** Shares of British online fashion retailer ASOS Plc down >3% after UBS downgrades to "neutral" from "buy"
** In a note titled "Growth, but at what cost?" UBS says it is more cautious on the level of margin investment required to drive FY sales growth
** Says over the past 6 months, changes to pricing, promotions and newness have significantly impacted ASOS's top-line and margins
** "Improving customer acquisition through higher 'newness' and more competitive pricing supports its above cons. FY19 top-line forecast (UBSe ~17%, cons. ~16%), but the cost of growth doesn't seem to be easing," UBS says
** Says sees no evidence yet that ASOS is pricing up to offset higher promotions, so margin pressure could continue into H1 2020 before annualising
** UBS says "turning more positive on top-line growth, but less positive on margins," cuts PT to 3,300p from 3,500p