A host of FTSE 100 heavyweights disappointed with earnings reports on Thursday morning, as market sentiment was still fragile after yesterday's shock economic contraction in the States.The world's largest economy shrank by 0.1% in the last three months of last year, a stark contrast to the 3.1% growth seen in the third quarter. Forecasts were for a 1.1% expansion."A weak reading for Q4 GDP in the US yesterday afternoon tempered demand for risk assets and capped gains in equity indices short term," said Matt Basi, a senior sales trader at CMC Markets.Meanwhile, the Federal Open Market Committee said last night in its January statement that it would keep rates unchanged and continue to purchase securities at a rate of $85bn-a-month. The Fed said "with appropriate policy accommodation, economic growth will proceed at a moderate pace". Policy-makers also expect the jobless rate to "gradually decline" towards levels constant with its mandate.The focus now turns to jobless claims and personal income data this afternoon in the US. Nevertheless, the big event of the week will be tomorrow's January jobs report given the disappointing growth figures for the fourth quarter.FTSE 100: Big hitters disappointPharmaceutical titan AstraZeneca dropped after reporting that full-year revenue fell 15% due to a loss of exclusivity on several brands. The company also said that it would not buy back any shares in 2013 "in order to maintain the flexibility to invest the business". Oil giant Royal Dutch Shell was lower after full-year profits slipped slightly as a result of oil price volatility. An analyst at Investec labelled the company's fourth quarter as a "substantial miss".Consumer goods giant Diageo was higher after posting profits broadly in line with market expectations. While North American growth was weaker-than-expected and Europe saw continued weakness, this was offset by a strong performance in the Emerging Markets. A third-quarter production report from Vedanta disappointed early on but shares had pulled into positive territory by lunchtime. The company said that oil and gas output rose 21% and mined metal and silver increased strongly.Leading the risers Kazakh copper-focused miner Kazakhmys was flat after saying it had hit production targets across all asset classes in 2012.Broadcaster and broadband group BSkyB gained after beating profit forecasts in the first half, helped by a surge in customer numbers. The firm also hiked its dividend by a fifth.Engineering firm Babcock edged higher after saying it has traded well in first half and is confident of meeting expectations for the full year.Utilities group SSE rose after saying that it is on course to deliver increases in both adjusted profits and its dividend this year despite a slight fall in the number of customer accounts during the first nine months.FTSE 250: Lonmin, M&B surgeLonmin, the world's third largest platinum producer, jumped after posting quarterly production ahead of targets despite strikes that hit the South African mining sector last year.Robust festive trading figures for pubs group Mitchells & Butlers saw shares advance this morning; the company reported a 1.0% increase in like-for-like sales in the 14 weeks to January 5th.Sector peer Enterprise Inns suffered heavy falls after Numis downgraded its rating on the stock this morning.FTSE 100 - RisersDiageo (DGE) 1,888.50p +1.92%CRH (CRH) 1,371.00p +1.86%British Sky Broadcasting Group (BSY) 822.00p +1.48%Petrofac Ltd. (PFC) 1,636.00p +1.30%Rolls-Royce Holdings (RR.) 953.50p +1.17%Pearson (PSON) 1,205.00p +1.09%BHP Billiton (BLT) 2,170.00p +0.98%Babcock International Group (BAB) 1,041.00p +0.87%Vedanta Resources (VED) 1,174.00p +0.86%ITV (ITV) 114.60p +0.79%FTSE 100 - FallersAstraZeneca (AZN) 2,984.00p -5.34%Evraz (EVR) 282.00p -3.16%Royal Bank of Scotland Group (RBS) 338.90p -2.39%Sage Group (SGE) 325.20p -1.93%Royal Dutch Shell 'A' (RDSA) 2,264.50p -1.78%Admiral Group (ADM) 1,219.00p -1.53%Barclays (BARC) 297.55p -1.47%Prudential (PRU) 959.00p -1.44%Royal Dutch Shell 'B' (RDSB) 2,328.50p -1.42%Marks & Spencer Group (MKS) 377.70p -1.41%FTSE 250 - RisersLonmin (LMI) 345.60p +9.71%Mitchells & Butlers (MAB) 321.90p +8.75%Imagination Technologies Group (IMG) 516.00p +3.64%BTG (BTG) 330.60p +3.15%JD Sports Fashion (JD.) 754.50p +2.72%Great Portland Estates (GPOR) 483.60p +2.28%Supergroup (SGP) 604.50p +2.28%Renishaw (RSW) 1,900.00p +2.15%Barr (A.G.) (BAG) 537.00p +2.09%ITE Group (ITE) 258.30p +1.89%FTSE 250 - FallersEnterprise Inns (ETI) 89.55p -9.27%New World Resources A Shares (NWR) 277.80p -4.54%Brewin Dolphin Holdings (BRW) 207.60p -3.22%3i Group (III) 265.30p -2.64%Redrow (RDW) 187.20p -2.40%Home Retail Group (HOME) 119.70p -2.37%Investec (INVP) 459.10p -2.30%Man Group (EMG) 87.85p -2.17%Laird (LRD) 222.70p -2.11%AZ Electronic Materials SA (DI) (AZEM) 372.20p -1.98%BC