The pricing of financial assets, this paper contends, it does not consist only in assessing a technical value from a valuation model and then calibrating such value by looking at the market. In order to sharpen up this complex process we are going to handle, firstly, a valuation procedure that stems from the temporal structure of rates of return adjusted for risk. Secondly, the concept of the physical world of finance is introduced just to move further onto the cost-profit structure of dealers and big players, highlighting the far-reaching role of transaction costs.