Online grocer Ocado sank after revealing that it had to operate "under capacity constraints" at its Hatfield distribution centre in the fourth quarter. Profit margins had been hit by production issues as well as the cost of employing extra staff as it installed further capacity, the company said.Shares were over 12% down by mid-afternoon, not helped by broker Panmure Gordon which said it expects the competitive environment to get tougher in the future. "We don't see Ocado as anything special, so it should not be valued as such," said analyst Philip Dorgan.JD Sports Fashion was the high riser, jumping nearly 10% following a tough month for the high streets sports retailer. Shares took a tumble in late November after the firm said that the growth of like-for-like sales had slowed down since the end of the first half. Nevertheless, the stock was obviously in demand today. JD said in its last trading update that while the full-year performance is "substantially" dependant on the key Christmas period, full-year earnings should be in line with expectations. On the rise was infrastructure firm Balfour Beatty after a joint venture (between it and CLG Developments) was awarded a nine-year gas networks contract in the Republic of Ireland worth £414m.Henderson Group, the investment management company, sold its share of the Hermes private equity fund, but shares fell despite the firm assuring that "There is no gain or loss for the group on disposal of its interest for cash."Capital & Counties Properties rose after entering into an agreement with some members of the Kwok family to form a 50:50 joint venture (JV) to redevelop its interest in and around Seagrave Road, London. Each party will own a 50% share of the JV, with Capco's interests valued at £131.2m. Total developments costs of the scheme are expected to be around £300m. Meanwhile, investors of Travis Perkins were pleased after the builders merchant promoted current chief operating officer John Carter to deputy chief executive, with effect from 1 January 2012.BCFTSE 250 - RisersJD Sports Fashion (JD.) 655.00p +9.53%Afren (AFR) 82.85p +5.81%Domino Printing Sciences (DNO) 508.50p +5.56%Provident Financial (PFG) 947.00p +3.22%Galliford Try (GFRD) 455.80p +3.19%Booker Group (BOK) 71.45p +2.95%Kier Group (KIE) 1,340.00p +2.92%Ashtead Group (AHT) 215.70p +2.91%Northgate (NTG) 197.10p +2.76%Mitchells & Butlers (MAB) 235.70p +2.70%FTSE 250 - FallersOcado Group (OCDO) 62.50p -12.22%Aquarius Platinum Ltd. (AQP) 151.00p -5.62%COLT Group SA (COLT) 87.20p -5.01%Carpetright (CPR) 492.10p -4.72%Jupiter Fund Management (JUP) 214.50p -4.45%Allied Gold Mining (ALD) 141.20p -4.21%CSR (CSR) 179.50p -3.86%SDL (SDL) 622.00p -3.57%Phoenix Group Holdings (DI) (PHNX) 504.50p -3.54%Kesa Electricals (KESA) 60.35p -3.52%