These Houston-based companies are predominantly large corporate groups, many of which operate internationally. They represent a mix of sectors, including energy, manufacturing, and services. Notable examples include NRG Energy, providing natural gas and electricity solutions, and Tailored Brands, Inc., focused on retail apparel. Westlake manufactures petrochemicals and building products globally, while Noble Corporation is an offshore drilling contractor. Quanta Services, Inc. offers integrated solutions for electric power and pipeline industries, and Corebridge Financial provides retirement and insurance products.
A significant pattern observed among these companies is their strong presence in the energy sector, particularly oil and gas, with several firms like Noble Corporation, Helix Energy Solutions Group, and Parker Wellbore specializing in offshore drilling and energy services. Additionally, there is a notable cluster of companies in the construction and building materials industries, such as Quanta Services, IES Holdings, Comfort Systems USA, and Quanex.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
NRG Energynrg.com
Provides innovative natural gas, electricity, and smart home energy solutions to a diverse range of customers across North America. |
16,171 | |||
| 2 |
Tailored Brands, Inc.tailoredbrands.com
Company focuses on enhancing customer appearance and confidence for important moments, emphasizing inclusivity, integrity, teamwork, and continuous improvement. |
11,474 | |||
| 3 |
Westlakewestlake.com
Manufacturing and supplying petrochemicals, plastics, and building products globally, enhancing daily life through quality products and services. |
6,574 | |||
| 4 |
Noble Corporationnoblecorp.com
Leading offshore drilling contractor operating advanced fleet focused on ultra-deepwater and high-specification jackup drilling worldwide. |
6,572 | |||
| 5 |
Quanta Services, Inc.quantaservices.com
Leading specialty contractor offering integrated solutions and skilled workforce for electric power, pipeline, industrial, and communications industries across North America. |
6,263 | |||
| 6 |
Corebridge Financialcorebridgefinancial.com
A leading provider of retirement solutions and insurance products, empowering people to take action for a secure financial future |
5,319 | |||
| 7 |
U.S. Physical Therapy, Inc.usph.com
A publicly held company with hundreds of outpatient therapy clinics in 41 states, offering care for orthopedic and neurologic disorders through unique partnerships |
4,246 | |||
| 8 | 4,121 | ||||
| 9 |
IES Holdingsies-co.com
Electrical contracting services for commercial, industrial, residential, and infrastructure sectors across the United States, based in Houston, Texas. |
2,868 | |||
| 10 |
KBR Careerscareers.kbr.com
Global provider of science, technology, and engineering solutions to governments and companies, delivering value-added services and operations in 33 countries |
2,732 | |||
| 11 |
CraftWorks Restaurants & Breweries, Inc.spbhospitality.com
A leading operator and franchisor of full-service dining restaurants with a diverse portfolio including national restaurant and brewery brands |
2,729 | |||
| 12 |
Helix Energy Solutions Grouphelixesg.com
An international offshore energy services company based in Houston, specializing in well intervention, robotics, and decommissioning operations to support global energy transition |
1,952 | |||
| 13 |
Parker Wellborenabors.com
Wellbore construction partner minimizing risk & optimizing performance Specializing in drilling, rig operations, rental tools, and supporting customers in energy transition |
1,622 | |||
| 14 |
Comfort Systems USAcomfortsystemsusa.com
National HVAC company with 30 years of experience offering complete HVAC services for a wide range of buildings, from schools to high-rises and industrial plants |
1,497 | |||
| 15 |
Quanexquanex.com
A global manufacturing company focused on innovation, efficiency, community impact, shareholder value, and employee development in various markets worldwide |
1,420 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 16 |
ORIONoriongroupholdingsinc.com
Specializing in marine, concrete, and engineering services, providing construction solutions across the United States, Canada, and the Caribbean with predictable excellence |
1,136 | |||
| 17 |
Boardwalk Pipelinesbwpipelines.com
A midstream natural gas and NGLs company providing transportation, storage, and customer service with over 14,000 miles of pipelines and underground storage caverns |
1,116 | |||
| 18 |
HILONG GROUP OF COMPANIEShilonggroup.com
Specializing in oil and natural gas industries, this group of enterprises has subsidiaries with production bases in multiple locations worldwide |
1,115 | |||
| 19 | 1,013 | ||||
| 20 |
Lexitaslexitaslegal.com
Provider of professional services and technology solutions for legal, insurance, and corporate sectors, ensuring accuracy, timeliness, and reliability for vital outcomes |
890 | |||
| 21 |
Bredero Shawtenaris.com
The company is rebranding to Shawcor and specializes in providing updates and news regarding their transition and evolving brand |
871 | |||
| 22 |
Par Pacific Holdings, Inc.parpacific.com
An energy company based in Houston, focusing on renewable and conventional fuels, with refining, logistics, and retail operations in the Western United States |
780 | |||
| 23 |
TNT Crane & Rigging, Inc.tntcrane.com
A leading crane service provider in North America, offering safe and specialized lifting solutions for various industries with a modern fleet of 700+ cranes |
777 | |||
| 24 |
Piping Technology & Products, Inc.pipingtech.com
Manufacture high-quality engineered pipe supports including hangers, expansion joints, pre-insulated supports, custom designs, and emergency solutions for various industries. |
727 | |||
| 25 |
Worldwide Oilfield Machinewomgroup.com
Multinational equipment manufacturer specializing in solutions for drilling, testing, production, and intervention operations in various environments globally with a diverse workforce |
668 | |||
| 26 |
Carriage Servicescarriageservices.com
A leading provider of professional funeral and cemetery services in the United States, committed to high quality, ethics, and client care nationwide |
666 | |||
| 27 |
TMK IPSCOtenaris.com
Specializing in oil and gas technologies, the company contributes to the industry through its integration with Tenaris |
601 | |||
| 28 |
Saber Powersaberpower.com
Engineering-led professional services company specializing in medium and high voltage electrical infrastructure Offering turnkey EPC, construction, maintenance, emergency response, training, and engineering services globally |
597 | |||
| 29 |
Nova Medical Centersconcentra.com
Occupational healthcare provider offering drug testing, physicals, work-injury care, and physical therapy for on-the-job injuries to exceed patient and client expectations |
588 | |||
| 30 |
Meriplexmeriplex.com
A provider of managed technology solutions specializing in Intelligent WAN, Cybersecurity, Physical Security, Cloud, and Voice services for enabling business transformation and growth |
587 | |||
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How this list is built
Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 11, 2026.
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