Financial transparency, including transparency of transactions, is one of the pillars of sustainability. This study investigates whether a company’s ownership structure, including ownership concentration, managerial ownership, and the presence of institutional investors, affects upward real earnings management practices. The research is based on companies listed on the Warsaw Stock Exchange in Poland adapting panel data regression models. The significance and contribution to literature of the paper lies in the fact that we provide evidence that the association between the magnitude of total upward real earnings management and shareholder concentration is U-shaped, thereby indicating that there is an optimal level of ownership concentration, minimizing the magnitude of upward real earnings management and thus increasing financial transparency. Our results show the negative relationship between total upward real earnings management and managerial ownership, thereby we confirm the alignment of interest hypothesis, in terms of real earnings management. We also confirm that individual instruments of real earnings management are linked to ownership concentration and managerial ownership in specific ways. The presence of institutional investors reduces the magnitude of total upward real earnings management.