Strong US economic data and some reassuring comments by a member of the Federal Reserve gave markets a big boost on Thursday, helping the FTSE 100 to extend gains into the third day.After hitting a fresh five-month low of 6,029 on Monday, the FTSE 100 has risen strongly over the past three sessions with bargain hunters stepping in, given that many have labelled the recent sell-off - owing to concerns about the Fed tapering stimulus as well as a slowdown in China - as overdone. The FTSE 100 finished 78 points higher at 6,243 on Thursday, up 1.26% on the day.William Dudley, head of the New York Fed, sought to ease these market fears today by saying that a rise in short-term interest rates is "very likely to be a long way off" even if the central bank begins to scale back its quantitative easing programme later this year. He said that markets were wrong to think that tighter policy is coming soon: "Let me emphasise that such an expectation would be quite out of sync with both FOMC statements and the expectations of most FOMC participants," he said.Tapering concerns also eased overnight after US economic growth for the first quarter was revised lower from 2.4% to just 1.8%, sparking hopes that the Fed would wait for signs of a firmer recovery before pulling the plug. However, given that this data is already three months old, traders will likely focus more on current economic figures, which continue to come in ahead of expectations.A raft of US data today indicated an improving picture for the world's largest economy: jobless claims fell last week; personal spending and incomes increased in May; while pending-home sales surged to a six-and-a-half-year high last month."Investors chose to focus on Dudley's comments which have soothed some nerves although it won't change the fact that investors still feel as confused as ever about future Fed policy," said Market Strategist Ishaq Siddiqi from ETX Capital.Over on this side of the Pond, there was also plenty of economic data for markets to digest: UK economic growth in the first three months of 2013 was maintained at 0.3%, but revisions to historic estimates mean that the economy did not actually suffer a double-dip recession in the first quarter of 2012. This morning also saw the release of a higher-than-expected drop in unemployment and a falling jobless rate in Germany, as well as mixed Eurozone consumer and business confidence figures.FTSE 100: Industrials provide a boostSmiths Group, the technology business which makes a range of products from contraband detection to medical devices, was a high riser on the FTSE 100 after UBS upgraded its rating from 'neutral' to 'buy'. UBS said that the sale of its Medical division, confirmed last month, would reduce the conglomerate discount that some apply to the stock's valuation and could drive a re-rating, something that is not reflected in current prices.Sector peer Rexam, the consumer packaging manufacturer, was also in demand today, rebounding after a heavy fall on Tuesday when the company admitted that full-year trading would be below expectations. Meanwhile, industrial conglomerate Melrose surged after revealing that its long-running Chairman invested £6.6m in the company this week through an investment company.Energy services group Wood Group gained after saying it is on course to deliver good growth in the first half and remains confident of achieving full-year performance in line with expectations. Engineering firms Weir and GKN also finished higher.Advertising and media giant WPP was a strong riser after Bank of America Merrill Lynch added the stock to its most preferred list, citing an "attractive combination of value and growth". Sector peer ITV was also performing well by the close of trade.International Consolidated Airlines Group (IAG) dropped as Bankia sold its 12.1% holding in the parent company of Iberia and British Airways (BA). IAG also announced that BA has ordered 24 fuel-efficient Boeing 787 Dreamliner aircraft in an effort to cut costs.FTSE 250: Perform slumps after profit warningDigital sports media firm Perform dropped sharply on Thursday after a pre-close trading update said that despite still expecting strong revenue growth this year, a change in revenue mix, together with additional rights and other investment, will impact the rate of earnings growth.Construction group Carillion rose strongly after scoring a "prestigious" £130m contract to design and build a luxury hotel in Abu Dhabi, while High Street department store Debenhams gained after lowering its operating cost guidance.FTSE 100 - RisersWPP (WPP) 1,128.00p +4.54%ITV (ITV) 142.90p +3.93%Smiths Group (SMIN) 1,319.00p +3.86%Weir Group (WEIR) 2,202.00p +3.67%Rexam (REX) 475.70p +3.41%Bunzl (BNZL) 1,287.00p +3.29%Wood Group (John) (WG.) 805.50p +3.14%GKN (GKN) 302.70p +2.78%Prudential (PRU) 1,088.00p +2.74%TUI Travel (TT.) 361.20p +2.70%FTSE 100 - FallersRoyal Bank of Scotland Group (RBS) 275.80p -1.61%Standard Life (SL.) 350.80p -0.96%Barclays (BARC) 286.25p -0.90%Petrofac Ltd. (PFC) 1,199.00p -0.50%G4S (GFS) 234.70p -0.42%Carnival (CCL) 2,311.00p -0.34%Persimmon (PSN) 1,158.00p -0.26%International Consolidated Airlines Group SA (CDI) (IAG) 263.70p -0.19%Pearson (PSON) 1,154.00p -0.17%FTSE 250 - RisersOcado Group (OCDO) 304.50p +13.03%888 Holdings (888) 156.20p +9.85%Drax Group (DRX) 573.00p +7.30%Britvic (BVIC) 499.90p +5.93%Smith (DS) (SMDS) 252.70p +5.38%Keller Group (KLR) 1,011.00p +5.31%Carillion (CLLN) 274.40p +4.77%Debenhams (DEB) 95.10p +4.74%Computacenter (CCC) 467.60p +4.56%Telecity Group (TCY) 1,014.00p +4.54%FTSE 250 - FallersPerform Group (PER) 540.00p -7.22%Hochschild Mining (HOC) 158.00p -4.13%Evraz (EVR) 97.05p -3.14%Man Group (EMG) 82.00p -3.13%Elementis (ELM) 222.60p -2.37%BH Macro Ltd. EUR Shares (BHME) € 21.09 -2.36%Polymetal International (POLY) 455.80p -1.77%Workspace Group (WKP) 385.90p -1.43%Fisher (James) & Sons (FSJ) 982.00p -1.31%BH Macro Ltd. USD Shares (BHMU) 20.81 -1.28%