London open: Banks, ex-div stocks weigh on FTSE 100

- HSBC Chinese PMI improves but still below 50- Standard Chartered falls after first-quarter update- BSkB leads risers after 'fit and proper' defenceFollowing a strong rise for UK stocks yesterday when European markets were closed for May Day, the FTSE 100 opened lower on Wednesday morning.London's benchmark finished 1.3% higher on Tuesday after an upwards surprise in manufacturing figures from the US, offsetting some worse-than-expected readings in China and the UK.Today, HSBC's Chinese manufacturing purchasing managers' index (PMI) improved from a flash estimate of 49.1 to 49.3 in April, up from the 48.3 level in March. However, any reading below 50 still marks a contraction.Yesterday, China's official manufacturing PMI by the China Federation of Logistics & Purchasing rose from 53.1 to 53.3, and while slightly below expectations, it showed that the sector was still expanding.On the domestic economic front, the PMI for Construction for April is due out at 09:30, as are mortgage approvals for March. The latter are seen slipping to 48,000 from March's 49,000. FTSE 100: Standard Chartered leads banks lowerStandard Chartered said its broad geographic base once again helped it secure a strong start to the year with "high single-digit income growth" in the first quarter. However, it admitted that growth had been hit by the continued strength of the US dollar against Asian currencies. Shares were lower early on. Sector peers Barclays, Lloyds and RBS were also out of favour following a strain performance the day before.Insurance group Admiral was a heavy faller early on after going ex-dividend. ARM Holdings, Kingfisher and Xstrata were also trading without the right to their latest dividends.Broadcaster and broadband group BSkyB was making gains after reporting record nine-month operating profit. Meanwhile, the firm insisted it was 'fit and proper to hold its broadcasting licences' as the fall-out from the News Corporation hacking scandal continues.Fashion chain Next rose after sticking with full-year guidance given in March after first quarter sales showed a small year-on-year improvement, helped by contributions from new stores.Shares in oil and gas group BG advanced after it announced the first production from its Margarita gas field in Bolivia.FTSE 250: Home Retail disappointsArgos and Homebase owner Home Retail dropped after it revealed a 9% decline in like-for-like sales as pre-tax profit plunged 60% after particular weakness in consumer electronics.Fund manager Henderson fell after seeing net outflows in the first quarter of 2012 despite assets under management having grown on the back of the recovery in equities.Meanwhile, Kesa Electricals, Morgan Crucible and Renishaw were performing strongly after broker upgrades. Goldman Sachs upgraded Kesa from sell to neutral, while Barclays Capital lifted both Morgan Crucible and Renishaw from equal weight to overweight and hiked its target prices.FTSE 100 - RisersBritish Sky Broadcasting Group (BSY) 706.50p +2.24%Next (NXT) 2,954.00p +2.00%Rexam (REX) 438.60p +1.22%Burberry Group (BRBY) 1,500.00p +1.15%Tate & Lyle (TATE) 703.50p +1.08%Serco Group (SRP) 557.50p +0.90%Pearson (PSON) 1,163.00p +0.87%Morrison (Wm) Supermarkets (MRW) 281.80p +0.86%InterContinental Hotels Group (IHG) 1,494.00p +0.67%BG Group (BG.) 1,460.00p +0.65%FTSE 100 - FallersAdmiral Group (ADM) 1,161.00p -3.25%Weir Group (WEIR) 1,659.00p -2.64%Man Group (EMG) 95.30p -2.56%Barclays (BARC) 221.15p -2.23%Standard Chartered (STAN) 1,483.00p -1.92%Xstrata (XTA) 1,184.00p -1.74%Lloyds Banking Group (LLOY) 33.13p -1.37%Royal Bank of Scotland Group (RBS) 24.97p -1.30%Fresnillo (FRES) 1,593.00p -1.24%BAE Systems (BA.) 293.00p -1.15%FTSE 250 - RisersKesa Electricals (KESA) 57.10p +4.87%Morgan Crucible Co (MGCR) 345.60p +4.63%Renishaw (RSW) 1,489.00p +3.12%Rank Group (RNK) 116.90p +3.00%Bumi (BUMI) 540.00p +2.86%Drax Group (DRX) 565.00p +2.45%Perform Group (PER) 312.00p +2.40%Ruspetro (RPO) 197.40p +2.28%Barratt Developments (BDEV) 135.00p +2.27%Salamander Energy (SMDR) 207.10p +2.12%FTSE 250 - FallersHome Retail Group (HOME) 95.05p -5.89%Henderson Group (HGG) 116.90p -4.49%Talvivaara Mining Company (TALV) 181.10p -3.57%Cobham (COB) 222.50p -2.84%Michael Page International (MPI) 411.70p -2.30%Ocado Group (OCDO) 124.20p -2.20%Chemring Group (CHG) 383.70p -2.09%William Hill (WMH) 275.90p -1.85%Cookson Group (CKSN) 719.50p -1.30%Hochschild Mining (HOC) 489.70p -1.27%BC