UK stocks were trading in the red on Monday despite gains in the heavyweight mining sector as Greek fears dampened sentiment.London's FTSE 100 was down 0.63% at 6,868.56 by midday.Greece's new government has threatened that they could call a referendum or have early elections if the Eurozone rejects its proposed reforms."We are not attached to our posts. If needed, if we encounter implacability, we will resort to the Greek people either through elections or a referendum," said finance minister Yanis Varoufakis.According to economist Christian Schulz from Berenberg, Athens "continues to severely damage the trust of its Eurozone partners, the only viable source of short-term funding to keep Greece afloat and in the euro".These fears saw Greece's 10-year bond yields rise by a whopping 48 basis points on Monday morning to 9.56%.In contrast, bond yields across the Eurozone were higher as the European Central Bank kicked off its landmark bond-buying programme. The bank last week confirmed that its long-awaited scheme to buy up to €1.1tn of government bonds until September 2016 and beyond would start on Monday.In economic data, China's trade surplus rose to a record $60.62bn in February, compared with $60bn in January. This increase came after a 48.3% year-on-year surge in exports and a 20.5% drop in imports, compared with expectations of +14% and -10% respectively.Meanwhile, the German trade surplus shrank to €19.7bn in January from €21.6bn the month before as exports fell 2.1% and imports declined 0.3%.StanChart and WPP gainBanking group StanChart was in demand amid speculation it could move its global headquarters to Asia and spin off its Indian business.WPP, the world's biggest advertising company, rose after beating expectations with a record £1.5bn annual profit in 2014, up 12% on the previous year. Revenues were up nearly 5% at £11.6bn, though currency movements weighed on growth.Real estate investment trusts such as Land Securities, British Land and Intu Properties were among the worst performers.Mining stocks were mostly higher on the back of strong export data from top metals consumer China. Glencore, Randgold and Fresnillo were all on the rise. Even Antofagasta edged higher despite saying that ongoing protests at its Los Pelambres copper project in Chile have reduced copper production by 5,000 tonnes over the last two weeks.ITV's share price was given a boost by Westhouse Securities which upgraded its stance on the shares from 'neutral' to 'add' after an "impressive" performance by the broadcaster and producers in 2014.Security group G4S was also higher after Deutsche Bank lifted its rating on the stock from 'sell' to 'hold'. While the broker is still cautious about longer-term potential at the company, top-line growth has surprised on the upside and shown no signs of a slowdown so far.Market MoverstechMARK 3,144.50 -0.70%FTSE 100 6,868.56 -0.63%FTSE 250 17,173.14 -0.57%FTSE 100 - RisersRandgold Resources Ltd. (RRS) 4,647.00p +1.44%Glencore (GLEN) 292.85p +1.16%WPP (WPP) 1,557.00p +1.04%Fresnillo (FRES) 705.00p +0.93%Legal & General Group (LGEN) 283.00p +0.86%Standard Chartered (STAN) 1,032.50p +0.83%Morrison (Wm) Supermarkets (MRW) 207.30p +0.63%Rolls-Royce Holdings (RR.) 993.00p +0.61%ITV (ITV) 248.00p +0.61%London Stock Exchange Group (LSE) 2,449.00p +0.57%FTSE 100 - FallersUnited Utilities Group (UU.) 903.00p -2.38%Land Securities Group (LAND) 1,237.00p -2.21%Burberry Group (BRBY) 1,846.00p -2.17%British Land Co (BLND) 823.00p -1.97%CRH (CRH) 1,762.00p -1.95%Barratt Developments (BDEV) 510.00p -1.73%Severn Trent (SVT) 1,998.00p -1.62%3i Group (III) 489.00p -1.61%Travis Perkins (TPK) 1,978.00p -1.59%Kingfisher (KGF) 357.70p -1.57%FTSE 250 - RisersIP Group (IPO) 245.90p +3.32%Entertainment One Limited (ETO) 294.60p +3.26%Betfair Group (BET) 2,132.00p +3.19%NMC Health (NMC) 629.50p +2.78%Synthomer (SYNT) 294.20p +2.51%Oxford Instruments (OXIG) 869.50p +2.29%Hunting (HTG) 508.00p +2.07%Saga (SAGA) 181.00p +1.97%Ophir Energy (OPHR) 140.40p +1.96%Ladbrokes (LAD) 116.00p +1.84%FTSE 250 - FallersAfren (AFR) 5.46p -8.32%St. Modwen Properties (SMP) 441.20p -4.69%Thomas Cook Group (TCG) 145.10p -3.40%Just Eat (JE.) 337.80p -3.04%Allied Minds (ALM) 561.00p -3.03%Hansteen Holdings (HSTN) 113.60p -2.57%Countrywide (CWD) 512.50p -2.47%Man Group (EMG) 189.80p -2.42%Essentra (ESNT) 1,002.00p -2.34%Big Yellow Group (BYG) 631.00p -2.25%