A key task in ensuring the viability of enterprises is the constant monitoring of their financial condition. Due to significant dynamics of the business environment and the lack of sufficient research on minimising the negative consequences thereof, there is an urgent need to study this issue. We assumed that the selection of several main indicators of enterprise activity is sufficient for the initial assessment of the level of financial security. Given these facts, the purpose of this study is to develop a method for the express assessment of financial security of an enterprise by forming a 3D matrix, which will facilitate the rapid identification of possible threats and the application of necessary measures. The developed matrix is formed on the basis of reasonably selected indicators, in particular financial stability, profitability, and liquidity. The calculations were carried out for Ukrainian enterprises grouped by the type of their economic activity. As a result, they were classified by the level of their financial security, with groups of most companies being at an acceptable level. This method may be a tool at the initial stage of estimation of possible threats to financial security. The results of the study are important for the evaluation of the financial security of enterprises in the short term and the ability to take timely measures to counteract possible threats.