Top 100 Contractors in PSC B5: Special Studies – Not R&D, FY2025

Name: Top 100 Contractors in PSC B5: Special Studies – Not R&D, FY2025
Creator: GovTribe

Parent companies by net contract obligations Oct 1, 2024 – Sep 30, 2025 Code page on GovTribe

The top 10 won 45% of FY2025 PSC B5 contract dollars

Contract obligations: $2,998,047,228 Net of deobligations, by contracts coded PSC B5 or a code under it
Contractors: 1,745 Parent companies with an obligation
Largest contractor: Ameresco Inc. $401 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	Ameresco Inc. Top agencies GSA (General Services Administration) USAF (Department of the Air Force) DOI (Department of the Interior)	$401,380,650	12.0%	Rank history: #12 in FY2021, #20 in FY2022, #10 in FY2023 and #21 in FY2024; up 20 since FY2024.
2	Parsons Corporation 2 awardees, including Parsons Government Services Inc. Top agencies USAF (Department of the Air Force) Navy (Department of the Navy)	$197,800,081	5.9%	Rank history: not on the FY2021–FY2022 lists, #8 in FY2023 and #4 in FY2024; up 2 since FY2024.
3	CEG Solutions LLC Top agencies GSA (General Services Administration)	$157,202,388	4.7%	Rank history: not on the FY2021–FY2024 lists; new.
4	Johns Hopkins University 2 awardees, including The Johns Hopkins University Applied Physics Laboratory LLC Top agencies OSD (Office of the Secretary of Defense) USAF (Department of the Air Force) DTRA (Defense Threat Reduction Agency)	$150,680,780	4.5%	Rank history: not on the FY2021–FY2024 lists; new.
5	The Rand Corporation Top agencies OSD (Office of the Secretary of Defense) USAF (Department of the Air Force) Army (Department of the Army)	$143,942,432	4.3%	Rank history: #1 in FY2021, #1 in FY2022, #1 in FY2023 and #2 in FY2024; down 3 since FY2024.
6	Constellation Newenergy Inc. Top agencies GSA (General Services Administration)	$119,844,080	3.6%	Rank history: not on the FY2021–FY2024 lists; new.
7	The CNA Corporation Top agencies Navy (Department of the Navy) WHS (DOD Washington Headquarters Service) OSD (Office of the Secretary of Defense)	$104,835,822	3.1%	Rank history: #5 in FY2021, #6 in FY2022, #6 in FY2023 and #7 in FY2024; unchanged since FY2024.
8	Booz Allen Hamilton Holding Corporation Through Booz Allen Hamilton Inc. Top agencies NASA (National Aeronautics and Space Administration) Navy (Department of the Navy) Treasury (Department of the Treasury)	$78,185,021	2.3%	Rank history: #4 in FY2021, #3 in FY2022, #4 in FY2023 and #6 in FY2024; down 2 since FY2024.
9	Research Triangle Institute Top agencies HHS (Department of Health and Human Services) ED (Department of Education) NSF (National Science Foundation)	$75,182,711	2.2%	Rank history: #6 in FY2021, #4 in FY2022, #5 in FY2023 and #5 in FY2024; down 4 since FY2024.
10	Educational Testing Service Top agencies ED (Department of Education)	$62,824,667	1.9%	Rank history: #7 in FY2021, #7 in FY2022, #7 in FY2023 and #9 in FY2024; down 1 since FY2024.
11	Amentum Holdings, Inc. Through Amentum Services, Inc. Top agencies Army (Department of the Army)	$62,524,191	1.9%	Rank history: not on the FY2021–FY2024 lists; up 245 since FY2024.
12	Deloitte 3 awardees, including Deloitte Consulting LLP and Deloitte & Touche LLP Top agencies Treasury (Department of the Treasury) HHS (Department of Health and Human Services) DHS (Department of Homeland Security)	$50,527,151	1.5%	Rank history: not on the FY2021–FY2023 lists and #8 in FY2024; down 4 since FY2024.
