It was hard going for the leading index Thursday, with gains among some of the more unfashionable blue chip names just about cancelling losses at BP and heavyweight miners.The FTSE 100 struck a new 2½-year intraday high early in the session, but that was as good as it got, and only a sudden improvement on Wall Street dragged London close to breakeven late on.Oil giant BP was a major drag following news that the US government is to sue the company over the Gulf of Mexico oil spill. It filed a civil lawsuit against BP and eight other companies over the Deepwater Horizon oil rig explosion that killed 11 workers and the subsequent oil spill in the Gulf of Mexico. It traded as low as 461p at one point - a 3% drop - but recovered through the day to end just 6 pence adrift.Miners were also off colour as metal prices fell. Copper giant Antofagasta was worst hit, though Fresnillo and African Barrick Gold weren't far behind.Back to the oil sector and BG Group continued its purple patch, announcing its second discovery in as many days, this time in the Santos Basin, offshore Brazil, where the eleventh well on the BM-S-11 concession struck oil. An upbeat trading update from Serco took the outsourcing giant to the top of the pile. It expects strong organic revenue growth this year. The group, which is a big outsourcer to the public sector, reiterated previous guidance of an increase in revenue to around £5bn and a rise in adjusted operating profit margin to about 6.3% by the end of 2012. That hauled rival Capita higher. Financial Times publisher Pearson also did well. It continues to benefit from yesterday's Deutsche Bank upgrade to 'buy' with 1,020p target price. Among the mid-caps, Sports Direct is in demand after it posted a sharp rise in profits in the half year to 24 October as the football World Cup and strong growth in internet shopping boosted sales, but the sports shop chain is anticipating a tough start to the new year. Underlying pre-tax profits were up to £100.7m, from £71.9m the previous year on revenues that climbed to £819.9m from £756.9m. "The group has continued to perform strongly during the first eight months of this financial year," said boss Dave Forsey.Financial software provider Misys was also wanted after saying it will buy back £525m of shares at 310p each via its tender offer, with the remaining £145m dished out by way of a pro rata return of capital to all shareholders. The company committed to handing back £670m to investors following the sale of a big stake in healthcare division Allscripts earlier this year. It still owns 10%. Real estate company Segro, formerly Slough Estates, has shifted finance director David Sleath into the hot seat to replace Ian Coull who retires after the AGM in April. Sleath, 49, has been the company's chief number cruncher since 1 January 2006, and his switch triggers a hunt for a new FD. Five-a-side football pitch operator Goals Soccer has seen resilient trading recently though the recent snowfall will have an impact of about £0.7m on pre-tax profits for the year to 31 December.FTSE 100 - RisersSerco Group (SRP) 597.00p +4.10%GKN (GKN) 213.80p +3.04%Pearson (PSON) 1,024.00p +1.89%Capita Group (CPI) 690.00p +1.85%Marks & Spencer Group (MKS) 382.00p +1.79%3i Group (III) 323.30p +1.51%Whitbread (WTB) 1,800.00p +1.47%Burberry Group (BRBY) 1,141.00p +1.42%Bunzl (BNZL) 722.00p +1.33%Associated British Foods (ABF) 1,139.00p +1.24%FTSE 100 - FallersAntofagasta (ANTO) 1,528.00p -2.05%Fresnillo (FRES) 1,525.00p -1.93%Weir Group (WEIR) 1,770.00p -1.72%Schroders (Non-Voting) (SDRC) 1,387.00p -1.63%Man Group (EMG) 287.50p -1.61%Royal Bank of Scotland Group (RBS) 40.12p -1.57%BP (BP.) 470.00p -1.37%African Barrick Gold (ABG) 593.50p -1.33%BT Group (BT.A) 179.40p -1.32%Intertek Group (ITRK) 1,861.00p -1.22%FTSE 250 - RisersAshtead Group (AHT) 166.10p +5.59%Yule Catto & Co (YULC) 315.00p +3.28%Sports Direct International (SPD) 150.50p +3.08%Domino Printing Sciences (DNO) 586.00p +2.81%Charter International (CHTR) 797.50p +2.77%Taylor Wimpey (TW.) 28.05p +2.63%F&C Commercial Property Trust Ltd. (FCPT) 101.40p +2.42%Laird (LRD) 164.60p +2.36%Premier Farnell (PFL) 285.80p +2.07%Go-Ahead Group (GOG) 1,304.00p +2.03%FTSE 250 - FallersPartyGaming (PRTY) 218.00p -5.63%Grainger (GRI) 104.00p -4.59%Petropavlovsk (POG) 1,089.00p -4.22%Avis Europe (AVE) 210.70p -4.05%Mondi (MNDI) 475.70p -3.84%International Personal Finance (IPF) 350.20p -3.47%Xchanging (XCH) 102.70p -3.20%Dunelm Group (DNLM) 532.50p -3.18%Aquarius Platinum Ltd. (AQP) 338.00p -2.65%BlackRock World Mining Trust (BRWM) 770.50p -2.59%