Thomas Cook stormed its way to the top of the leaderboard after Frank Meysman moved into the upper echelons of the notoriously short list of famous Belgians by being named as the new chairman of the travel group. The 59-year-old Meysman will replace current chairman Michael Beckett when Beckett retires at the beginning of December. Ocado was still heading south after Tuesday's news that UBS had cut its target price from 170p to 150p to reflect capacity constraints at its Hatfield depot as well as higher customer service costs. In a double whammy, rumours have surfaced that Tesco's will launch a new price offensive, which analysts predict will hit Ocado hardest of the grocery firms. FTSE 250 - RisersThomas Cook Group (TCG) 43.87p +6.09%Cookson Group (CKSN) 470.40p +5.85%Bellway (BWY) 636.00p +4.95%Bovis Homes Group (BVS) 424.50p +4.66%Imagination Technologies Group (IMG) 442.50p +4.61%Moneysupermarket.com Group (MONY) 116.70p +4.29%Morgan Crucible Co (MGCR) 258.90p +4.23%Redrow (RDW) 111.90p +4.19%Taylor Wimpey (TW.) 34.84p +3.97%Bwin.party Digital Entertainment (BPTY) 132.00p +3.77%FTSE 250 - FallersOcado Group (OCDO) 104.00p -10.11%Enterprise Inns (ETI) 39.25p -3.68%Exillon Energy (EXI) 277.70p -3.68%Spirit Pub Company (SPRT) 39.75p -3.64%Debenhams (DEB) 56.80p -2.91%Ashmore Group (ASHM) 398.50p -2.80%Hansteen Holdings (HSTN) 74.35p -2.75%Misys (MSY) 250.50p -2.53%JKX Oil & Gas (JKX) 180.25p -2.44%Murray Income Trust (MUT) 598.50p -2.37%NR