Standard Industry Classification (SIC) codes are four-digit numeric codes that classify the industries to which companies belong based on their business activities.
Standard industry classification codes have largely been replaced by the six-digit North American Industry Classification System (NAICS).
Despite the replacement, government agencies, including the SEC, and some companies still use SIC codes.
The first two digits represent the highest level business class, and the next two digits are used to refine identification.
The government uses SICs to assign review of financial documents to the appropriate departments to ensure that all requirements are met.