"> modeling a particular market force that has been difficult to capture in previous models. Empirical evidence shows that, when a stock return is fluctuating i

"> modeling a particular market force that has been difficult to capture in previous models. Empirical evidence shows that, when a stock return is fluctuating in the short term, there exists a market force that draws the fluctuating stock return back to its long-run equilibrium. This force is related to the concept of mean reversion, which is the tendency of a stock to return to its average price." Talk of "market forces" and the like fall into the quantum voodoo school of economics, IMHO.