13	Guidehouse Inc. 5 awardees, including Aptim Federal Services, LLC Top agencies VA (Department of Veterans Affairs) DHS (Department of Homeland Security) Treasury (Department of the Treasury)	$39,885,895	1.2%	Rank history: not on the FY2021–FY2023 lists and #27 in FY2024; up 14 since FY2024.
14	Unwin Co Top agencies DOE (Department of Energy)	$31,045,984	0.9%	Rank history: #14 in FY2021, #11 in FY2022, #11 in FY2023 and #12 in FY2024; down 2 since FY2024.
15	Johnson Controls Government Systems, LLC Top agencies GSA (General Services Administration) USAF (Department of the Air Force) DHS (Department of Homeland Security)	$27,221,699	0.8%	Rank history: not on the FY2021–FY2024 lists; up 219 since FY2024.
16	Merrick & Company Top agencies USDA (Department of Agriculture) DHS (Department of Homeland Security)	$26,796,592	0.8%	Rank history: not on the FY2021–FY2024 lists; up 94 since FY2024.
17	Westat, Inc. 2 awardees Top agencies ED (Department of Education) DOT (Department of Transportation) NSF (National Science Foundation)	$26,444,980	0.8%	Rank history: #15 in FY2021, #22 in FY2022, #16 in FY2023 and #11 in FY2024; down 6 since FY2024.
18	Honeywell International Inc. 3 awardees Top agencies GSA (General Services Administration) USAF (Department of the Air Force) DOS (Department of State)	$23,927,084	0.7%	Rank history: #53 in FY2021, #60 in FY2022, #54 in FY2023 and not on the FY2024 list; up 151 since FY2024.
19	Harvard Pilgrim Health Care, Inc. Top agencies HHS (Department of Health and Human Services)	$22,721,081	0.7%	Rank history: #11 in FY2021, #13 in FY2022, #12 in FY2023 and #13 in FY2024; down 6 since FY2024.
20	Tetra Tech, Inc. 5 awardees Top agencies EPA (Environmental Protection Agency) DOE (Department of Energy)	$22,250,353	0.7%	Rank history: #42 in FY2021, #30 in FY2022, #27 in FY2023 and #32 in FY2024; up 12 since FY2024.
21	Empower AI, Inc. Top agencies HHS (Department of Health and Human Services)	$21,812,133	0.7%	Rank history: not on the FY2021–FY2023 lists and #24 in FY2024; up 3 since FY2024.
22	RMC 2021 LLC Top agencies Navy (Department of the Navy) OSD (Office of the Secretary of Defense)	$19,866,332	0.6%	Rank history: #39 in FY2021, #15 in FY2022, #20 in FY2023 and #29 in FY2024; up 7 since FY2024.
23	Asco Power Services Inc Through Schneider Electric Buildings Americas, Inc. Top agencies USAF (Department of the Air Force) GSA (General Services Administration)	$19,662,561	0.6%	Rank history: not on the FY2021–FY2023 lists and #98 in FY2024; up 75 since FY2024.
24	Everfox LLC Top agencies USAF (Department of the Air Force)	$18,845,486	0.6%	Rank history: not on the FY2021–FY2024 lists; new.
25	Iqvia Government Solutions Inc Top agencies HHS (Department of Health and Human Services)	$18,298,122	0.5%	Rank history: not on the FY2021–FY2023 lists and #22 in FY2024; down 3 since FY2024.
26	ManTech International Corporation Through Mantech Advanced Systems International, Inc. Top agencies USAF (Department of the Air Force) DHA (Defense Health Agency)	$17,490,111	0.5%	Rank history: not on the FY2021–FY2024 lists; new.
27	Lovelace Biomedical Research Institute Top agencies HHS (Department of Health and Human Services)	$16,821,304	0.5%	Rank history: not on the FY2021–FY2022 lists, #91 in FY2023 and not on the FY2024 list; returned.
