Clothing retailer Supergroup posted a 2% rise in pre-tax profit and said it has signed a joint venture that will allow it to enter the Chinese market.For the year ended 25 April 2015, the owner of the Superdry street fashion label reported underlying pre-tax profit of £63.2m versus £62.0m in 2014, on revenue of £486.6m, up 12.9% from £430.9m.The company said the year was a "game of two halves" as extremely mild weather conditions last year impacted revenue in the first half of this year, while in the second half, trading improved significantly as promotional activity, renewed focus on product and improved processes began to gain traction.In the first 10 weeks of the current financial year, retail revenues increased 34.5% year-on-year, with retail like-for-like sales growth of over 20.3%, the company said.Like-for-like revenues grew 4.8% in the year and gross margin 120 basis points higher.Confirming recent rumours, the company also said it has signed a joint venture with Trendy International Group in China.Chief executive officer Euan Sutherland said: "Despite a challenging start to full-year 2015 the business made good progress in the second half of the year, delivering healthy sales growth, developing our infrastructure and continuing to advance our product range as we incorporate extensive customer insight into our design process."