corporation Top agencies DLA (Defense Logistics Agency) Navy (Department of the Navy)	$725,494	0.1%	Rank history: #52 in FY2022, #82 in FY2023, #100 in FY2024 and #95 in FY2025; up 36 since FY2020.
24	General Electric Company Through Reuter-Stokes, LLC Top agencies DTRA (Defense Threat Reduction Agency)	$673,360	0.1%	Rank history: #65 in FY2022, #16 in FY2023, #49 in FY2024 and #37 in FY2025; new, not ranked in FY2020.
25	Kampi Components Co Inc. Top agencies DLA (Defense Logistics Agency) Navy (Department of the Navy)	$637,460	0.1%	Rank history: #21 in FY2022, #43 in FY2023, #54 in FY2024 and #78 in FY2025; up 3 since FY2020.
26	Quicksilver Analytics Inc. Top agencies DOS (Department of State) DLA (Defense Logistics Agency)	$631,965	0.1%	Rank history: #48 in FY2022 and not on the FY2023–FY2025 lists; up 4 since FY2020.
27	Advetage Solutions LLC Top agencies Navy (Department of the Navy)	$589,447	0.1%	Rank history: #68 in FY2022 and not on the FY2023–FY2025 lists; up 71 since FY2020.
28	AMG Services Inc. Top agencies DLA (Defense Logistics Agency)	$547,200	0.1%	Rank history: #19 in FY2022 and not on the FY2023–FY2025 lists; up 38 since FY2020.
29	Bruker Corporation Through Bruker Detection Corp Top agencies DLA (Defense Logistics Agency) Navy (Department of the Navy)	$479,932	0.1%	Rank history: #9 in FY2022, #8 in FY2023, #8 in FY2024 and #12 in FY2025; down 20 since FY2020.
30	B & H International LLC Top agencies Navy (Department of the Navy) DLA (Defense Logistics Agency) USAF (Department of the Air Force)	$472,652	0.1%	Rank history: #18 in FY2022, #99 in FY2023, #18 in FY2024 and #56 in FY2025; up 3 since FY2020.
31	Advanced Test Equipment Corporation Top agencies Navy (Department of the Navy)	$456,855	0.1%	Rank history: #55 in FY2022, #64 in FY2023 and not on the FY2024–FY2025 lists; up 3 since FY2020.
32	Astrodyne, Inc. Top agencies DLA (Defense Logistics Agency)	$422,290	0.1%	Rank history: not on the FY2022–FY2025 lists; up 14 since FY2020.
33	Luxfer Holdings PLC Through Luxfer Magtech, Inc. Top agencies Army (Department of the Army)	$389,652	0.1%	Rank history: #6 in FY2022, #13 in FY2023 and not on the FY2024–FY2025 lists; down 23 since FY2020.
34	Pioneer Industries, LLC Top agencies DLA (Defense Logistics Agency)	$385,633	0.1%	Rank history: #41 in FY2022, #79 in FY2023, not on the FY2024 list and #82 in FY2025; up 26 since FY2020.
35	Victor Forward LLC Top agencies USAF (Department of the Air Force)	$375,911	0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
36	R. S. Means Company LLC 2 awardees, including Landauer, Inc. and Fluke Electronics Corp Top agencies USAF (Department of the Air Force) VA (Department of Veterans Affairs)	$347,445	0.1%	Rank history: #38 in FY2022 and not on the FY2023–FY2025 lists; up 2 since FY2020.
37	Analytical Industries, Inc. Top agencies Navy (Department of the Navy)	$324,370	<0.1%	Rank history: #39 in FY2022, #31 in FY2023, #41 in FY2024 and #35 in FY2025; up 41 since FY2020.
38	SZY Holdings, LLC Top agencies DLA (Defense Logistics Agency)	$295,955	<0.1%	Rank history: #50 in FY2022, #27 in FY2023, #20 in FY2024 and #72 in FY2025; up 10 since FY2020.
39	V. Lopez JR. & Sons General Engineering Contractors, Inc. Top agencies DLA (Defense Logistics Agency)	$263,157	<0.1%	Rank history: not on the FY2022–FY2025 lists; down 8 since FY2020.