28	Gulf South Research Corp Top agencies DHS (Department of Homeland Security) Army (Department of the Army) DOT (Department of Transportation)	$16,031,967	0.5%	Rank history: not on the FY2021–FY2024 lists; new.
29	American Institute In Taiwan Top agencies DOS (Department of State)	$15,332,827	0.5%	Rank history: not on the FY2021–FY2024 lists; up 141 since FY2024.
30	Rpi-Css, LLC Top agencies Commerce (Department of Commerce)	$15,122,613	0.5%	Rank history: not on the FY2021–FY2024 lists; new.
31	Lockheed Martin Corporation 4 awardees Top agencies USAF (Department of the Air Force)	$14,601,713	0.4%	Rank history: #26 in FY2021, #14 in FY2022, #31 in FY2023 and #20 in FY2024; down 11 since FY2024.
32	Fors Marsh Group LLC Top agencies DHRA (Defense Human Resources Activity) HHS (Department of Health and Human Services)	$14,310,602	0.4%	Rank history: not on the FY2021–FY2023 lists and #37 in FY2024; up 5 since FY2024.
33	ASR Analytics, LLC Top agencies Treasury (Department of the Treasury)	$13,880,193	0.4%	Rank history: #35 in FY2021, #41 in FY2022, #39 in FY2023 and #28 in FY2024; down 5 since FY2024.
34	Emory University Top agencies HHS (Department of Health and Human Services)	$13,678,856	0.4%	Rank history: not on the FY2021 list, #46 in FY2022, #9 in FY2023 and #58 in FY2024; up 24 since FY2024.
35	Technomics Inc. Top agencies DOE (Department of Energy)	$13,497,547	0.4%	Rank history: not on the FY2021–FY2023 lists and #49 in FY2024; up 14 since FY2024.
36	Janus Research Group, LLC Top agencies Army (Department of the Army)	$13,244,728	0.4%	Rank history: #24 in FY2021, #19 in FY2022, #26 in FY2023 and #36 in FY2024; unchanged since FY2024.
37	Hdr, Inc. 3 awardees, including HDR Environmental, Operations and Construction, Inc. and HDR Engineering, Inc. Top agencies Navy (Department of the Navy)	$12,344,188	0.4%	Rank history: not on the FY2021–FY2023 lists and #39 in FY2024; up 2 since FY2024.
38	Olgoonik Solutions LLC Top agencies DOS (Department of State)	$12,063,774	0.4%	Rank history: not on the FY2021–FY2023 lists and #99 in FY2024; up 61 since FY2024.
39	Tecolote Research, Inc. Top agencies OSD (Office of the Secretary of Defense) Army (Department of the Army)	$11,168,073	0.3%	Rank history: not on the FY2021–FY2022 lists, #62 in FY2023 and #75 in FY2024; up 36 since FY2024.
40	The Mitre Corporation Top agencies DHS (Department of Homeland Security) DOS (Department of State) HHS (Department of Health and Human Services)	$10,488,789	0.3%	Rank history: not on the FY2021–FY2023 lists and #15 in FY2024; down 25 since FY2024.
41	Noresco, LLC Top agencies EPA (Environmental Protection Agency) DHS (Department of Homeland Security) DOE (Department of Energy)	$10,302,606	0.3%	Rank history: not on the FY2021–FY2022 lists, #48 in FY2023 and not on the FY2024 list; up 107 since FY2024.
42	Mccrone Associates Inc. Top agencies USAF (Department of the Air Force)	$9,961,928	0.3%	Rank history: not on the FY2021–FY2024 lists; new.
43	New South Associates, Inc. Top agencies Army (Department of the Army) DOI (Department of the Interior) VA (Department of Veterans Affairs)	$9,574,410	0.3%	Rank history: #51 in FY2021, #59 in FY2022, #70 in FY2023 and #60 in FY2024; up 17 since FY2024.
