BHP Billiton shares jumped on Friday after the world's biggest mining company by revenues said that it is considering a demerger of certain assets in an effort to make the business "simpler and more productive". The company, reiterated its focus on its "four pillars" - iron ore, copper, coal and petroleum - with potash being a potential fifth, suggesting that nickel, aluminium and bauxite assets could be spun off. It will update the market after the board reconvenes next week.The wider mining sector was also on the rise on Friday, including Rio Tinto, Anglo American and Glencore, as stimulus speculation surrounding top metals consumer China continued to boost risk appetite.However, precious metal producers such as Fresnillo and Randgold were bucking the trend as gold and silver prices declined. Gold was down 0.8% while silver dropped 1.2% at spot prices on Friday afternoon.Shares in Smith & Nephew were under pressure after Morgan Stanley downgraded the medical devices maker from 'overweight' to 'equal weight'. The bank said that even if US peer Stryker returns with a bid in November, the deal "remains uncertain" and the stock "could start to lose its M&A premium of around 10%" in the near term.Housing-related stocks such as equipment rental firm Ashtead Group and housebuilder Barratt Developments were making gains. Concerns about an early rate hike by the Bank of England have eased this week after the central bank warned about weak wage growth in the UK. Citigroup analysts on Friday pushed back their call for the first rate hike to the first quarter of 2015 instead of the fourth quarter of 2014.FTSE 100 - RisersAshtead Group (AHT) 917.00p +2.52%BHP Billiton (BLT) 2,076.00p +2.49%Barratt Developments (BDEV) 358.30p +2.05%Imperial Tobacco Group (IMT) 2,551.00p +1.92%Tesco (TSCO) 249.80p +1.88%Sports Direct International (SPD) 701.50p +1.81%3i Group (III) 377.10p +1.73%Babcock International Group (BAB) 1,111.00p +1.65%BT Group (BT.A) 373.90p +1.63%Smiths Group (SMIN) 1,275.00p +1.59%FTSE 100 - FallersFresnillo (FRES) 1,011.00p -1.56%Randgold Resources Ltd. (RRS) 5,055.00p -1.27%Petrofac Ltd. (PFC) 1,133.00p -0.96%Royal Mail (RMG) 439.50p -0.92%Smith & Nephew (SN.) 1,032.00p -0.86%St James's Place (STJ) 734.00p -0.68%G4S (GFS) 265.40p -0.45%easyJet (EZJ) 1,285.00p -0.31%Legal & General Group (LGEN) 238.70p -0.25%Antofagasta (ANTO) 811.00p -0.25%BC