40	The Cemtech Delmar Partnership Inc. Top agencies EPA (Environmental Protection Agency)	$233,805	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
41	Quaesta Instruments, LLC Top agencies DTRA (Defense Threat Reduction Agency)	$210,000	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
42	Burhani Enterprises Inc. Top agencies DOJ (Department of Justice) DLA (Defense Logistics Agency)	$201,738	<0.1%	Rank history: not on the FY2022 list, #51 in FY2023, #28 in FY2024 and not on the FY2025 list; up 47 since FY2020.
43	Phoenix Systems Engineering Inc. Top agencies DLA (Defense Logistics Agency)	$199,110	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 102 since FY2020.
44	Socal Air, Inc. Top agencies DLA (Defense Logistics Agency)	$193,500	<0.1%	Rank history: #54 in FY2022, #70 in FY2023 and not on the FY2024–FY2025 lists; up 107 since FY2020.
45	Ametek Inc. 3 awardees, including Taylor Hobson Inc., Ametek Arizona Instrument LLC and Advanced Measurement Technology Inc. Top agencies Army (Department of the Army) DHS (Department of Homeland Security) Smithsonian (Smithsonian Institution)	$189,259	<0.1%	Rank history: not on the FY2022 list, #28 in FY2023, #27 in FY2024 and not on the FY2025 list; up 64 since FY2020.
46	Potomac River Group, LLC Top agencies DOS (Department of State)	$184,671	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
47	MCI Solutions Inc. Top agencies DLA (Defense Logistics Agency)	$170,010	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
48	In Speck Corp Top agencies Navy (Department of the Navy)	$160,817	<0.1%	Rank history: not on the FY2022 list, #55 in FY2023 and not on the FY2024–FY2025 lists; up 7 since FY2020.
49	Rotunda Scientific Technologies LLC Top agencies Army (Department of the Army)	$154,435	<0.1%	Rank history: #31 in FY2022, #35 in FY2023 and not on the FY2024–FY2025 lists; new, not ranked in FY2020.
50	Sigma Products & MFG Top agencies DLA (Defense Logistics Agency)	$145,648	<0.1%	Rank history: #53 in FY2022, not on the FY2023 list, #86 in FY2024 and not on the FY2025 list; new, not ranked in FY2020.
51	Thermo Electron Corporation 2 awardees, including Thermo Eberline LLC and Thermo Scientific Portable Analytical Instruments Inc. Top agencies Navy (Department of the Navy) DOJ (Department of Justice)	$139,606	<0.1%	Rank history: #26 in FY2022, #89 in FY2023 and not on the FY2024–FY2025 lists; up 46 since FY2020.
52	Par Defense Industries, LLC Top agencies DLA (Defense Logistics Agency)	$138,053	<0.1%	Rank history: #61 in FY2022, not on the FY2023 list, #88 in FY2024 and not on the FY2025 list; up 74 since FY2020.
53	Bacharach, Inc. Through Parasense, Inc. Top agencies Navy (Department of the Navy)	$136,119	<0.1%	Rank history: not on the FY2022–FY2025 lists; down 35 since FY2020.
54	Skc, Inc. Top agencies DLA (Defense Logistics Agency) Army (Department of the Army)	$131,512	<0.1%	Rank history: #37 in FY2022 and not on the FY2023–FY2025 lists; up 88 since FY2020.
55	The Churchill Companies Through TSI Incorporated Top agencies HHS (Department of Health and Human Services) USDA (Department of Agriculture) Army (Department of the Army)	$113,889	<0.1%	Rank history: not on the FY2022 list, #65 in FY2023 and not on the FY2024–FY2025 lists; down 5 since FY2020.
56	World Class Solutions Incorporated Top agencies Army (Department of the Army)	$109,294	<0.1%	Rank history: #63 in FY2022, #97 in FY2023 and not on the FY2024–FY2025 lists; down 29 since FY2020.
