Design/methodology/approach: The research method used in the article is a critical analysis of the related literature on the basis of many studies and reports available on the market. Findings: The results of the literature review are the basis for statements about shadow banking in the financial sector. Other research should be devoted to the analysis of the stability of the financial system during the COVID-19 pandemic, because there will be many other factors that affect the functioning of banking or non-banking entities and also shape new directions of their development. Research limitations/implications: The review was limited to reports of the National Bank of Poland, the Polish Financial Supervision Authority and the Central Statistical Office (now Statistics Poland) only due to the necessity to standardize the sources of publication of research results. Originality/value: Conclusions from the review may inspire others to undertake research in previously unexplored areas. They may also be a guide to ensure its best possible quality.