44	General Dynamics Corporation 4 awardees, including General Dynamics Information Technology, Inc. and General Dynamics-Ots, Inc. Top agencies HHS (Department of Health and Human Services) EPA (Environmental Protection Agency) USAF (Department of the Air Force)	$9,538,616	0.3%	Rank history: #74 in FY2021, #40 in FY2022, #22 in FY2023 and #33 in FY2024; down 11 since FY2024.
45	Mipps, LLC Top agencies DHA (Defense Health Agency)	$9,300,407	0.3%	Rank history: not on the FY2021–FY2022 lists, #64 in FY2023 and #55 in FY2024; up 10 since FY2024.
46	Eastern Research Group Inc. Top agencies EPA (Environmental Protection Agency) DOI (Department of the Interior) HHS (Department of Health and Human Services)	$9,242,719	0.3%	Rank history: #46 in FY2021, #52 in FY2022, #83 in FY2023 and #51 in FY2024; up 5 since FY2024.
47	National Opinion Research Center Top agencies DHRA (Defense Human Resources Activity) NSF (National Science Foundation) HHS (Department of Health and Human Services)	$9,172,900	0.3%	Rank history: not on the FY2021 list, #50 in FY2022, #40 in FY2023 and #38 in FY2024; down 9 since FY2024.
48	Muscogee Staffing Solutions, LLC Top agencies USAF (Department of the Air Force)	$9,015,000	0.3%	Rank history: not on the FY2021–FY2024 lists; new.
49	Vernadero Group Inc. Top agencies DHS (Department of Homeland Security) Army (Department of the Army) DOI (Department of the Interior)	$8,927,080	0.3%	Rank history: not on the FY2021–FY2024 lists; up 236 since FY2024.
50	Semanticbits LLC 2 awardees, including ICF Incorporated, L.L.C. and Incentive Technology Group LLC Top agencies DOT (Department of Transportation) EPA (Environmental Protection Agency) HHS (Department of Health and Human Services)	$8,615,880	0.3%	Rank history: not on the FY2021–FY2023 lists and #40 in FY2024; down 10 since FY2024.
51	University of California, Davis Top agencies EPA (Environmental Protection Agency) DOI (Department of the Interior)	$8,069,765	0.2%	Rank history: not on the FY2021–FY2024 lists; up 104 since FY2024.
52	Kpmg LLP Top agencies DOL (Department of Labor) DOT (Department of Transportation) USAF (Department of the Air Force)	$7,706,199	0.2%	Rank history: not on the FY2021–FY2023 lists and #68 in FY2024; up 16 since FY2024.
53	National Academy of Sciences Top agencies VA (Department of Veterans Affairs) OSD (Office of the Secretary of Defense) NASA (National Aeronautics and Space Administration)	$7,653,488	0.2%	Rank history: #20 in FY2021, #24 in FY2022, #28 in FY2023 and #31 in FY2024; down 22 since FY2024.
54	Excella, LLC Top agencies OPM (Office of Personnel Management)	$7,652,825	0.2%	Rank history: not on the FY2021–FY2023 lists and #53 in FY2024; down 1 since FY2024.
55	International Business Machines Corporation 2 awardees Top agencies OSD (Office of the Secretary of Defense)	$7,458,573	0.2%	Rank history: #16 in FY2021, #25 in FY2022 and not on the FY2023–FY2024 lists; returned.
56	Hart Technologies, Inc. Top agencies Navy (Department of the Navy)	$7,358,080	0.2%	Rank history: #55 in FY2021, not on the FY2022 list, #94 in FY2023 and #64 in FY2024; up 8 since FY2024.
57	Baylor College of Medicine Top agencies HHS (Department of Health and Human Services)	$7,176,349	0.2%	Rank history: #57 in FY2021, #49 in FY2022, #38 in FY2023 and #34 in FY2024; down 23 since FY2024.
58	Prometheus Hydrogen, LLC Top agencies USAF (Department of the Air Force)	$7,124,996	0.2%	Rank history: not on the FY2021–FY2024 lists; new.
59	Atlantic States Marine Fisheries Commission Top agencies Commerce (Department of Commerce)	$7,000,000	0.2%	Rank history: not on the FY2021–FY2024 lists; new.
