The FTSE 100 was continuing to trade within an extremely tight range on Thursday morning as investors consider how much further the rally will go given that the index is already trading at levels not seen in five and a half years. Just 15 points separated the Footsie's intraday low (6,693) and high (6,708) by lunchtime as its recent winning streak is stretched into its 11th day. The FTSE 100 has been in positive territory since the start of May and was teetering around the 6,700 mark this morning, a level not seen since October 2007. The index's all-time closing high of 6,930 was recorded in December 1999, a mark which could be surpassed before the end of 2013, according to some analysts.Traders had to digest a barrage of corporate earnings in London this morning with dozens of heavyweight stocks on the FTSE 350 reporting results and trading updates. However, it was better-than-expected growth data from Japan that boosted markets early on.Japanese gross domestic product (GDP) expanded at the fastest rate in a year during the first quarter of 2013, showing that newly-appointed Prime Minister Shinzo Abe's new policies aimed at boosting growth are paying off, though this is partly because the yen has weakened substantially since aggressive monetary easing began. The Asian powerhouse registered an annualised GDP expansion of 3.5% and grew 0.9% quarter-on-quarter, beating consensus estimates of 2.8% and 0.7%, respectively.Investors yesterday chose to look on the bright side of poor GDP data from the Eurozone as it sparked hopes that the European Central Bank would look to kick-start growth in the single-currency region. Eurozone GDP shrunk by 0.2% in the first quarter, worse than the 0.1% fall expected."Traders believe that the prolonged recession leaves the ECB little choice but to look into its toolbox to employ additional stimulus measures, ranging from further rate cuts, negative deposit rates and buying asset-backed securities," said Market Strategist Ishaq Siddiqi from ETX Capital in an e-mail morning.Also supporting stocks were comments from Sir Mervyn King in the Bank of England's Quarterly Inflation Report who said that the Bank's projections are now for "stronger growth and weaker inflation" than it expected previously.FTSE 100: Aviva impresses with first-quarter updateAviva, the insurance group which surprised the market in March with an unexpected cut to its dividend, said this morning that it is delivering on its turnaround strategy, causing shares to jump early on. New business was up 18% in the first quarter, while operating expenses were down 10% and debt was reduced by £300m.Mining group Vedanta was also making gains after rewarding shareholders with a 6.0% rise in its dividend after increasing earnings and revenues in 2012. Sector peer Antofagasta however declined after saying that revenues fell 14.6% in the first quarter as the price of copper and gold dropped.Miners on the whole were leading the downside this morning with Fresnillo, EVRAZ, ENRC, Polymetal and Randgold firmly out of favour as metals prices declined.Petrofac was also in the red after saying that operations at its In Salah project in Algeria would restart in the second half following a terrorist attack in January. The company said it expects modest growth in net profits this year.Utilities group National Grid failed to excite the markets with a solid increase in full-year profits. Analysts at Societe Generale said this morning that the share-price debate is now "more focused on valuation than earnings" after a strong rise so far this year.Telecoms group Vodafone edged higher after revealed that it is to offer high-speed fixed-line broadband and internet TV services in Germany through a new collaboration with German telecoms giant Deutsche Telekom.Part-nationalised lenders RBS and Lloyds were both in demand after Prime Minister David Cameron yesterday hinted that the government would be ready to reprivatise the companies next year. Daniel Stewart upgraded both stocks to 'buy' this morning.FTSE 250: Thomas Cook jumps after cutting losses, capital restructureTravel agent Thomas Cook was flying high after cutting its half-year loss before tax from £584m to £391m and unveiling a £1.6bn plan to reorganise its capital structure.Oil firm Heritage was also a high riser after reporting that first-quarter revenues soared from just $2.3m to $236.2m due to its interest in Shoreline Natural Resources in Nigeria. FTSE 100 - RisersAviva (AV.) 346.60p +7.27%TUI Travel (TT.) 366.90p +3.24%William Hill (WMH) 447.40p +2.64%BT Group (BT.A) 319.90p +2.34%ITV (ITV) 132.20p +2.32%International Consolidated Airlines Group SA (CDI) (IAG) 274.10p +1.90%Wood Group (John) (WG.) 816.50p +1.87%Weir Group (WEIR) 2,459.00p +1.82%Lloyds Banking Group (LLOY) 60.39p +1.72%Royal Bank of Scotland Group (RBS) 312.00p +1.63%FTSE 100 - FallersFresnillo (FRES) 1,066.00p -4.82%Evraz (EVR) 151.70p -4.65%Eurasian Natural Resources Corp. (ENRC) 285.00p -4.59%Polymetal International (POLY) 630.50p -3.67%Associated British Foods (ABF) 1,986.00p -2.22%Admiral Group (ADM) 1,256.00p -2.10%Randgold Resources Ltd. (RRS) 4,700.00p -2.08%National Grid (NG.) 827.00p -2.07%Petrofac Ltd. (PFC) 1,338.00p -1.76%Rio Tinto (RIO) 2,864.00p -1.72%FTSE 250 - RisersThomas Cook Group (TCG) 162.30p +12.16%Heritage Oil (HOIL) 147.60p +10.07%TalkTalk Telecom Group (TALK) 246.50p +8.59%Dixons Retail (DXNS) 39.30p +7.64%Mitchells & Butlers (MAB) 395.30p +4.80%Oxford Instruments (OXIG) 1,580.00p +4.57%Travis Perkins (TPK) 1,549.00p +4.45%Persimmon (PSN) 1,198.00p +4.45%Imagination Technologies Group (IMG) 329.20p +3.91%Inchcape (INCH) 547.00p +3.89%FTSE 250 - FallersSynthomer (SYNT) 203.40p -9.60%African Barrick Gold (ABG) 131.50p -5.53%3i Group (III) 345.20p -5.01%Petropavlovsk (POG) 129.50p -4.36%Euromoney Institutional Investor (ERM) 990.50p -3.83%Perform Group (PER) 540.00p -3.57%Hochschild Mining (HOC) 250.30p -3.40%Kazakhmys (KAZ) 340.40p -3.27%Carpetright (CPR) 616.00p -2.92%Marston's (MARS) 148.00p -2.89%BC