This paper provides an empirical analysis of FTSE100 stock returns during the period of 2009 to 2013 with an aim to assess the relevancy of Fama- French three factor model post financial crisis of 2008. FTSE100 index was chosen in particular as it is benchmark of the prosperity among UK stocks. Assortment of six portfolios S/L, S/M, S/H, B/L, B/M and B/Hbased on firm‟s size and book-to-market ratio was constructed as per gudielines of Fama- French model. The ordinary least square estimation showed consistently positive and significant in all observed portfolios.However the results indicated that excess market return is the dominant variable among three risk factors meanwhile size factor (SMB) was significant while explaining only small-scale portfolios returns but had no effect on the average returns of large-scale portfolio. Likewise value factor (HML) appeared to be somewhat effective only in case of high book-to-market stock portfolios. Thus the impact of book-to-market value on the average excess returns of these observed portfolios behave in an un-systematic manner.