Bluetooth chip specialist CSR advanced after saying it is using its cash pile of more than $400m (£260m) to buy back as much as $50m (£32m) of shares.Bosses said they are "very confident" in the company's investment case and ability to generate shareholder value.On the downside, Centamin Egypt fell sharply after revising down 2010 gold production estimates, but Ambrian thinks all the problems are only short term, so keeps its 'buy' stance.FTSE 250 - RisersCSR (CSR) 350.70p +11.05%Supergroup (SGP) 1,149.00p +6.78%Ashtead Group (AHT) 99.00p +4.93%PZ Cussons (PZC) 345.00p +4.83%Keller Group (KLR) 644.50p +4.29%Telecity Group (TCY) 527.50p +4.15%De La Rue (DLAR) 695.50p +3.96%Aquarius Platinum Ltd. (AQP) 329.00p +3.82%BlueBay Asset Management (BBAY) 321.10p +3.68%Wellstream Holdings (WSM) 588.00p +3.61%FTSE 250 - FallersHansen Transmissions International (HSN) 53.00p -10.17%Centamin Egypt (CEY) 168.80p -8.31%Laird (LRD) 133.10p -3.20%Xchanging (XCH) 129.50p -2.63%Spectris (SXS) 999.50p -1.91%Dairy Crest Group (DCG) 378.40p -1.69%Gartmore Group (GRT) 118.50p -1.58%Salamander Energy (SMDR) 242.00p -1.47%Melrose Resources (MRS) 290.00p -1.36%Mitie Group (MTO) 199.80p -1.33%