The aim of this study is to reveal the financial structure of 36 companies operating in the Electricity, Gas and Water (EGS) sector on Borsa Istanbul over the period 2020–2024 by using ratio analysis and a composite index (general financial soundness index) approach. The rapid increase in energy demand, high capital requirements, regulatory pressure and a debt-based financing structure make the sector’s financial fragility a strategic area of investigation. In the study, 13 key ratios covering liquidity, profitability, capital structure and activity were transformed into the 0–1 range through Min–Max normalization; four sub-indices were then derived from these ratios and, ultimately, a Financial Soundness Index (FSI) was constructed. The findings indicate that the sector hit a “bottom” in 2020 with high leverage and weak profitability, that the FSI reached its highest level in 2022 thanks to a decline in debt ratios and a peak in profitability, and that in 2024 balance-sheet resilience was preserved despite a weakening in profitability, mainly due to a strengthened equity base. The distribution of FSI values clusters around the 0.30–0.60 band, suggesting that the EGS sector as a whole exhibits a medium-to-high level of financial soundness, but does not display a homogeneous structure at the firm level. The analysis groups firms into three profiles as financially “improving,” “deteriorating” and “stable,” thereby making visible how risk and resilience cluster within the sector. By combining traditional ratio analysis with a composite financial soundness index, the study provides an original “financial soundness map” for the EGS sector and proposes an analytical framework for policymakers, investors and creditors.