The paper presents the results of computer simulations performed using the historical quotes on several securities (WIG20, S&P500, Dow Jones, DAX, EUR/USD, gold, oil, etc.) in order to analyse the possibility of finding such variables, that can be explained in terms of the others better, than the rest. It is assumed, that the ultimate goal of every investment strategy is finding the opportunity of gaining a financial profit (always considering the risk). Such opportunity is being sought by investigating the possibility of using each variable (each security) in turn as the one to be predicted. In order to reach that goal, authors use several variants of one of the algorithms belonging to the. Group Method of Data Handling (GMDH), namely the combinatorial algorithm. The results reveal some interesting features of regression models, indicating the prospect of further applications of the method.