Analysis
NAICS 551 is the 2022 subsector for management of companies and enterprises, part of 55 (Management of Companies and Enterprises).
It has only one more detailed code, 55111, which covers exactly the same activities; the definition, index entries and statistics are on that page.
County Business Patterns counts 49,556 US establishments in this code in 2023, employing 3,855,720 people at an average annual payroll of $128,997 per employee (93rd percentile of national industries). 37% of the establishments have fewer than five employees, which is close to the national mix.
Between 2018 and 2023 the number of establishments fell 9% and employment rose 9%. The 2018 count used NAICS 2017, so part of a large move can come from codes being redefined rather than from businesses opening or closing.
Official definition
Industries in the Management of Companies and Enterprises subsector include three main types of establishments: (1) those that hold the securities of (or other equity interests in) companies and enterprises; (2) those (except government establishments) that administer, oversee, and manage other establishments of the company or enterprise but do not hold the securities of these establishments; and (3) those that both administer, oversee, and manage other establishments of the company or enterprise and hold the securities of (or other equity interests in) these establishments. Those establishments that administer, oversee, and manage normally undertake the strategic or organizational planning and decision-making role of the company or enterprise.
Source: US Census Bureau, NAICS 2022 Manual.