The planned incorporation into the Polish legal system in the near future and, consequently, the introduction of Companies Investing in Real Estate Leasing or Rental (FINN) into the Polish capital market will result in an institutional change within the financial system. Similarly to closed-ended investment funds and real estate joint-stock companies, the FINN companies will specialize in investing capital in the residential real estate market, and later perhaps also in the commercial real estate market. The principles of FINN’s activities included in the legislative draft are modelled directly on the legal regime of the Real Estate Investment Trust (REIT), therefore, they will be subject to numerous prohibitions and limitations, introducing organizational controls and restrictions to the investments, which however is rationally justified. These procedures aim at creating an entity with a structure of a relatively neutral, passive real estate broker or intermediary, focused solely on generating benefits for investors-shareholders. The initiation of the FINN market in Poland, and thus the scale of the ensuing institutional change, will be determined by the inclination of joint stock companies from the WIG-Nieruchomości index (Warsaw Stock Exchange Real Estate Index) to transform into FINN companies. In turn, this inclination will be determined by the conditions of institutional change – mostly of a legislative and market-driven character. With this in mind, the aim of this study is to conduct a preliminary analysis of the conditions of institutional change and present a forecast of the development potential of the WIG-Nieruchomości companies, which, due to their very similar scope and form of activity, constitute the main functional basis for the emergence of the FINN market as a new, separate segment of the capital market in Poland.