The FTSE 100's losses have grown with miners on the back foot amid worries over global growth.Silver specialist Fresnillo leads the mining sector lower in the FTSE 100. Worries that China may further tighten monetary policy are hurting commodity prices. Lower oil prices were evident on the markets, with airlines such as the budget carrier easyJet, which earlier this week said high fuel prices leave it cautious, bucking the downward trend.In company news, Telecoms giant BT saw underlying profit before tax surge 21% in the final quarter of its financial year (Q1 2011) from a year earlier, despite revenue easing 6% year on year. The full year dividend has been hiked 7% to 7.4p. But the stock is one of the poorest performers in the FTSE 100 today.Oil and gas firm Tullow is another struggler today, even after it said it has performed very strongly so far in 2011, with "excellent results" from its drilling programme in Ghana, while significant progress has been made in Uganda. Life assurance sales at insurance giant Old Mutual fell by 4% in the first quarter, primarily as a result of tough comparators in its Italian division. The shares are lower. Sales on an annual premium equivalent (APE) basis fell by 4% (constant currency) to £369m, from £386m in the first three months of 2010But the FTSE 250 that is seeing the biggest falls. Fast-growing fashion group SuperGroup failed to get its summer range out in time for the unseasonably warm weather seen recently, resulting in a lower sales growth rate in the three months to 1 May. The company, best known for the Superdry label, said total sales were up by 61% from the same period a year ago at £66m. The fourth quarter growth rate was lower than the 71% rise seen in the full year to 1 May, during which retail and wholesale sales climbed by 71%.A profit warning from Keller has the ground engineering specialist posting double-digit percentage losses. The group warned that the impact of lower margins in the US, combined with the Australian floods and geopolitical issues in the Middle East and North Africa, mean it now expects group's EBIT for the year to be around 10% below that in 2010, with the second half being broadly in line with last year.Dixons Retail has maintained its profit forecast for the year to 30 April, despite continued tough trading at the PC World and Curry's owner. In March, the firm said underlying pre-tax profits for the year would be about £85m, having previously indicated they would be above £100m. The latest forecast has been maintained, despite second half sales falling by 4% from the same period a year ago, against a 2% decline over the full year. RSA Insurance hailed a strong start to the year with net written premiums of £2.1bn in the first quarter, up 8% on a year earlier. All regions delivered good growth. The group remains confident of delivering full year premium growth of around 10% in International, targeted growth in the UK and double digit growth in emerging markets.Levels of client advertising and research expenditure have picked up in 2011 and Aegis Group, which is bucking the downward trend today expects this trend to continue for the rest of the year. The media buying and market research agency expects organic revenue growth for 2011 to be at least in line with the level achieved last year "in spite of the more difficult comparatives for the remainder of the year." 3i leads the risers in the FTSE 100. The private equity group said investment increased to £719 million in the year to 31 March, up from £386m in 2010.Also in the FTSE 100, mining group Eurasian Natural Resources Corporation (ENRC) has reported a positive first quarter, driven by strong production and sales volumes and high commodity prices. However, it warned it faced cost pressures as prices for a number of key input materials continued to increase faster than expected.Specialist business publisher and trade events group Informa is among the FTSE 250-listed stocks bucking the downward trend today after saying it is on track for the full year, after first quarter revenues grew by 4.6%, helped by strong growth in Events and Training, and a better-than-expected performance in Academic Information. So too is Hikma Pharmaceuticals, which said it was on track to hit growth forecasts, with its operations businesses in Egypt, Tunisia and Bahrain performing well despite recent unrest. The Jordan-based firm said it was very pleased with the speed at which operations in these countries were returning to normal, although sales activities in Libya and Yemen remain limited.FTSE 100 - Risers3i Group (III) 293.90p +8.17%Centrica (CNA) 317.20p +1.76%Scottish & Southern Energy (SSE) 1,372.00p +1.55%International Consolidated Airlines Group SA (IAG) 249.40p +1.22%AstraZeneca (AZN) 3,173.50p +0.99%Carnival (CCL) 2,612.00p +0.85%ITV (ITV) 72.50p +0.83%Pearson (PSON) 1,166.00p +0.78%GlaxoSmithKline (GSK) 1,318.50p +0.69%Royal Bank of Scotland Group (RBS) 42.71p +0.68%FTSE 100 - FallersFresnillo (FRES) 1,333.00p -5.53%Man Group (EMG) 241.60p -4.39%Kazakhmys (KAZ) 1,211.00p -4.27%ICAP (IAP) 489.50p -3.93%Old Mutual (OML) 130.40p -3.62%Eurasian Natural Resources Corp. (ENRC) 832.00p -3.48%Antofagasta (ANTO) 1,148.00p -3.45%Lonmin (LMI) 1,500.00p -3.29%Vedanta Resources (VED) 2,098.00p -3.09%Johnson Matthey (JMAT) 1,957.00p -3.07%FTSE 250 - RiserseasyJet (EZJ) 367.40p +2.88%FirstGroup (FGP) 361.00p +2.62%Misys (MSY) 360.30p +2.27%Rentokil Initial (RTO) 97.20p +2.05%National Express Group (NEX) 268.10p +1.94%Hikma Pharmaceuticals (HIK) 823.50p +1.92%Northumbrian Water Group (NWG) 362.30p +1.48%Halma (HLMA) 386.60p +1.34%Carillion (CLLN) 402.80p +1.26%Informa (INF) 431.60p +1.22%FTSE 250 - FallersKeller Group (KLR) 528.00p -20.12%Supergroup (SGP) 1,263.00p -19.76%Tullett Prebon (TLPR) 394.60p -5.49%Elementis (ELM) 152.90p -4.38%Heritage Oil (HOIL) 228.00p -4.08%Kenmare Resources (KMR) 43.75p -3.95%Petropavlovsk (POG) 815.00p -3.95%Ferrexpo (FXPO) 455.90p -3.80%Gem Diamonds Ltd. (DI) (GEMD) 272.40p -3.40%Aquarius Platinum Ltd. (AQP) 331.40p -3.38%