Before information φ arrives, market observers must be uncertain whether the stock price conditioned on φ will be higher or lower than the current price. Otherwise there is an obvious arbitrage opportunity. By assuming this minimal condition of efficient markets, it is shown under the...

The term "information risk" or "information uncertainty" is defined as the risk of a misleading signal. This risk is understood Bayesianly in terms of the likelihood function f(S|φ). In Bayesian method, f(S|φ) captures the quality of signal S with respect to parameter φ. The Bayesian position...