60	Gartner, Inc. Top agencies USAF (Department of the Air Force) Navy (Department of the Navy) Army (Department of the Army)	$6,945,308	0.2%	Rank history: #27 in FY2021, #27 in FY2022, #25 in FY2023 and #17 in FY2024; down 43 since FY2024.
61	Cherokee Insights LLC Top agencies DCSA (Defense Counterintelligence and Security Agency)	$6,872,050	0.2%	Rank history: not on the FY2021–FY2022 lists, #46 in FY2023 and #41 in FY2024; down 20 since FY2024.
62	CVS Health Corporation Through CVS Healthspire Payor & Life Sciences LLC Top agencies HHS (Department of Health and Human Services)	$6,857,981	0.2%	Rank history: #66 in FY2021, #75 in FY2022, #84 in FY2023 and not on the FY2024 list; returned.
63	Group W Inc. Top agencies Navy (Department of the Navy) Army (Department of the Army)	$6,501,608	0.2%	Rank history: #69 in FY2021, #93 in FY2022, not on the FY2023 list and #61 in FY2024; down 2 since FY2024.
64	Dawson Solutions LLC Top agencies DHS (Department of Homeland Security) USDA (Department of Agriculture)	$6,240,913	0.2%	Rank history: not on the FY2021–FY2024 lists; up 227 since FY2024.
65	Universal Technical Resource Services Inc. Top agencies USAF (Department of the Air Force)	$6,239,653	0.2%	Rank history: not on the FY2021 list, #84 in FY2022, #82 in FY2023 and #78 in FY2024; up 13 since FY2024.
66	The Medical College of Wisconsin, Inc. Top agencies HHS (Department of Health and Human Services)	$6,041,662	0.2%	Rank history: #78 in FY2021, #61 in FY2022, #77 in FY2023 and #77 in FY2024; up 11 since FY2024.
67	Tanaq Management Services LLC Top agencies HHS (Department of Health and Human Services)	$5,901,914	0.2%	Rank history: not on the FY2021–FY2022 lists, #81 in FY2023 and #72 in FY2024; up 5 since FY2024.
68	S C & A Inc. Top agencies DOI (Department of the Interior) DOE (Department of Energy) NRC (Nuclear Regulatory Commission)	$5,891,219	0.2%	Rank history: not on the FY2021–FY2024 lists; up 55 since FY2024.
69	Forrester Research, Inc. Top agencies USAF (Department of the Air Force) Commerce (Department of Commerce) USDA (Department of Agriculture)	$5,887,075	0.2%	Rank history: not on the FY2021–FY2024 lists; up 94 since FY2024.
70	Bluefoot Inc. Top agencies USAF (Department of the Air Force)	$5,720,000	0.2%	Rank history: not on the FY2021–FY2024 lists; up 202 since FY2024.
71	Jacobs Government Services Company Through Jacobs Engineering Group Inc. Top agencies Army (Department of the Army)	$5,500,717	0.2%	Rank history: not on the FY2021–FY2023 lists and #79 in FY2024; up 8 since FY2024.
72	S.P. Cramer & Associates, Inc. Top agencies Army (Department of the Army) Commerce (Department of Commerce)	$5,394,283	0.2%	Rank history: not on the FY2021–FY2022 lists, #50 in FY2023 and #80 in FY2024; up 8 since FY2024.
73	Acumen LLC Top agencies HHS (Department of Health and Human Services)	$5,387,012	0.2%	Rank history: #32 in FY2021, #39 in FY2022, #43 in FY2023 and #46 in FY2024; down 27 since FY2024.
74	Applied Enterprise Management Corporation Top agencies ED (Department of Education)	$5,348,880	0.2%	Rank history: not on the FY2021–FY2022 lists, #92 in FY2023 and #30 in FY2024; down 44 since FY2024.
