The FTSE 100 was taking advantage of low volumes on Wednesday morning, registering decent gains by lunchtime as other stock markets across Europe remained closed for the May Day public holiday.A slowdown in Chinese manufacturing growth didn't have too much of an effect on markets early on as traders showed optimism in anticipation of a continuation of monetary stimulus from the US and a rate cut in Europe this week.The official Chinese manufacturing purchasing managers' index (PMI) fell from 50.9 to 50.6 in April. While the figure remains above the key 50-point level that separate expansion from contraction, it was just under the 50.7 consensus forecast. However, there was an improvement in UK manufacturing with the PMI rising from 48.6 to 49.8 in April, ahead of the 48.5 consensus forecast. "This is quite encouraging for the UK, especially given that the boost in new orders came from outside the Eurozone, where the UK has been far too reliant on in the past," said Market Analyst Craig Erlam from Alpari.The Federal Reserve concludes its two-day policy meeting this evening and is widely expected to keep its quantitative easing programme unchanged. Last Friday's worse-than-expected gross domestic product report for the first quarter has allayed fears that the Fed could start to taper is asset purchases before the end of the summer.Meanwhile, the European Central Bank (ECB) convenes tomorrow to discuss a possible interest-rate cut given that recent Eurozone economic data continues to paint a gloomy picture for the single-currency region. What's more, yesterday's inflation figures showed that consumer-price rises slowed down sharply in April, adding to speculation that the ECB will cut its key 'refi' rate from the already-record-low level of 0.75%.FTSE 100: Antofagasta on target after first quarterChilean copper miner Antofagasta was a strong riser early on after seeing production rise 12.8% year-on-year in the first quarter and saying that it remains on course to hit its full-year output guidance.Other resource stocks including Randgold, Fresnillo, Vedanta, Rio Tinto and Polymetal were also making gains, shrugging off the disappointing Chinese economic data, as hopes over monetary stimulus improved the outlook for demand.However, sector peer ENRC was trading lower on reports that the UK Listings Authority has launched an investigation into potential breaches of takeover rules. Headlines this morning were also focusing on issues with the company's flotation in 2007.In demand this morning was industrial investment firm Melrose which sold its Truth Hardware division to AIM-listed building product group Tyman for $200m.Oil and gas company BG Group was flat despite saying that it completed a well test in Tanzania which revealed better-than-expected resources. Meggitt, the aerospace components engineer, also underwhelmed after saying that it continues to expected mid-single-digit revenue growth this year after a solid first quarter.Engineering firm Weir was flat after announcing that its long-running Chairman Lord Smith of Kelvin will step down in December, as it revealed that first-quarter revenues and profits were down year-on-year. Admiral, Croda, ITV and Reed Elsevier were among the worst performers of the morning after going ex-dividend, meaning that new investors have now missed the opportunity to tap in to each companies' latest payout. Reed Elsevier was also being weighed down by a ratings cut by UBS from 'buy' to 'neutral'.FTSE 100 - RisersRandgold Resources Ltd. (RRS) 5,230.00p +3.36%GKN (GKN) 281.10p +2.29%ARM Holdings (ARM) 1,017.00p +2.11%Antofagasta (ANTO) 915.50p +2.01%Fresnillo (FRES) 1,174.00p +1.91%Associated British Foods (ABF) 1,971.00p +1.86%Kingfisher (KGF) 318.90p +1.85%BT Group (BT.A) 280.90p +1.70%Experian (EXPN) 1,151.00p +1.68%Standard Chartered (STAN) 1,643.00p +1.61%FTSE 100 - FallersAdmiral Group (ADM) 1,238.00p -3.36%Reed Elsevier (REL) 729.00p -3.06%Eurasian Natural Resources Corp. (ENRC) 266.30p -2.95%ITV (ITV) 123.00p -2.30%Weir Group (WEIR) 2,157.00p -2.13%Evraz (EVR) 152.00p -1.94%G4S (GFS) 308.00p -1.53%Croda International (CRDA) 2,449.00p -1.17%Intertek Group (ITRK) 3,278.00p -0.91%Burberry Group (BRBY) 1,325.00p -0.82%FTSE 250 - RisersRenishaw (RSW) 1,748.00p +6.20%Carillion (CLLN) 279.20p +4.10%Petropavlovsk (POG) 150.00p +3.45%Dixons Retail (DXNS) 36.23p +3.22%Man Group (EMG) 105.20p +2.94%Halma (HLMA) 514.00p +2.70%BBA Aviation (BBA) 257.60p +2.67%Centamin (DI) (CEY) 42.43p +2.66%Ophir Energy (OPHR) 416.40p +2.33%National Express Group (NEX) 195.60p +2.14%FTSE 250 - FallersNMC Health (NMC) 276.90p -10.68%Heritage Oil (HOIL) 150.40p -6.00%African Barrick Gold (ABG) 165.40p -5.49%Elementis (ELM) 255.50p -3.04%Ocado Group (OCDO) 165.60p -2.59%Perform Group (PER) 505.50p -2.41%Home Retail Group (HOME) 152.70p -1.99%Betfair Group (BET) 850.00p -1.73%Capital & Counties Properties (CAPC) 302.80p -1.69%Cobham (COB) 246.60p -1.56%BC