Mario's a deep thinking lad from Italy and this is what we talked about. Dear Mr. Duncan I am an Italian student from Rome university and I am doing my final dissertation on cost of capital for telecoms and on the different approaches in calculating WACC. I was wondering if it was possible to have some research on the differences between the different CAPM's models (linear, non-linear and multifactors models). I found a study done by Wright, Mason and Miles on the subject but it seems to have a very statistic view about the CAPM's models. Could you please, if possible send me any presentation (power point) or study that explains in a more economic way why we should use a model rather then an other to better calculate the cost of capital for telecoms? Thank you in advance for all your patience and help Best Regards Mario I asked for a bit of time! Dear Duncan, I think that the only parameters that can vary are beta, risk free and ERP. What evidence can I use to make these parameters vary? Is it possible? Which are the latest methods for estimating the risk-free rate and ERP? There's some debate on-going as to what both have been doing recently, after a long period over which the ERP appeared to be stable. There's considerable room for disagreement about betas, related to the standard criticisms of the CAPM, and also disagreements about what frequency of data to use, whether to include parts of firms that are overseas or regulated, and so on. In contrast to all this, the debt-based component of the WACC is relatively straightforward to calculate; although regulators are suggesting that optimal rather than actual capital structure should be used for calculating the WACC for regulatory purposes. Thank you again Best Regards Mario Here's what I found: Dear Mario, I am sorry to be late but I have had a web site crisis! Anyway, I don’t know how much I can help but here are a few resources I have found on the CAPM: Revisiting The Capital Asset Pricing Model by Jonathan Burton looks non statistical at least but it is a bit old now! Aimed at investors so it is general but it has some graphs and basic formulae. Again for investors but with some additional links to people who seem to be important in this area business.com has a fair number of articles that you can access and I think at least some of them will be useful. Here’s a rather cheesy CAPM calculator but take a look at the links on the right hand side of the page! This is probably too basic for you but ... A mighty PDF file from Canada called The Capital Asset Pricing Model: Equity Risk Premiums and the Privately held Business. Another one from Canada This might be a useful link for you: to someone’s Blog! Worth a try: strike up a conversation with him at least! Specifically for telecoms, I found one, two (this is just a summary, though), three (79 pages from London!), four (Australian) and five , a whopping 154 pages from OFTEL in the UK I hope that’s enough to get you started, Mario. Let me know if you think I can help in any other way. Best wishes DW