57	Aquila, Inc. Top agencies VA (Department of Veterans Affairs) DOJ (Department of Justice)	$105,868	<0.1%	Rank history: #49 in FY2022, #66 in FY2023, #66 in FY2024 and not on the FY2025 list; up 42 since FY2020.
58	Battelle Memorial Institute Top agencies DLA (Defense Logistics Agency)	$104,540	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
59	Teledyne Technologies Incorporated 2 awardees, including Teledyne Flir Unmanned Ground Systems, Inc. and Teledyne Flir Defense, LLC Top agencies Army (Department of the Army) Navy (Department of the Navy)	$102,338	<0.1%	Rank history: #1 in FY2022, not on the FY2023 list, #15 in FY2024 and #41 in FY2025; new, not ranked in FY2020.
60	Critical Solutions International, LLC Top agencies DLA (Defense Logistics Agency)	$101,760	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 46 since FY2020.
61	Eckert & Ziegler Strahlen- UND Medizintechnik AG 2 awardees, including Eckert & Ziegler Analytics, Inc. and Eckert & Ziegler Isotope Products, Inc. Top agencies Navy (Department of the Navy)	$101,700	<0.1%	Rank history: #78 in FY2022, #49 in FY2023 and not on the FY2024–FY2025 lists; down 20 since FY2020.
62	Sharplogixx, LLC Top agencies DOJ (Department of Justice)	$98,000	<0.1%	Rank history: #29 in FY2022, #37 in FY2023 and not on the FY2024–FY2025 lists; new, not ranked in FY2020.
63	Treadwell Corporation (Delaware) Top agencies DLA (Defense Logistics Agency)	$97,716	<0.1%	Rank history: #46 in FY2022, #44 in FY2023, #31 in FY2024 and not on the FY2025 list; up 32 since FY2020.
64	Linev Systems US Inc. Top agencies DOS (Department of State)	$96,880	<0.1%	Rank history: not on the FY2022–FY2024 lists and #39 in FY2025; new, not ranked in FY2020.
65	Blue Cord Logistic Strategies Inc. Top agencies DLA (Defense Logistics Agency)	$96,232	<0.1%	Rank history: #45 in FY2022, #53 in FY2023 and not on the FY2024–FY2025 lists; up 38 since FY2020.
66	Thermo Scientific Portable Analytical Instruments Inc. Top agencies EPA (Environmental Protection Agency) DOJ (Department of Justice)	$87,714	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 126 since FY2020.
67	Phoenix Trading Inc. Top agencies DLA (Defense Logistics Agency)	$87,468	<0.1%	Rank history: #30 in FY2022, #62 in FY2023, #30 in FY2024 and not on the FY2025 list; down 43 since FY2020.
68	Martin Military Inc. Top agencies DLA (Defense Logistics Agency)	$86,289	<0.1%	Rank history: #83 in FY2022, not on the FY2023 list, #98 in FY2024 and #40 in FY2025; up 15 since FY2020.
69	Proton S.a. Top agencies USAF (Department of the Air Force)	$85,115	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
70	Ofil USA Ltd. Top agencies Navy (Department of the Navy)	$80,050	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
71	Alpha Spectra, Inc. Top agencies DTRA (Defense Threat Reduction Agency)	$78,744	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 5 since FY2020.
72	Standbuy Distributors, Inc. Top agencies DLA (Defense Logistics Agency)	$78,073	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 13 since FY2020.
73	Danaher Corporation Through Devicor Medical Products, Inc. Top agencies VA (Department of Veterans Affairs)	$75,029	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
74	Clinigence Holdings Inc. Through Healthdatix, Inc. Top agencies DOS (Department of State)	$74,991	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
75	908 Devices Inc. Top agencies DOS (Department of State)	$74,675	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
76	Chemdaq, Inc. Top agencies VA (Department of Veterans Affairs)	$73,325	<0.1%	Rank history: #99 in FY2022, #77 in FY2023, not on the FY2024 list and #98 in FY2025; new, not ranked in FY2020.
77	Assay Technology Inc. Top agencies Navy (Department of the Navy)	$73,304	<0.1%	Rank history: #73 in FY2022, #85 in FY2023, #85 in FY2024 and #87 in FY2025; down 5 since FY2020.
