Premier Foods unveiled industry veteran Mike Clarke as its new head honcho, which pleased the investors as shares shot up 10%. Premier Foods, which has lost about 15% of its value since the company's announcement of a profit fall, was the top flyer on the index.Clarke, currently President of Kraft Foods Europe, will take over as chief executive of Premier Foods at the beginning of September.Investment manager Ashmore Group recorded a 31% increase in assets under management in its final quarter as it saw several significant increases scored by the firm's investment "themes". Merger activity made a come back and fueled optimism among the mid-cap stocks. Charter International, the British maker of welding equipment, confirmed it is considering a £1.4bn bid from investment firm, Melrose, while Melrose said it has increased its proposed share and cash offer to 840p.In contrast, a downbeat performance recorded by Mothercare in its UK operation disappointed shareholders despite retailer's total sales rising 6.7%. Overseas growth, once again, helped a retailer offset soft domestic demand. FTSE 250 - RisersPremier Foods (PFD) 20.01p +10.55%Moneysupermarket.com Group (MONY) 113.50p +6.67%Hochschild Mining (HOC) 501.00p +5.70%ITE Group (ITE) 227.70p +5.47%Petropavlovsk (POG) 839.50p +5.33%Ashmore Group (ASHM) 410.60p +4.29%International Personal Finance (IPF) 377.30p +3.37%Spectris (SXS) 1,689.00p +3.11%Pace (PIC) 113.80p +3.08%Morgan Crucible Co (MGCR) 365.20p +2.64%FTSE 250 - FallersThomas Cook Group (TCG) 76.00p -10.01%Barratt Developments (BDEV) 105.00p -5.58%Daily Mail and General Trust (DMGT) 421.00p -4.19%Betfair Group (BET) 677.50p -4.04%Euromoney Institutional Investor (ERM) 604.50p -3.43%Cable & Wireless Worldwide (CW.) 47.04p -3.43%National Express Group (NEX) 241.60p -3.36%William Hill (WMH) 216.80p -3.34%Mitchells & Butlers (MAB) 297.30p -2.72%Imagination Technologies Group (IMG) 389.00p -2.70%