Sweeney [207] offers several potential explanations of the profitability of the filter rules. First, they can be interpreted as evidence against the static capital asset pricing model in which case they might be consistent with alternative explanations of risk and return. Second, they may be evidence of market inefficiency and insufficient speculative capital. Third, they may represent profits that are available to speculators because of central bank intervention which systematically loses money by leaning against the wind.