- UK retail sales fall 0.7 per cent in October- French, German GDP paint gloomy picture- Yellen says Fed has 'more work to do'techMARK 2,644.91 +0.73%FTSE 100 6,656.19 +0.40%FTSE 250 15,279.90 +0.66%Hopes over a continuation of US stimulus prompted a strong start for the FTSE 100 on Thursday morning but markets quickly pared gains after a raft of worse-than-expected data this side of the Atlantic.UK retail sales fell by 0.7% in October, compared with a 0.6% gain the month before, disappointing analysts who had pencilled in no change month-on-month. Compared with last year, sales rose by 1.8% but that still missed the 3.1% increase that markets were expecting.Analyst Simon Hayes from Barclays said that the data "underscore[s] the message that squeezed real incomes are likely to act as a continuing drag on household demand". This comes after yesterday's labour-market data which showed that average earnings growth in Britain remains weak.Also weighing on sentiment was the news that German gross domestic product (GDP) growth slowed to just 0.3% in the third quarter from a rate of 0.7% in the second quarter, though this was in line with consensus estimates. The Federal Statistics Office Destatis said that the slowdown was due to weak external demand.French GDP, meanwhile, contracted by 0.1% quarter-on-quarter, down from 0.5% growth in the second quarter and slightly below analysts' forecasts for a flat reading.Nevertheless, London's benchmark index was still trading with firm gains by midday as it rebounded from Wednesday close of 6,630, its worst finish since October 18th when it finished at 6,622.58.As speculation about an gradual withdrawal of US stimulus continues to ramp up following last week's stronger-than-expected jobs data, soon-to-be Federal Reserve Chair Janet Yellen has said that the labour market and wider economy are performing "far short of their potential" with unemployment still too high.In prepared remarks ahead of a hearing in front of Congress later today, Yellen, who is expected to take over from Ben Bernanke as head of the Fed in January, said that the Fed has "more work to do" to help the recovery, easing fears that a taper of quantitative easing is just around the corner.The Dow Jones Industrial Average and S&P 500 on Wall Street both raced to new record highs following the comments on Wednesday evening.Sainsbury extends gains, Tesco fallsSupermarket group Sainsbury was a high riser this morning as investors continued to celebrate the company's better-than-expected first-half results yesterday. The stock was benefitting from a raft of broker upgrades this morning from HBSC, Exane BNP Paribas and Citigroup who all lifted their ratings on the stock and raised target prices.In contrast, sector peer Tesco was being pressured lower by a Goldman Sachs downgrade to 'sell', with the bank saying that investors "still have some time to wait before a cash return programme (buyback of special dividends) can be instigated".British Gas-owner Centrica was also down after warning that market conditions remained challenging, particularly in business energy supply in both the UK and the US, in UK gas-fired power generation and in UK gas storage. The company said it expects 2013 adjusted earnings to be flat on last year.Consumer packaging company Rexam fell after saying trading since the start of July. Sentiment still seems fragile following the company's profit warning in June.Burberry's share price was higher after the luxury fashion company said that first-half revenues exceeded £1bn for the first time on the back of strong growth in retail. Oil and gas group Ophir Energy surged after announcing the sale of a 20% interest in three blocks in Tanzania to Pavilion Energy for a maximum of $1.3bn.Digital sports media firm Perform, however, dropped sharply after saying that earnings would be lower than expected this year.FTSE 100 - RisersAberdeen Asset Management (ADN) 421.30p +3.54%Sainsbury (J) (SBRY) 421.70p +2.68%Persimmon (PSN) 1,181.00p +2.34%Prudential (PRU) 1,269.00p +2.09%Shire Plc (SHP) 2,817.00p +2.03%WPP (WPP) 1,333.00p +1.99%British Sky Broadcasting Group (BSY) 820.00p +1.86%Pearson (PSON) 1,325.00p +1.84%Associated British Foods (ABF) 2,305.00p +1.81%Royal Dutch Shell 'B' (RDSB) 2,144.50p +1.71%FTSE 100 - FallersCentrica (CNA) 348.50p -4.23%Mondi (MNDI) 989.50p -2.03%Rexam (REX) 511.00p -1.45%Anglo American (AAL) 1,389.00p -1.38%William Hill (WMH) 374.10p -1.27%Antofagasta (ANTO) 804.50p -1.11%Fresnillo (FRES) 892.00p -1.11%Glencore Xstrata (GLEN) 322.25p -0.82%United Utilities Group (UU.) 687.50p -0.65%RSA Insurance Group (RSA) 103.50p -0.58%FTSE 250 - RisersOphir Energy (OPHR) 380.40p +15.59%Taylor Wimpey (TW.) 108.60p +5.03%Amlin (AML) 452.20p +4.72%Ted Baker (TED) 1,872.00p +4.58%Booker Group (BOK) 157.30p +4.52%Renishaw (RSW) 1,813.00p +3.36%NMC Health (NMC) 357.80p +3.32%Synthomer (SYNT) 231.00p +3.17%Redrow (RDW) 274.10p +3.08%SIG (SHI) 212.10p +3.06%FTSE 250 - FallersPerform Group (PER) 468.00p -13.33%Serco Group (SRP) 440.90p -12.52%Phoenix Group Holdings (DI) (PHNX) 723.00p -6.95%3i Group (III) 349.70p -5.69%BBA Aviation (BBA) 318.50p -4.75%Bank of Georgia Holdings (BGEO) 2,061.00p -4.63%Pace (PIC) 292.10p -4.35%Domino's Pizza Group (DOM) 568.00p -2.66%AL Noor Hospitals Group (ANH) 820.00p -2.44%Galliford Try (GFRD) 1,089.00p -2.42%BC