Mining stocks were performing well after Citigroup lifted its stance on the sector from 'neutral' to 'bullish', representing its first positive outlook for the industry in three years. The bank has labelled BHP Billiton, Rio Tinto and Glencore Xstrata as its "key picks" as it said that sentiment will begin to improve in the sector after having hit "rock bottom".Tullow Oil shares climbed after the Financial Times's Lex Column said the stock should be a play for investors despite a 50% fall in the explorer and producer's shares over the last two years. Centrica shares recovered from yesterday's hit, which came on the back of a downgrade from Barclays to 'underweight'. United Utilities was lifted by an upgrade from Morgan Stanley to 'overweight'.Meanwhile, Associated British Foods fell after it posted a mixed first quarter. The food ingredients company said that the profit decline in its Sugar division will be "greater than previously expected" due to a reduction in sugar prices, but higher-than-estimated margins at Primark should help make up the difference. Intertek fell after Berenberg cut the stock to 'hold'.Sports Direct International fell after revealing it has sold the 4.6% stake it bought in fellow retailer Debenhams on Monday and replaced it with a put option over a larger shareholding. Today the group said the stake had been sold, with a put option agreement taken out instead over a larger 6.6% stake in FTSE 250-listed Debenhams. Royal Mail was pushed lower by a downgrade from Beaufort Securities to 'hold'.FTSE 100 - RisersAntofagasta (ANTO) 827.00p +4.68%Anglo American (AAL) 1,392.00p +4.47%Fresnillo (FRES) 726.00p +4.31%BHP Billiton (BLT) 1,863.00p +3.99%Tullow Oil (TLW) 897.00p +3.94%United Utilities Group (UU.) 684.50p +3.87%Rio Tinto (RIO) 3,379.00p +3.84%Glencore Xstrata (GLEN) 331.05p +3.63%Randgold Resources Ltd. (RRS) 3,881.00p +2.40%Centrica (CNA) 321.10p +1.77%FTSE 100 - FallersAssociated British Foods (ABF) 2,575.00p -4.49%Intertek Group (ITRK) 2,894.00p -2.85%Sports Direct International (SPD) 721.00p -2.17%British Sky Broadcasting Group (BSY) 851.00p -2.13%Prudential (PRU) 1,348.00p -2.11%ARM Holdings (ARM) 987.00p -1.99%Lloyds Banking Group (LLOY) 84.59p -1.98%Amec (AMEC) 1,033.00p -1.81%Travis Perkins (TPK) 1,853.00p -1.75%Royal Mail (RMG) 605.00p -1.63%NR