- Chinese concerns hammer copper prices- Ex-div stocks falls- Prudential gains, G4S slumps- Poundland, Pets at Home in focustechMARK 2,825.81 -0.90%FTSE 100 6,629.89 -0.83%FTSE 250 16,372.49 -0.66%Fears surrounding a slowdown in China and ongoing concerns about Ukraine weighed heavily on stock markets on Wednesday with the FTSE 100 sinking to its worst level in a month.London's benchmark index was down 0.8% at 6,630 by midday, having hit a low of 6,611 earlier on - the Footsie has not reached this intraday level since February 13th.Analyst Market Craig Erlam from Alpari said: "What we're seeing now is markets on the whole being driven by investor sentiment and as long as we don't see anything positive to act as a distraction from Ukraine and China, sentiment is likely to remain low, as we're seeing again today."Following data earlier this week from China which revealed a surprise trade deficit in February as exports slumped, sentiment was dampened further by reports of a possible second onshore debt default by another solar power firm in the country.Investors were also looking ahead to data due tomorrow which is likely to show that Chinese industrial output growth eased slightly last month.Copper prices were bearing the brunt of the sell-off today with futures for three-month delivery on the London Metal Exchange down 0.7% to $6,429 a metric ton after falling to a low of $6,376.25 early on - their lowest intraday level since July 2010.Ukraine continued to be a focal point for markets today as Prime Minister Arseniy Yatsenyuk meets with US President Barack Obama in Washington ahead of the looming Crimea referendum on March 16th. With Crimea set to vote on whether or not to split from Ukraine and join Russia, Western leaders have threatened more sanctions on Russia.This comes amid recent reports according to which Russian forces are continuing to increase their presence on Ukraine's eastern border after having already taken control of the Crimean peninsula.Meanwhile, emerging fears about new protests in Turkey were also a cause for concern this morning with the Borsa Istanbul 100 index trading down 1% early on. Clashes have erupted in the aftermath of the death of a boy nine months after he was injured in the Istanbul protests last year.Ex-div stocks fall, Prudential and G4S in focusA number of heavyweight FTSE 100 stocks were lower this morning after going ex-dividend, including British American Tobacco, Hammerson, Standard Chartered, Meggitt, Hargreaves Lansdown, Randgold and Land Securities. On the FTSE 250, Direct Line, Costain, Domino's Pizza, Al-Noors Hospitals and Serco all went ex-div today.Insurance giant Prudential was in positive territory after reporting a 17% rise in operating profit to £2.96m and a 15% increase in the full-year dividend after a "strong performance in 2013".G4S, however, failed to impress with its 2013 results after an "extremely challenging year" which saw the security solutions provider swing to a statutory pre-tax loss of £170m, from a profit of £313m in 2012.Banking stocks such as HSBC, Barclays and RBS were under the weather this morning as investors scaled back their appetite for risk. Mining peers Glencore Xstrata, BHP Billiton and Anglo American were also in the red.UK retailers Poundland and Pets at Home were in focus after pricing their initial public offerings (IPOs) at the top of their expected ranges. Poundland jumped instantly after the open on conditional trading, while Pets at Home fell, but was still within the indicative price range set out by the company. By midday shares of the latter had largely recovered their poise but were nevertheless putting in a poor showing.FTSE 100 - RisersPrudential (PRU) 1,405.00p +3.23% Group (VOD) 229.40p +1.39%Antofagasta (ANTO) 849.00p +1.07%Aviva (AV.) 527.00p +0.67%Resolution Ltd. (RSL) 377.30p +0.61%Centrica (CNA) 328.80p +0.55%Rio Tinto (RIO) 3,171.00p +0.51%Coca-Cola HBC AG (CDI) (CCH) 1,498.00p +0.47%TUI Travel (TT.) 430.90p +0.33%Morrison (Wm) Supermarkets (MRW) 231.40p +0.26%FTSE 100 - FallersG4S (GFS) 230.00p -6.28%Standard Chartered (STAN) 1,204.50p -3.56%British American Tobacco (BATS) 3,226.50p -3.24%Hargreaves Lansdown (HL.) 1,346.00p -2.82%Meggitt (MGGT) 453.20p -2.77%Hammerson (HMSO) 557.00p -2.62%Melrose Industries (MRO) 290.10p -2.39%Rolls-Royce Holdings (RR.) 1,027.00p -2.38%Land Securities Group (LAND) 1,042.00p -2.34%London Stock Exchange Group (LSE) 1,941.00p -2.22%FTSE 250 - RisersHikma Pharmaceuticals (HIK) 1,522.00p +3.33%Hiscox Ltd (HSX) 674.50p +1.81%Petra Diamonds Ltd.(DI) (PDL) 155.00p +1.71%Homeserve (HSV) 323.60p +1.70%WH Smith (SMWH) 1,193.00p +1.62%esure Group (ESUR) 268.00p +1.28%Ted Baker (TED) 2,174.00p +1.26%Taylor Wimpey (TW.) 117.00p +1.12%Britvic (BVIC) 742.00p +1.09%Fenner (FENR) 422.80p +1.05%FTSE 250 - FallersKenmare Resources (KMR) 13.48p -7.03%Ocado Group (OCDO) 542.50p -5.16%Direct Line Insurance Group (DLG) 256.10p -4.15%Serco Group (SRP) 445.00p -3.76%ICAP (IAP) 416.40p -3.45%Evraz (EVR) 56.35p -3.26%Spirent Communications (SPT) 101.80p -3.14%Henderson Group (HGG) 242.50p -3.04%RPS Group (RPS) 330.60p -3.02%Devro (DVO) 256.20p -2.95%BC