Titanium miner Kenmare Resources was leading the risers today, extending its strong run as bid speculation continues to circulate. The stock is now up over 20% over the last month, with the Financial Times reporting last week that Rio Tinto or a Chinese firm could be eyeing the firm as a takeover target. According to this morning's Questor column in the Telegraph, any bid from Rio is unlikely to bear fruit on competition grounds, given that the FTSE 100 miner "already accounts for about a quarter of the global market for titanium dioxide." Nevertheless, the paper says that despite bid talks looking wide of the mark, the business has an excellent growth plan already - "Kenmare is a buy without a bid", writes Garry White.Russia-focused gold miner Petropavlovsk was higher after Nomura upgraded its rating from reduce to neutral, saying that group's resource update this week could provide positive news on the production potential of its Pioneer mine. Rising gold prices were also helping lift the stock higher as well.Croda International, the speciality chemical producer, was also a high riser after achieving a profit before tax of £60m in the final quarter of 2011, a rise of 22.7% compared to the same period of 2010. For the full year, the company saw pre-tax profits rise 25.9% against 2010, hitting £242.2m by the end of December. Meanwhile, sausage skin maker Devro was falling despite seeing profit before tax and exceptionals rise 22.4% from £35.2m to £43m. Reuters has today highlighted the recent strong share price performance prior to the results and concerns over increasing energy and raw materials costs. FTSE 250 - RisersKenmare Resources (KMR) 60.10p +6.56%Petropavlovsk (POG) 726.00p +4.24%Croda International (CRDA) 2,089.00p +2.86%Domino Printing Sciences (DNO) 658.50p +2.57%Misys (MSY) 338.50p +2.54%Dunelm Group (DNLM) 518.50p +2.17%Booker Group (BOK) 75.50p +1.62%JD Wetherspoon (JDW) 410.00p +1.26%COLT Group SA (COLT) 96.20p +1.26%Go-Ahead Group (GOG) 1,335.00p +1.21%FTSE 250 - FallersCSR (CSR) 257.00p -6.55%Devro (DVO) 277.00p -5.78%Kesa Electricals (KESA) 81.35p -5.08%Homeserve (HSV) 222.80p -4.95%Cable & Wireless Worldwide (CW.) 26.62p -4.31%Home Retail Group (HOME) 109.00p -3.80%Big Yellow Group (BYG) 289.80p -3.62%Rentokil Initial (RTO) 78.10p -2.98%Computacenter (CCC) 401.70p -2.92%RPC Group (RPC) 380.00p -2.79%NR/BC