Tullow Oil was among the worst performers after the firm said that while it has discovered hydrocarbons at an exploration well offshore Sierra Leone, the area where it has found oil "is likely to require additional evaluation". While Tullow's Exploration Director Angus McCoss says the results are "encouraging", many analysts have pointed to the fact that the well will need further appraisal due to the limited information given - a possible reason for the negative market reaction this morning. Sector peers Essar Energy, Cairn Energy, BG Group, Petrofac and Shell were also weighing the index down, pulling back following a strong performance yesterday.Meanwhile, interdealer broker ICAP was in demand after acquiring Singaporean shipbroking company Island Shipbrokers for an undisclosed sum, a move which the firm believes will complement its existing operations and strengthen ICAP Shipping's growth in Asia. Miners were also on the rise as they tracked metal prices higher. Vedanta Resources and Anglo American were both making strong gains. FTSE 100 - RisersVedanta Resources (VED) 1,419.00p +4.49%Admiral Group (ADM) 1,038.00p +2.67%Kazakhmys (KAZ) 1,162.00p +1.31%ICAP (IAP) 394.20p +1.18%GlaxoSmithKline (GSK) 1,421.50p +1.03%Anglo American (AAL) 2,716.50p +0.99%Rolls-Royce Holdings (RR.) 800.50p +0.95%Johnson Matthey (JMAT) 2,363.00p +0.51%Associated British Foods (ABF) 1,225.00p +0.49%British American Tobacco (BATS) 3,128.00p +0.47%FTSE 100 - FallersTullow Oil (TLW) 1,537.00p -4.00%Evraz (EVR) 416.30p -3.72%International Consolidated Airlines Group SA (IAG) 168.80p -2.65%Essar Energy (ESSR) 122.30p -2.24%Land Securities Group (LAND) 676.50p -2.17%Barclays (BARC) 245.50p -2.15%Hammerson (HMSO) 393.20p -2.12%Capita (CPI) 643.50p -1.98%Smiths Group (SMIN) 1,039.00p -1.98%Carnival (CCL) 1,942.00p -1.97%NR