Uncertainty surrounding US monetary policy and a raft of poorly-received corporate earnings kept the FTSE 100 flat on Thursday morning, with the index fluctuating at its lowest in three weeks.The FTSE 100 was up just 0.09% at 6,952.66 by midday, with RBS, IAG and Schroders limiting upside after disappointing with results, while a number of other blue chips went ex-dividend. Nevertheless, the index did bounce off an intraday low of 6,906.24 reached early on.A 2.2% sell-off over the past two sessions saw the Footsie retreat from Monday's all-time closing high of 7,103.98 to 6,946.28 as of Wednesday's close. This was the lowest finish for the index since 8 April.Wednesday's Federal Reserve policy statement was in focus after officials issued a cautiously optimistic outlook on the economy, saying that the current economic slowdown is only temporary. This followed data showing that annualised US gross domestic product growth slowed to just 0.2% in the first quarter from 2.2% previously.Analysts at Danske Bank reckon that the Fed is still on track to hike rates by 25 basis points in September.However, Barclays said that the statement still left the door open for a rate hike as soon as June: "In our view, the lack of any specific calendar time suggests June will be a 'live' meeting, where rate hike deliberations will begin in more earnest."In economic data on Thursday, Eurozone consumer prices registered zero growth in April compared to a year ago, as expected by analysts. This was an improvement from the 0.1% annual decline seen in March.Meanwhile, Eurozone unemployment was unchanged at 11.3% in March, disappointing analysts who had expected a decline to 11.2%.IAG, RBS and Schroders fallAirline conglomerate IAG underwhelmed despite making its first-ever profit in the first quarter. The company beat expectations with an operating profit of €25m, compared with a €150m loss the year before.Royal Bank of Scotland made a £446m loss in the first quarter of the year, more than double what had been feared as it was hit by £453m of restructuring costs and set aside £856m for litigation and conduct charges.Financial services giant Schroders also fell as profits for the first quarter missed forecasts. The company did however beat estimates with a 6.5% increase in assets under management to £319.5bn.Royal Dutch Shell revealed a 56% drop in first-quarter earnings to $3.25bn but that wasn't as bad as the $2.5bn expected, helping the stock higher. Shell also shaved its capital investment budget for 2015 by $2bn to "$33bn or less".Medical services group Smith & Nephew edged higher as it reported a slight increase in first quarter revenue and reiterated its expectations for 2015.Shares in RPS Group dropped sharply after the industrial consultancy outfit said the continuing volatility in the oil and gas sector meant its energy business had a slower-than-expected start to the year.Zoopla, the residential property website group, soared after agreeing to acquire utility price comparison site uSwitch for up to £190m.A number of stocks were trading lower after going ex-dividend, including Centrica, Fresnillo, ITV, Reed Elsevier and Travis Perkins. Market MoverstechMARK 3,186.47 -0.02%FTSE 100 6,952.66 +0.09%FTSE 250 17,476.74 -0.03%FTSE 100 - RisersRoyal Mail (RMG) 466.60p +5.04%Associated British Foods (ABF) 2,861.00p +2.51%Aberdeen Asset Management (ADN) 473.00p +1.48%Shire Plc (SHP) 5,360.00p +1.32%Royal Dutch Shell 'B' (RDSB) 2,095.00p +1.26%Persimmon (PSN) 1,703.00p +1.25%Barratt Developments (BDEV) 518.00p +1.17%Sports Direct International (SPD) 611.00p +1.08%St James's Place (STJ) 887.00p +1.03%Imperial Tobacco Group (IMT) 3,204.00p +1.01%FTSE 100 - FallersITV (ITV) 251.10p -4.71%Royal Bank of Scotland Group (RBS) 333.70p -4.52%Centrica (CNA) 256.60p -4.11%Anglo American (AAL) 1,103.50p -3.07%International Consolidated Airlines Group SA (CDI) (IAG) 544.50p -2.59%Fresnillo (FRES) 724.50p -1.96%Meggitt (MGGT) 526.50p -1.59%Antofagasta (ANTO) 772.00p -1.53%Morrison (Wm) Supermarkets (MRW) 187.70p -1.52%Reed Elsevier (REL) 1,073.00p -1.47%FTSE 250 - RisersZoopla Property Group (WI) (ZPLA) 209.80p +13.41%NMC Health (NMC) 743.00p +4.57%TalkTalk Telecom Group (TALK) 367.40p +3.52%Bwin.party Digital Entertainment (BPTY) 82.25p +2.36%Premier Oil (PMO) 178.40p +2.29%Countrywide (CWD) 525.50p +2.24%Cairn Energy (CNE) 182.40p +2.18%UDG Healthcare Public Limited Company (UDG) 539.00p +2.08%Greencore Group (GNC) 355.40p +1.98%Galliford Try (GFRD) 1,497.00p +1.84%FTSE 250 - FallersOphir Energy (OPHR) 144.00p -11.06%RPS Group (RPS) 214.20p -9.28%Fisher (James) & Sons (FSJ) 1,196.00p -8.21%Berendsen (BRSN) 1,039.00p -4.59%Vedanta Resources (VED) 614.00p -2.92%Rexam (REX) 568.00p -2.66%Polymetal International (POLY) 524.50p -2.51%Cobham (COB) 294.80p -2.51%William Hill (WMH) 357.50p -2.51%National Express Group (NEX) 286.80p -2.45%