Asset pricing with idiosyncratic risk: The Spanish case

Idiosyncratic risk has been the subject of a great deal of international financial research. However, one question remains unsolved thus far: how to introduce it in asset pricing models. The aim of this paper is two-fold. Firstly, we propose and compare two alternative implications of idiosyncratic risk in asset pricing: (i) as a friction or (ii) as a source of another kind of systematic risk un-captured by beta coefficient. Secondly, we improve the international empirical evidence with an in-depth analysis of the Spanish stock market over the period 1987–2007. Our findings have important implications for portfolio and risk management.