Emerging markets are a special group of countries that do not have a sufficiently long and continuous financial history. Therefore, they require special approaches when justifying methods and instruments for investment analysis. In this context, the paper addresses the issue of public companies' assessment and diagnostics revealing advantages and limitations of public status, challenges of market value assessment and controversial issues of corporate financial health evaluating. Obtaining and maintaining the public status provide various benefits for a company increasing its opportunities to attract financing and diversify risks. Negative consequences of public status contain corresponding costs, lack of confidentiality, and raised external risks. For emerging markets, the last two become quite significant. We also argue that emerging markets challenge business assessment due to the actual lack of an open, competitive and transparent market. In this regard, it should be more reasonable to apply the standard of investment value even when it comes to public companies. As for financial diagnostics, we suggest that it should efficiently combine relevant micro and macro approaches. Such synthesis allows revealing major controversial issues related to public companies on the emerging markets. Therefore, we propose to develop the financial diagnostics methodology in the frame of financial crises and financial stability conceptions.