After a re-rating Diageo's stock as "underperform" since the completion of Pillsbury and the regulatory ratification of the acquisition of the Seagram assets, WestLB Panmure believes that a further re-rating is not possible without further re-restructuring.  The bank explained that its mathematical modelling of ready-to-drink (eg, Smirnoff Ice) product life cycles shows that the growth of this category is not as bullish as the market seems to expect. The rapid entry of a whole host of new products means that growth and margins should start to wane.