Oil group Tullow was among the worst performers on Monday after saying it has plugged and abandoned its Tultule-1 wildcat well onshore Ethiopia as it failed to encounter oil. Mining stocks were also under heavy selling pressure despite data showing a strong acceleration in export growth last month. "Of course for the miners, the concern is imports not exports, and while import growth continues to lag the demand outlook for the sector weakens," said Toby Morris, Senior Sales Trader at CMC Markets. India-focused miner Vedanta was a heavy faller today ahead of its potential departure from the FTSE 100 next week. The quarterly reshuffle of the index is expected to see the stock replaced by newly-listed Royal Mail.Other miners, including Fresnillo, Antofagasta, Randgold Resources and Rio Tinto, were also registering losses despite widespread increases of metals prices today.Airline group IAG was flying higher on reports that subsidiary British Airways is looking to block changes to its APS pension scheme that could lead to increased payments to its retired employees. Market chatter suggests that increased pension payouts could affect when IAG begins to pay dividends.Insurance group Aviva was on the up after analysts at Bank of America Merrill Lynch raised their target price for the stock and added the name to their top European picks list.Sector peer Admiral was also in demand after the announcement that it has extended its underwriting agreement with Munich Re. Analyst Nick Johnson from Numis Securities said the extension should also ease fears that Admiral might need to reduce its dividend to increase regulatory capital "if the company encountered reduced reinsurer support".FTSE 100 - RisersInternational Consolidated Airlines Group SA (CDI) (IAG) 365.00p +2.07%Shire Plc (SHP) 2,752.00p +1.59%Aviva (AV.) 425.40p +1.43%Vodafone Group (VOD) 233.80p +1.28%Weir Group (WEIR) 2,071.00p +0.93%Hargreaves Lansdown (HL.) 1,219.00p +0.83%Capita (CPI) 996.50p +0.66%Rolls-Royce Holdings (RR.) 1,202.00p +0.59%TUI Travel (TT.) 380.30p +0.58%Meggitt (MGGT) 498.30p +0.57%FTSE 100 - FallersTullow Oil (TLW) 870.00p -3.28%Vedanta Resources (VED) 826.00p -2.19%Marks & Spencer Group (MKS) 461.20p -2.02%Petrofac Ltd. (PFC) 1,171.00p -1.93%Fresnillo (FRES) 742.50p -1.92%Antofagasta (ANTO) 758.00p -1.43%Aggreko (AGK) 1,602.00p -1.29%William Hill (WMH) 374.80p -1.24%Randgold Resources Ltd. (RRS) 3,991.00p -1.19%Rio Tinto (RIO) 3,272.00p -1.00%BC