| Abstract | In this paper, the event numbers of countinuous single-direction trends of Shanghai Stock Exchange Composite Index(SSEC) have been complied, analyzed and than compared with a benchmark contribution generated under Random Walk Hypophysis. The result reveals that, generally speaking, real series contains fewer samples of countinuous single-direction trends than the contribution expected, and as the length of such tends protracted,their differences aggrandized significantly. All these samples are counted under daily data. However, when we count the number of countinuous single-direction trends in the span of week and month, the differences above-mentioned vanished. It is believed that the overeact impulses of the market based on the information brought by the endogenous price series induces this aberration ,which is different from the traditional considered overeaction based on the exogenous information. Besides, a rough examination on other foreign markets does not comfirm such aberration, which may imply specific differences in disposition between foreign markets and the domestic. |