The FTSE 100 opened broadly flat on Friday morning as traders became nervous ahead of a fourth-quarter reading of UK gross domestic product (GDP) growth in the UK."European markets opened cautiously today as a lack of corporate data due today provided bulls with an excuse to take profits amidst some markets which have recently hit four-and-a-half year highs," said financial trader Shavaz Dhalla from Spreadex. "Many markets are still only trading slightly south from yesterday's close. Thus, even in the face of mixed corporate data, economic problems with some Eurozone nations as well as continuing debt problems in the US, investors still believe that there could be value for money within the stock markets."London's benchmark index surged by over one per cent on Thursday following some better-than-expected manufacturing data from China and the US, and an improved composite purchasing managers' index in the Eurozone.Today, however, the focus will be on the UK fourth-quarter GDP reading due out at 09:30. Consensus forecasts are for a 0.1% quarter-on-quarter contraction in the UK economy in the fourth quarter of 2012, compared with the 0.9% growth seen in the third.FTSE 100: IAG, Polymetal flying high after upgradesAirline IAG was a high riser this morning after JPMorgan Cazenove raised its rating for the stock to 'overweight'. Meanwhile, Polymetal gained after UBS upgraded its recommendation from to 'buy' and hiked its price target by 11%. The broker said: "We think that now is the right moment to use weakness in the stock price as potential merger with Polyus Gold may be a strong driver.Diversified miner Anglo American edged higher despite admitting that strikes held back production of platinum and iron ore in the fourth quarter. Nevertheless, most other commodity classes delivered 'solid' increases in output. Xstrata was also up after saying that the definitive estimate for the Las Bambas project in southern Peru is $5.2bn.Other miners however slipped into the red, with EVRAZ, Rio Tinto and BHP Billiton among the worst performers early on.FTSE 250: easyJet lifted by UBS upgradeShares in budget airline easyJet were higher after UBS raised its rating to 'buy' after yesterday's better-than-expected first-quarter results. The broker said that growth is gaining momentum with the company "becoming more positive on 1H performance".Telecoms group Cable & Wireless Comms was lower after HSBC cut its rating to 'neutral'.FTSE 100 - RisersInternational Consolidated Airlines Group SA (CDI) (IAG) 225.00p +3.02%Polymetal International (POLY) 1,107.00p +1.56%Sage Group (SGE) 322.90p +1.51%Aberdeen Asset Management (ADN) 411.10p +1.38%TUI Travel (TT.) 285.60p +1.28%United Utilities Group (UU.) 756.50p +1.20%Reckitt Benckiser Group (RB.) 4,157.00p +0.97%BT Group (BT.A) 251.60p +0.96%Marks & Spencer Group (MKS) 383.00p +0.87%Imperial Tobacco Group (IMT) 2,410.00p +0.84%FTSE 100 - FallersEvraz (EVR) 302.50p -1.43%BP (BP.) 462.50p -1.11%Eurasian Natural Resources Corp. (ENRC) 336.30p -0.85%BAE Systems (BA.) 339.90p -0.85%BHP Billiton (BLT) 2,120.50p -0.84%Hargreaves Lansdown (HL.) 719.50p -0.83%BG Group (BG.) 1,162.50p -0.73%Lloyds Banking Group (LLOY) 53.17p -0.58%Randgold Resources Ltd. (RRS) 6,130.00p -0.57%Rio Tinto (RIO) 3,555.50p -0.55%FTSE 250 - RiserseasyJet (EZJ) 928.00p +3.28%United Drug (UDG) 272.80p +2.94%Enterprise Inns (ETI) 97.15p +2.26%Afren (AFR) 154.00p +1.72%Premier Farnell (PFL) 212.60p +1.72%Alent (ALNT) 336.50p +1.66%Debenhams (DEB) 106.20p +1.63%Inmarsat (ISAT) 619.50p +1.56%Ladbrokes (LAD) 209.20p +1.50%Barratt Developments (BDEV) 225.90p +1.44%FTSE 250 - FallersITE Group (ITE) 267.00p -2.34%London & Stamford Property (LSP) 114.50p -2.22%Petropavlovsk (POG) 381.20p -2.03%SIG (SHI) 132.00p -1.93%Hochschild Mining (HOC) 431.70p -1.57%Rank Group (RNK) 150.50p -1.31%BH Macro Ltd. EUR Shares (BHME) € 19.60 -1.26%F&C Asset Management (FCAM) 108.40p -1.09%Chemring Group (CHG) 293.70p -1.08%Victrex (VCT) 1,603.00p -1.05%BC