This study addressed two issues. First, it examined the ability of two models, developed by Cox, Ingersoll and Ross (CIR), to explain the differences between futures and implicit forward prices in the thirteen-week T-bill market. The models imply that if future interest rates are stochastic, futures and forward prices differ; the structural difference is due to the daily settlement process required in futures trading. Second, the study determined the efficiency of the thirteen-week T-bill futures market using volatility and regression tests. Volatility tests use variance bounds to examine whether futures prices are excessively volatile for the market to be efficient. Regression tests investigate whether futures prices are unbiased predictors of future spot prices. The study was limited to analysis of the first three futures contracts, using weekly price data as reported in the Wall Street Journal from March, 1976 to December, 1984. Testing of the first CIR model involved determination of whether changes in futures-forward price differences are related to changes in local covariances between T-bill futures and bond prices. The same procedure applied in testing the second model with respect to changes in futures-forward price differences, local covariances between T-bill spot and bond prices, and local variances of bond prices. Volatility tests of market efficiency involved comparison of mean variances on both sides of two inequality equations. Regression tests involved determination of whether slope coefficients are significantly different from zero.

[pt] O Setor Elétrico Brasileiro sofreu diversas mudanças regulatórias ao longo da década de 90, entretanto, após o racionamento de energia ocorrido entre 2001 e 2002 observou-se a necessidade de adoção de um arcabouço regulatório mais moderno e eficiente. Dentre as mudanças implementadas pelo novo modelo, destacamos a competição livre de preços para o setor de geração e o Ambiente de Comercialização Livre como as mais disruptivas. Essas mudanças, além de incentivar a modicidade tarifária, permitiu que os agentes do setor se protegessem de variações do preço da energia elétrica por meio de contratos futuros/a termo. Diferente dos mercados desenvolvidos que possuem um mecanismo formal de livre comercialização por meio de uma estrutura de bolsa centralizada, o Brasil ainda mantém um mercado informal através de uma estrutura de balcão descentralizado. Esse quadro resulta em uma falta de transparência nos preços, e que gera dificuldade na obtenção de dados e análise assertiva do comportamento do mercado futuro/a termo de energia elétrica brasileiro. O crescimento do mercado a termo brasileiro, em tamanho e importância, registrado nos últimos anos justifica a necessidade de aprofundamento das análises desse mercado. O objetivo deste trabalho é compreender o comportamento dos preços a termo em relação ao preço esperado à vista futuro a partir de uma metodologia de coleta de dados de mercado. O resultado do estudo aponta comportamento de contango para os contratos de 2017 com maturidade para 2018. O resultado é aderente a estudos realizados em mercados maduros para contratos com tempo de maturidade reduzido. / [en] The Brazilian Electricity Sector has undergone several regulatory changes throughout the 1990s, however, the energy rationing between 2001 and 2002, showed the need to adopt a more modern and efficient regulatory framework. Among the changes implemented by the new model, the free competition prices for the generation sector and a Free Trading Environment stands out as the most disruptives. These changes, as well as encourage tariff modicity, also allowed the players to hedge against changes in the electricity prices through futures/forward contracts. Unlike developed markets that have formal mechanism for free trading through a centralized stock exchange structure, Brazil still maintains an informal market through a decentralized counter structure, this situation results in a lack of transparency in the prices that generate difficulty in obtaining data and assertive analysis of the Brazilian futures/forward market behavior. The growth of the Brazilian forward market, in size and importance, recorded in recent years, justifies the need to deepen the analysis of this market. The objective of this paper is to understand the behavior of forward prices in relation to the expected future spot price based on market data collection methodology. The result of the study shows a contango behavior for the contracts of 2017 with maturity to 2018. The result is adherent to studies conducted in mature markets with reduced maturity time contracts.