Decision-making under Market Indeterminacy

The Efficient Markets Hypothesis (EMH) is the focusing topic in the past 50 years of financial market researches. Many empirical studies are then provided that want to test EMH but have no consensus. The perception of EMH determines the attitude and strategy of participants and regulators in financial market. One perception of EMH argues that investors’ behavior of seeking abnormal profits and arbitrage drives prices to their ‘‘correct’’ value. Investigating the “correct” value derives the concept of “market indeterminacy”. It means the inability to determine whether stock prices are efficient or inefficient. Market indeterminacy pervades stock markets because “correct” prices are unknown because of imperfect information and model sensitivity. Market indeterminacy makes arbitrage risky and makes event studies unreliable in some policy and litigation applications. The concept of market efficiency is needed to be re-recognized considering the mechanism of price formation. In order to further research and practice in law and financial market, there needs a view from the “jumping together” of disparate disciplines. Adaptive Markets Hypothesis(AMH) that using the evolutionary principles in financial market is a new viewpoint oncognitive decision and deserves to be paid more attention to.