Online supermarket Ocado saw its shares come under pressure as it revealed a slowdown in trading and dashed hopes once more of a long-awaited international deal. The group shrugged off a "challenging and competitive" market to deliver a 13 per cent rise in fourth quarter gross retail sales to A 351.8 million - its 13th quarter of double-digit growth - but this was lower than expectations and below the 15.3 per cent hike seen in the previous three months.