In the Brazilian wholesale electricity market, power generators and large consumers negotiate long-term contract prices freely. However, sophisticated computational models evaluate the energy market price, or Difference Settlement Price (DSP). Hydrothermal dispatch optimization models drive these computational models, so market forces do not directly impact market prices. Four electrically interconnected submarkets break down the National Interconnected System (NIS) -Southeast, Northeast, North and South. Considering the historical energy prices, all these submarkets showed anti-persistence behaviour (or meanreversion) and multifractality, aligning with various studies conducted in other markets worldwide. The South submarket exhibited the highest multifractality and lowest efficiency, while the North submarket showed the lowest multifractality and highest efficiency. We also investigated the behaviour of the Hurst exponent and Long Memory Magnitude over time using sliding windows. All submarkets showed anti-persistence behavior throughout the evaluation period, with the South submarket displaying higher volatility in the efficiency index. The Northeast and North submarkets showed a downward trend in their indices over the period, indicating increased efficiency. These findings, while preliminary and requiring further in-depth analysis and consideration of other factors, offer valuable insights for decision-makers and regulators pursuing new market arrangements to boost efficiency.INDEX TERMS Brazilian electricity market, multifractal detrend fluctuation analysis, generalized hurst exponent, anti-persistence, singularity spectrum, market efficiency.