The FTSE 100 was making meagre gains on Thursday morning as sentiment remained fragile following the sell-off the day before, with investors taking caution ahead of some key economic indicators.Global economic concerns sent London's top-tier index down 2.0% on Wednesday after the OECD slashed its worldwide growth estimates and the International Monetary Fund reduced its forecasts for China. Meanwhile, volatile trading in Japan endured overnight with the benchmark Nikkei index dropping over 5.0% as the yen continued to strengthen against the dollar.Increased speculation that the Federal Reserve will soon begin to scale back its quantitative easing (QE) programme - stimulus has been a big boost to equity markets since the start of the year - has weighed heavily on stocks over recent days. The steadily improving nature of US economic data over recent weeks has thrown more weight behind the argument to 'taper', something that Boston Fed President Eric Rosengren said could happen in a few months' time.Traders are now awaiting the latest figures for US gross domestic product (GDP) this afternoon, as well as jobless claims and pending-home sales, which could clear up some uncertainty in regards to the Fed's intentions.Elsewhere, economic-confidence figures in the Eurozone were largely in line with forecasts this morning, showing a slight improvement in May, though modest gains for the FTSE 100 were trimmed after an Italian debt auction. The Italian Treasury sold β¬5.75bn of five- and 10-year debt today, the top end of its target, but the long-term issuance saw the highest yields since March while investor demand diminished.Miners track metals higherAcross-the-board gains in metals prices saw miners perform relatively well this morning with Fresnillo, ENRC, Polymetal, Randgold and Glencore Xstrata on the up.Tullow Oil was also up despite saying that it has been forced to plug and abandon another one of its exploration wells, this time off the coast of Cote D'Ivoire.B&Q owner Kingfisher was in the red after revealing a 0.4% fall in first-quarter sales as a result of weak consumer confidence and unseasonably cold weather in March and early April.Severn Trent was subdued after the utilities company reported an annual profit that slightly missed analysts' expectations.Ingredients group Tate & Lyle fell despite its full-year profits coming in ahead of forecasts. Analysts at Canaccord Genuity said this morning that consensus forecasts for the current year are likely to be trimmed.Tesco was out of favour after JPMorgan Cazenove downgraded the stock from 'overweight' to 'neutral' to reflect its "cautious view on the UK food retail marketas a whole, of which Tesco represents 30%".In contrast, Wood Group was in demand after Morgan Stanley upgraded its rating on the stock from 'equal weight' to 'overweight', saying that the business is well positioned to cope with a lower growth outlook for spending in the oil services sector.FTSE 100 - RisersFresnillo (FRES) 1,139.00p +4.59%International Consolidated Airlines Group SA (CDI) (IAG) 282.60p +3.14%Randgold Resources Ltd. (RRS) 5,095.00p +3.12%Polymetal International (POLY) 675.50p +2.66%Eurasian Natural Resources Corp. (ENRC) 256.60p +2.07%Wood Group (John) (WG.) 850.00p +1.98%ARM Holdings (ARM) 995.50p +1.84%RSA Insurance Group (RSA) 116.30p +1.75%ITV (ITV) 132.60p +1.69%Lloyds Banking Group (LLOY) 61.66p +1.68%FTSE 100 - FallersTate & Lyle (TATE) 830.00p -2.24%Tesco (TSCO) 365.50p -2.01%National Grid (NG.) 782.00p -1.88%Croda International (CRDA) 2,506.00p -1.30%Hargreaves Lansdown (HL.) 963.50p -1.18%Centrica (CNA) 374.60p -1.06%BT Group (BT.A) 302.30p -1.02%Aberdeen Asset Management (ADN) 467.90p -0.99%Reckitt Benckiser Group (RB.) 4,777.00p -0.99%Land Securities Group (LAND) 937.00p -0.95%FTSE 250 - RisersFirstGroup (FGP) 125.60p +6.44%Tullett Prebon (TLPR) 287.40p +4.55%ICAP (IAP) 361.90p +3.55%SDL (SDL) 383.10p +3.54%Lonmin (LMI) 280.10p +3.36%Regus (RGU) 167.10p +2.83%Kazakhmys (KAZ) 342.90p +2.54%Britvic (BVIC) 527.00p +2.53%Salamander Energy (SMDR) 171.10p +2.46%Brewin Dolphin Holdings (BRW) 235.90p +2.43%FTSE 250 - FallersNew World Resources A Shares (NWR) 103.50p -4.08%RPS Group (RPS) 211.50p -2.62%Persimmon (PSN) 1,211.00p -2.50%Ashmore Group (ASHM) 405.60p -2.43%Ashtead Group (AHT) 634.00p -2.39%Drax Group (DRX) 566.50p -2.33%Investec (INVP) 466.80p -2.02%Jupiter Fund Management (JUP) 331.20p -1.98%Great Portland Estates (GPOR) 545.00p -1.62%PZ Cussons (PZC) 370.70p -1.59%