78	International Television Corporation Top agencies DHA (Defense Health Agency) VA (Department of Veterans Affairs) USAF (Department of the Air Force)	$68,464	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 27 since FY2020.
79	Glis Gesellschaft FUR Luftfahrt- UND Infrastruktur-Sicherheit MBH Through Glis Gesellschaft FÜR Luftfahrt- UND Infrastruktur-Sicherheit MBH Top agencies USAF (Department of the Air Force)	$65,726	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
80	Unimex Corporation Through Paragon Defense Solutions Inc. Top agencies DLA (Defense Logistics Agency)	$63,910	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 54 since FY2020.
81	Rayco Safety Inc. Top agencies DLA (Defense Logistics Agency)	$62,492	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 115 since FY2020.
82	Bruker Detection Corp Top agencies DLA (Defense Logistics Agency)	$60,632	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
83	Apollo Safety Inc. Top agencies DLA (Defense Logistics Agency)	$60,145	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 101 since FY2020.
84	Airborne Supply Inc. Top agencies DLA (Defense Logistics Agency)	$60,070	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
85	Admartec, Inc. Top agencies Navy (Department of the Navy)	$58,600	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
86	Tarrant County Association for the Blind Top agencies DLA (Defense Logistics Agency)	$57,190	<0.1%	Rank history: #44 in FY2022, #80 in FY2023 and not on the FY2024–FY2025 lists; up 5 since FY2020.
87	Zemarc Corporation Top agencies DLA (Defense Logistics Agency)	$56,865	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 24 since FY2020.
88	Neptech, Inc. Top agencies DLA (Defense Logistics Agency)	$56,176	<0.1%	Rank history: not on the FY2022–FY2025 lists; down 7 since FY2020.
89	RLH Inc. Top agencies DOI (Department of the Interior)	$52,123	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
90	Wizard Technologies Inc. Top agencies DLA (Defense Logistics Agency)	$51,858	<0.1%	Rank history: #56 in FY2022, not on the FY2023 list, #65 in FY2024 and #63 in FY2025; new, not ranked in FY2020.
91	MDF Technologies Inc. Top agencies DLA (Defense Logistics Agency)	$50,805	<0.1%	Rank history: not on the FY2022–FY2023 lists, #68 in FY2024 and #85 in FY2025; up 109 since FY2020.
92	Alpine Supply Inc. Top agencies DLA (Defense Logistics Agency)	$50,711	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
93	AFC International Inc. Top agencies EPA (Environmental Protection Agency)	$50,196	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
94	Pacific Star Corporation Top agencies DLA (Defense Logistics Agency)	$48,316	<0.1%	Rank history: not on the FY2022–FY2025 lists; up 58 since FY2020.
95	Autoclear LLC Top agencies Navy (Department of the Navy)	$47,850	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
96	RTX Corporation Through Hamilton Sundstrand Corporation Top agencies Navy (Department of the Navy)	$44,744	<0.1%	Rank history: #23 in FY2022 and not on the FY2023–FY2025 lists; new, not ranked in FY2020.
97	Taylor Chemical Company Top agencies Navy (Department of the Navy)	$44,526	<0.1%	Rank history: #96 in FY2022, #60 in FY2023, #67 in FY2024 and #73 in FY2025; down 5 since FY2020.
98	Pfeiffer Vacuum, Inc. Top agencies USAF (Department of the Air Force) Navy (Department of the Navy)	$43,714	<0.1%	Rank history: not on the FY2022–FY2025 lists; new, not ranked in FY2020.
99	Laurus Systems Inc. Top agencies USAF (Department of the Air Force)	$41,764	<0.1%	Rank history: #47 in FY2022, #22 in FY2023, #42 in FY2024 and #45 in FY2025; down 80 since FY2020.
100	Uniphos Envirotronic Inc. Top agencies DLA (Defense Logistics Agency)	$39,245	<0.1%	Rank history: not on the FY2022 list, #74 in FY2023 and not on the FY2024–FY2025 lists; down 37 since FY2020.

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 $671 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 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