As it is widely known, according to the efficient market hypothesis (EMH), for rational behavior and market efficiency there is no information in the trading history of an asset that leads to arbitrage opportunities [1]. Nevertheless, a large number of market players are engaged in obtaining such information: in fact, although fundamentalists hold most of stocks, technical traders contribute to the majority of the volume traded [2]. This discussion includes the definition of market efficiency and a non-trivial analysis of market agents rationality; seminal ideas are found in Refs. [3–۵]. Fundamental contributions to understanding market dynamics have been developed in the context of behavioral economics and finance, where irrational behavior is studied in detail [6, 7], and in experimental approaches to economics, where the conditions for the market to evolve as predicted by economic theory are investigated [8, 9]. Adaptive market hypothesis [10], which asserts that the market evolves according to natural selection of bounded rational agents, permits return predictability from time to time, and has been argued to furnish satisfactory explanation in some cases.