75	Mid Atlantic Technical and Executive Consulting, LLC Top agencies Navy (Department of the Navy)	$5,298,766	0.2%	Rank history: #95 in FY2021, #68 in FY2022, #51 in FY2023 and #45 in FY2024; down 30 since FY2024.
76	Consolidated Safety Services Incorporated Top agencies EPA (Environmental Protection Agency) DOI (Department of the Interior)	$5,212,594	0.2%	Rank history: #94 in FY2021 and not on the FY2022–FY2024 lists; up 29 since FY2024.
77	The Precision Group, LLC Top agencies DOJ (Department of Justice)	$5,192,978	0.2%	Rank history: not on the FY2021–FY2022 lists, #74 in FY2023 and not on the FY2024 list; up 36 since FY2024.
78	Information Management Services, Inc. Top agencies HHS (Department of Health and Human Services)	$5,139,912	0.2%	Rank history: #68 in FY2021, #64 in FY2022, #57 in FY2023 and #67 in FY2024; down 11 since FY2024.
79	MRIGLOBAL Top agencies DOD (Department of Defense)	$5,098,269	0.2%	Rank history: not on the FY2021–FY2022 lists, #89 in FY2023 and #81 in FY2024; up 2 since FY2024.
80	Kgsne JV II LLC Top agencies EPA (Environmental Protection Agency)	$4,972,718	0.1%	Rank history: not on the FY2021 list, #96 in FY2022 and not on the FY2023–FY2024 lists; up 77 since FY2024.
81	Dawson Mcg, Inc. Top agencies DHS (Department of Homeland Security) Army (Department of the Army) EPA (Environmental Protection Agency)	$4,959,968	0.1%	Rank history: not on the FY2021–FY2024 lists; new.
82	Groundswell Corporation Top agencies DOT (Department of Transportation)	$4,913,332	0.1%	Rank history: not on the FY2021 list, #92 in FY2022, not on the FY2023 list and #66 in FY2024; down 16 since FY2024.
83	Arctic Slope Regional Corporation 3 awardees, including Netcentric Technology, LLC and Asrc Federal Data Network Technologies, LLC Top agencies Commerce (Department of Commerce) EPA (Environmental Protection Agency)	$4,887,054	0.1%	Rank history: not on the FY2021–FY2022 lists, #63 in FY2023 and not on the FY2024 list; returned.
84	Stealth Software Technologies, Inc. Top agencies Army (Department of the Army)	$4,759,999	0.1%	Rank history: not on the FY2021–FY2024 lists; new.
85	Gryphon Technologies L.C. Top agencies USAF (Department of the Air Force)	$4,650,862	0.1%	Rank history: not on the FY2021–FY2024 lists; up 360 since FY2024.
86	Environmental Assessment Services, LLC Top agencies Army (Department of the Army)	$4,646,725	0.1%	Rank history: not on the FY2021–FY2024 lists; up 295 since FY2024.
87	Summit Consulting LLC Top agencies HUD (Department of Housing and Urban Development) DOL (Department of Labor)	$4,612,272	0.1%	Rank history: #61 in FY2021, #76 in FY2022, #76 in FY2023 and not on the FY2024 list; up 19 since FY2024.
88	Linquest Corporation Top agencies USAF (Department of the Air Force)	$4,562,645	0.1%	Rank history: not on the FY2021–FY2024 lists; new.
89	Frontier Technology Inc. Top agencies Navy (Department of the Navy)	$4,555,631	0.1%	Rank history: not on the FY2021–FY2024 lists; up 218 since FY2024.
90	ABM Facility Support Services, LLC Top agencies GSA (General Services Administration)	$4,495,032	0.1%	Rank history: not on the FY2021–FY2024 lists; up 266 since FY2024.
91	JBS International, Inc. Top agencies DOL (Department of Labor)	$4,467,777	0.1%	Rank history: not on the FY2021–FY2024 lists; up 349 since FY2024.
92	Georgia TECH Applied Research Corp Top agencies USAF (Department of the Air Force)	$4,392,092	0.1%	Rank history: not on the FY2021–FY2024 lists; up 109 since FY2024.
