Online fashion retailer Asos impressed investors on Thursday as it beat fourth quarter forecasts to wrap up the year in style.Chief Executive Officer Nick Robertson said pre-tax profits for the year ended August 31st would be "marginally" above expectations.The AIM-listed company lifted retail sales 47% to £208m in the fourth quarter to produce a 40% increase to £754m for the full year, supported by rapid growth in Europe and the US. Jefferies International was one of many brokers to recommended a 'buy' rating and it issued a target price of 6,200p following the report."The trading update today demonstrated robust revenue growth, +46.4% for the fourth quarter, +33% for the first half - ahead of consensus expectations for full year (FY) 2013 at +37%. The 1:5:5 aspiration very much in play, drives consensus FY15 earnings per share to 86p," the broker said. "So what happens to the stock now? Suspect we need the FY13 numbers and associated communication to get much more excited; directors selling into the imminent long-term incentive plan vesting may crystallise something of a buying opportunity."Shares surged 9.70% to 5,302p at 10:56.RD