This thesis aims to analyse the financial statements of key companies within the energy sector, providing insights into their financial stability, efficiency, and competitiveness in the market. Special emphasis is placed on changes resulting from the restructuring of the electricity system, including liberalization, deregulation, and privatization processes, as well as the impact of these changes on market dynamics and the business operations of energy companies. The liberalization of the energy sector enables consumers to freely choose their suppliers, which contributes to increased market competition and a reduction in electricity prices. On the production side, privatization increases competition, thus driving the transition of the electricity system towards a horizontally integrated model. This model aims to ensure a more sustainable and efficient energy system. In the empirical section of the thesis, a financial analysis is conducted, which includes an overview of key performance indicators such as profitability, liquidity, debt, and efficiency. These indicators provide insights into the ability of energy companies to adapt to changing market conditions and identify key risks and opportunities within the industry. Based on the financial statement analysis, the thesis concludes that changes in the regulatory framework and market conditions in the energy sector have contributed to increased efficiency and competitiveness but have also raised demands for adaptation and strategic risk management for companies in the energy sector.