Dimensional Fund Advisors works on the largest US stock market. According to Dimensional's philosophy, "it is certainly possible to outperform the markets, but not without accepting increased risk." (Market work, Dfaus.). Does this market agree with the market efficiency hypothesis, clearly putting an end to market attempts according to weak, semi-strong and strong forms of efficiency? American market situation. In fact, Dimensional Fund advisors work in the technically and managerially advanced US market. However, “today, most financial markets appear semi-strong at best.” (Robert E. Wright, Vincenzo Quadrini). A semi-strong market means that all publicly available information is included in prices and no fundamental analysis may be necessary. Promising benefits. Although market prices may represent the most relevant information about stocks, it is not so easy to correctly interpret this information. There is no doubt that only a sufficiently large sample of the number of funds can present the key information. Only a benchmark can correctly measure the efficiency of market functioning. One more fact to support the work of Advisor Funds – skewed statistics, this fund is one of the surviving funds that still produces better results than many non-surviving funds. Possible risks. According to James L. Davis, these risks can be summarized as the predictability of returns, the linkage of the financial market to the real economy, and the persistence of performance. Predictability of returns means that the investor can estimate only the average time and stock return, with little emphasis on predicting the exact time or stocks. name most likely to change. Link of the financial market with the real economy. Very often, markets are sensitive to many variables, for example the most effective managers with an SAT score above 1420, however according to "the Chevalier and Ellison manager characteristics model can only explain about 5% of the total variation in mutual fund returns” (James L. Davis), because the style-adjusted passive benchmark model was found to be more effective in operating the average mutual fund than the active model (James L.Davis). Performance persistence. Most of the information is provided in prices and most management efforts simply cannot overestimate the market. In fact, the more efficient the market, the less the services of market experts are needed. What is the model? Certain variables can be used to predict returns, such as stock characteristics (size, book value and market value); however, it is not clear whether these are abnormal returns or just some variations in returns..