Industrial classification systems provide codes which can help to create a list of companies within the same industry. Data Axel Reference Solutions is a good starting point.)
What are SIC and NAICS Codes?
Standard Industrial Classification. (SIC) In the 1930s, The U.S. Standard Industrial Classification was developed to classify and compare industries by their principle economic activities. This 4 digit system placed activities in hierarchical categories. While SIC codes are still prevalent; The SIC Code was replaced in 1997 by the North American Industry Classification System (NAICS).
The first two numerals of the SIC Code identify
45 Transportation by Air
451 Air Transportation, Scheduled, and Air Courier Services
4513 Air Courier Services
North American Industry Classification System (NAICS.). (“NAKES”). In 1997, NAICS replaced the SIC as the industry classification system. NAICS is a new 6 digit economic classification system that makes data comparable across Canada, The United States, and Mexico. The first two numerals identify a major economic sector, the third identifies a more specific sector of the major group, the fourth represents an industry group, the fifth shows the industry, and the sixth designates the national industry.
48-49 Transportation and Warehousing
492 Couriers and Messengers
492110 Air Courier Service
What are Global Industrial Codes?
Established in 1999 by Standard and Poor's, Global Industrial Codes Standards will have 10 sectors and be followed by 24 industry groups.
See Investopoedia.com for further details.
Excellent beginning location to find SIC and NAICS codes