93	Trane U.s. Inc. Top agencies USAF (Department of the Air Force) GSA (General Services Administration)	$4,384,215	0.1%	Rank history: not on the FY2021–FY2024 lists; new.
94	Southeastern Archaeological Research Inc. Top agencies Army (Department of the Army)	$4,369,401	0.1%	Rank history: not on the FY2021–FY2024 lists; up 62 since FY2024.
95	Decision Information Resources, Inc. Top agencies ED (Department of Education)	$4,357,407	0.1%	Rank history: not on the FY2021–FY2024 lists; new.
96	Source Healthcare Analytics LLC Top agencies HHS (Department of Health and Human Services)	$4,323,354	0.1%	Rank history: not on the FY2021–FY2024 lists; up 11 since FY2024.
97	Analytical Mechanics Associates Inc. Top agencies NASA (National Aeronautics and Space Administration)	$4,310,797	0.1%	Rank history: not on the FY2021–FY2024 lists; up 21 since FY2024.
98	Ernst & Young LLP Top agencies NASA (National Aeronautics and Space Administration) EXIM (Export Import Bank of the US)	$4,268,796	0.1%	Rank history: not on the FY2021–FY2024 lists; up 121 since FY2024.
99	Techlaw Consultants Inc. Top agencies EPA (Environmental Protection Agency)	$4,198,914	0.1%	Rank history: not on the FY2021–FY2024 lists; up 10 since FY2024.
100	Neptune and Company, Incorporated Top agencies DOE (Department of Energy) DOI (Department of the Interior)	$4,158,196	0.1%	Rank history: not on the FY2021–FY2024 lists; up 80 since FY2024.

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100 of 1,745 contractors listed here. See the rest on GovTribe.

Rankings for the codes under PSC B5

Code	Net obligations	Largest contractor
B541 Defense Studies	$586,928,429	Parsons Corporation
B599 Other Special Studies and Analysis	$302,502,035	Booz Allen Hamilton Holding Corporation
B506 Data Analysis (other than scientific)	$260,173,397	Educational Testing Service
B510 Environmental Studies and Assessments	$224,994,258	Amentum Holdings, Inc.
B529 Scientific Data Studies	$141,722,409	ManTech International Corporation
B537 Medical and Health Studies	$106,346,310	Harvard Pilgrim Health Care, Inc.
B504 Chemical/Biological Studies and Analysis	$59,789,484	Merrick & Company
B507 Economic Studies	$55,219,974	Muscogee Staffing Solutions, LLC
B544 Technology Studies	$36,509,639	Gartner, Inc.
B503 Archeological/Paleontological Studies	$33,289,667	New South Associates, Inc.
B542 Educational Studies and Analysis	$29,770,126	Research Triangle Institute
B516 Animal and Fisheries Studies	$26,648,760	Atlantic States Marine Fisheries Commission
B509 Endangered Species Studies – Plant and Animal	$17,452,393	Everfox LLC
B533 Water Quality Studies	$10,375,116	Phigenics LLC
B502 Air Quality Analysis	$9,279,608	University of California, Davis
B525 Natural Resource Studies	$2,510,394	Eastern Research Group Inc.
B517 Geological Studies	$2,236,565	Athena Technologies Inc.
B534 Wildlife Studies	$2,090,984	Asir LLC

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 $3.35 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 2025 ran Oct 1, 2024 – Sep 30, 2025. 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 FY2024. "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 FY2024 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 PSC B5 contractors in FY2025?

1. Ameresco Inc. ($401M), 2. Parsons Corporation ($198M), 3. CEG Solutions LLC ($157M), 4. Johns Hopkins University ($151M), 5. The Rand Corporation ($144M), 6. Constellation Newenergy Inc. ($120M), 7. The CNA Corporation ($105M), 8. Booz Allen Hamilton Holding Corporation ($78.2M), 9. Research Triangle Institute ($75.2M), 10. Educational Testing Service ($62.8M).

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