Stocks managed to hold on to their gains at the end of the session despite news the International Monetary Fund had pulled the technical team which was negotiating with Athens in Brussels.RBS was among the best performers in London after the government announced plans to sell down its stake, while Sainsbury's led grocers higher after a broker upgrade.The FTSE 100 ended the day 0.24% higher at 6,846.89.International Monetary Fund spokesman Gerry Rice said there were still major differences between the Washington-based lender and Greece on several key areas.The biggest sticking point seems to be over Greek pensions. IMF spokesman Gerry Rice highlighted how pensions and government wages account for 80% of total primary spending.Rice stressed the IMF is still very much at the negotiating table but the proverbial ball is now in Greece's court. Indeed, the organisation is willing to be flexible as regards the fiscal targets set for Athens, "the whole thing has to add up" including in terms of the amount of financing made available and the degree of debt relief offered."Traders are still wary about buying into the market but there are bargains to be had, and the smallest inclination of a deal being made has brought the bulls out of the woodwork," said analyst David Madden from IG.Improving economic data from China also helped to bolster sentiment in the market as figures showed the annual growth rate of industrial production and retail sales picked up in May.George Osborne announced the government will begin the process of returning RBS to private ownership in the "coming months," even though it may cause a loss for taxpayers. Spreadex analyst Connor Campbell said "investors in the stock are clearly pleased by the news".CRH leads gains, RBS in demandShares in Irish building materials group CRH advanced following media reports that it will take part in the preliminary bidding for South Korean Tongyang Cement & Energy on 12 June, for which it has reportedly hired Goldman Sachs as an underwriter.J Sainsbury was a high riser after Cantor Fitzgerald upgraded the stock to 'buy' from 'hold', saying it believes the industry is near the bottom of its current deflation and margin cycle.Tesco and Morrisons also performed well.Heading the other way was Royal Mail after the government offloaded half of its stake in the postal operator for £750m. The stock pulled back after PostNL announced the suspension of Whistl's UK direct delivery operations.Vodafone was also on the decline after Ofcom said it was investigating the telecoms giant relating to billing and customer complaint handling.Market MoverstechMARK 3,210.84 -0.07%FTSE 100 6,846.74 +0.24%FTSE 250 18,089.45 +0.33%FTSE 100 - RisersCRH (CRH) 1,885.00p +2.33%British Land Company (BLND) 850.00p +2.29%Land Securities Group (LAND) 1,296.00p +2.13%Tesco (TSCO) 215.65p +1.99%Royal Bank of Scotland Group (RBS) 361.50p +1.89%St James's Place (STJ) 900.50p +1.75%Prudential (PRU) 1,615.00p +1.70%Hammerson (HMSO) 660.50p +1.62%Taylor Wimpey (TW.) 190.00p +1.50%Imperial Tobacco Group (IMT) 3,267.00p +1.49%FTSE 100 - FallersRoyal Mail (RMG) 493.30p -4.49%Vodafone Group (VOD) 237.00p -2.91%Standard Chartered (STAN) 1,071.50p -2.06%Weir Group (WEIR) 1,876.00p -1.99%Johnson Matthey (JMAT) 3,200.00p -1.45%Antofagasta (ANTO) 727.50p -1.15%Babcock International Group (BAB) 1,126.00p -1.14%Hikma Pharmaceuticals (HIK) 1,961.00p -1.11%Smiths Group (SMIN) 1,177.00p -0.93%easyJet (EZJ) 1,576.00p -0.88%FTSE 250 - RisersNostrum Oil & Gas (NOG) 550.00p +3.58%Grainger (GRI) 218.70p +3.31%Home Retail Group (HOME) 164.40p +3.07%Crest Nicholson Holdings (CRST) 562.00p +2.84%St. Modwen Properties (SMP) 464.50p +2.77%SEGRO (SGRO) 431.60p +2.66%Mitchells & Butlers (MAB) 464.40p +2.58%Just Retirement Group (JRG) 177.00p +2.43%Redrow (RDW) 446.50p +2.34%TR Property Inv Trust (TRY) 310.00p +2.24%FTSE 250 - FallersBooker Group (BOK) 177.30p -3.27%Intermediate Capital Group (ICP) 562.00p -2.94%Cineworld Group (CINE) 473.00p -2.91%Premier Oil (PMO) 162.40p -2.64%Vesuvius (VSVS) 417.00p -2.55%Euromoney Institutional Investor (ERM) 1,161.00p -2.44%Acacia Mining (ACA) 301.00p -2.34%Serco Group (SRP) 129.50p -2.12%Imagination Technologies Group (IMG) 222.40p -2.07%Evraz (EVR) 160.20p -2.02%