It was a choppy session on Tuesday with the FTSE 100 struggling for direction early on before sinking firmly into the red as concerns of a 'tapering' of stimulus in the US dampened sentiment.The FTSE 100 finished down 15 points at 6,604, though closed well off its intraday low after a late rally. The heavyweight mining sector was providing a big drag on London's benchmark index today as metals prices weakened. Putting pressure on commodity prices was a strengthening dollar on the back of rising bets that the Federal Reserve will soon begin to scale back its quantitative easing (QE) programme, a stimulus measure that has a dilutive effect on the greenback.The President of the Atlanta Fed, Dennis Lockhart, said today that the central bank could start tapering QE at any of the three remaining policy meetings this year (ie as early as September). Meanwhile, Dallas Fed's Richard Fisher said yesterday that the Fed is "now closer to execution mode" after last week's fall in the unemployment rate.More weight was thrown behind the argument for tapering today after the trade deficit narrowed much more than expected in June, prompting economists to revise up their growth forecasts for the second quarter."Tuesday is the second day of data pointing to a resurging economy, putting to bed some of those hopes by liquidity-loving investors that last Friday's non-farm payrolls report is disappointing enough for the Fed to hold back on reducing stimulus," said Market Strategist Ishaq Siddiqi from ETX Capital.Providing some support to UK markets this morning were strong domestic industrial production figures: data showed a 1.1% month-on-month increase in industrial output, well ahead of the consensus forecast for a 0.6% rise.FTSE 100: Fresnillo leads miners lowerFalls in commodity prices across the board were weighing on share prices in the mining sector on Tuesday, with precious metals group Fresnillo leading the way lower after a poorly-received first-half report. Fresnillo's share price finished down nearly 11% after a 27% decline in gross profit to $518.9m in the first half as revenues dropped on falling gold and silver prices during the period.FTSE 100 mining peers Randgold, Vedanta, Antofagasta, Glencore Xstrata, Anglo American and Rio Tinto were all registering moderate falls today.Leading the upside was hotels group InterContinental which impressed with a $350m special dividend as it reported that revenue per available room rose 3.7% in the first half.Emerging markets-focused bank Standard Chartered also rose strongly after posting a 4.0% rise in adjusted first-half profits to $4.09bn and lifting its interim dividend by 6.0%.Financial services organisation Legal & General was also higher after its first-half results saw double-digit growth in sales, cash generation and profits.Quality control and testing firm Intertek wasn't far behind after RBC Capital Markets upgraded its recommendation to 'sector performer' and hiked its target price from 2,850p to 3,050p.In contrast, broker downgrades were dampening the share prices of a number of heavyweight stocks: consumer products group Unilever was lower after JPMorgan Cazenove downgraded the stock to 'neutral'; GlaxoSmithKline was down after Citigroup reduced its rating to 'neutral'; meanwhile banking group HSBC was extending losses made yesterday after disappointing with its interim report as Deutsche Bank lowering its rating to 'hold'.FTSE 250: esure plummets on gloomy guidance In its debut results since its flotation in March, insurer esure revealed that a robust rise in first-half premiums was unlikely to be repeated in the second half of the year, causing the stock to sink well below its initial public offering price.The share price of Greggs also fell heavily after the bakery chain reported lower-than-forecast results with a 28.8% drop in pre-tax profit in the first half.Meanwhile, first-half results from industrial valve manufacturer Rotork gave the stock a boost after the firm reported record revenues and profits across each division.FTSE 100 - RisersInterContinental Hotels Group (IHG) 2,030.00p +6.39%Standard Chartered (STAN) 1,567.50p +2.85%TUI Travel (TT.) 401.50p +2.42%Wolseley (WOS) 3,315.00p +2.41%Intertek Group (ITRK) 3,158.00p +2.37%Legal & General Group (LGEN) 201.90p +2.28%ARM Holdings (ARM) 886.50p +1.66%Diageo (DGE) 2,136.50p +1.47%Aberdeen Asset Management (ADN) 385.00p +1.37%BG Group (BG.) 1,209.50p +1.17%FTSE 100 - FallersFresnillo (FRES) 924.50p -10.85%Vedanta Resources (VED) 1,170.00p -5.65%Randgold Resources Ltd. (RRS) 4,428.00p -5.55%Antofagasta (ANTO) 849.50p -4.92%Glencore Xstrata (GLEN) 275.65p -4.82%Admiral Group (ADM) 1,268.00p -4.66%Anglo American (AAL) 1,416.00p -4.03%Meggitt (MGGT) 544.00p -1.89%Lloyds Banking Group (LLOY) 74.26p -1.89%Eurasian Natural Resources Corp. (ENRC) 221.10p -1.69%FTSE 250 - RisersRotork (ROR) 2,912.00p +7.69%Salamander Energy (SMDR) 123.00p +4.06%Electrocomponents (ECM) 261.00p +3.74%Savills (SVS) 664.50p +3.50%Daejan Holdings (DJAN) 4,030.00p +2.75%Crest Nicholson Holdings (CRST) 349.20p +2.52%Fenner (FENR) 350.80p +2.36%Monks Inv Trust (MNKS) 376.50p +2.31%Restaurant Group (RTN) 555.50p +2.11%Big Yellow Group (BYG) 437.00p +1.98%FTSE 250 - Fallersesure Group (ESUR) 246.00p -21.03%Greggs (GRG) 402.30p -8.90%Spirent Communications (SPT) 141.50p -8.53%Kazakhmys (KAZ) 247.00p -7.04%Ferrexpo (FXPO) 163.40p -6.47%Vesuvius (VSVS) 452.00p -4.84%Bumi (BUMI) 214.40p -4.71%Polymetal International (POLY) 637.00p -4.57%Evraz (EVR) 93.00p -4.37%African Barrick Gold (ABG) 111.60p -3.96%BC