Companies are the economic units that generate economic growth for any country or region by offering the goods and services demanded by society at the same time that they generate a large number and variety of jobs, specifically the micro companies belonging to the sector of the professional, technical and scientific services in Mexico contribute with a significant number of companies and employment generated. The Capital Asset Pricing Model requires the estimation of Beta risk coefficients and has been applied in a general way to large companies belonging to developed countries. The present work is focused on developing an own index of micro companies in Mexico and determining the respective risk coefficients for nine economic branches of the mentioned subsector. The final results made it possible to identify the nine Beta coefficients for the chosen branches of the professional, scientific and technical services sector, in such a way that said risk indicators can be used to calculate the value and risk associated with the micro-companies of said branches of the economy in Mexico; providing a valuation alternative to improve access to financing.