Mining firm African Barrick Gold has taken a tumble after it responded to reports of a new "Super Profits Tax" on the mining industry in Tanzania, saying it is unaware of any such tax. Falling metals prices is most likely partly attributable to the fall as well.Meanwhile, Punch Taverns is a high riser, after the spell of unusually hot weather over spring had drinkers queuing up at Britain's biggest pub operator, driving a sharp rise in sales in the 12 weeks to the end of May.Rank has revealed that the 150p per share offer for the company by Malaysian investment firm Guoco Group has been declared unconditional, just a month after Rank said that the price "significantly undervalues" the group. Shares are in the red.Carillion is heading lower after revealing that its joint venture vehicle has been appointed the preferred bidder for a Canadian hospital contract, expected to be worth £390m to the contractor and support services group. Also disappointing with a contract win is defence products group Ultra Electronics, which has won contracts worth £54m with engineer Rolls-Royce to supply reactor control and instrumentation systems for Royal Navy submarines. Staffing business SThree reported a 23% increase in gross half year profit after an improved performance across all regions, helping shares higher.---BCFTSE 250 - RisersPunch Taverns (PUB) 75.10p +6.98%Misys (MSY) 390.20p +3.01%Supergroup (SGP) 1,000.00p +2.09%Moneysupermarket.com Group (MONY) 108.90p +1.49%Victrex (VCT) 1,472.00p +1.31%Afren (AFR) 166.00p +1.22%Betfair Group (BET) 803.00p +1.13%Fidelity China Special Situations (FCSS) 103.50p +1.07%Dunelm Group (DNLM) 462.90p +1.07%Kofax (KFX) 493.00p +1.02%FTSE 250 - FallersAfrican Barrick Gold (ABG) 413.10p -8.20%Cable & Wireless Worldwide (CW.) 51.10p -7.09%London & Stamford Property Ltd. (LSP) 132.20p -4.06%Cobham (COB) 214.70p -3.98%Spirax-Sarco Engineering (SPX) 1,917.00p -3.72%PZ Cussons (PZC) 373.80p -3.63%Hunting (HTG) 723.00p -3.47%Petropavlovsk (POG) 737.00p -3.34%JKX Oil & Gas (JKX) 282.90p -3.32%BBA Aviation (BBA) 208.60p -3.20%