The oil sector falls back after BP's fourth quarter results failed to meet expectations.Underlying replacement cost profit in the fourth quarter was up 70% on a year earlier at $4.38bn, but fell short of analysts' forecasts of around $4.7bn.Recovery in the major economies of the US and Europe is expected to be 'slow and gradual', Hayward said, and while OPEC seems to be intent on keeping the oil market steady, the company expects gas markets to be volatile while refining margins are expected to remain under pressure for the foreseeable future.'2009 has been one of the best years for BP and its shareholders since the merger with Amoco, but we are not resting on our laurels,' Heyward said.Peer Shell is also lower.Elsewhere in the world of commodities, miners are going well, including Rio, which has been upgraded to 'buy' from 'hold' at Citgroup after upgrades to iron ore prices.Top performing sectors so far todayMining 20,929.18 +3.12%Technology Hardware & Equipment 387.26 +2.58%Oil Equipment Services & Distribution 15,799.79 +2.43%Industrial Metals 4,821.64 +2.35%Industrial Transportation 2,057.55 +2.08%Bottom performing sectors so far todayOil & Gas Producers 7,830.48 -1.64%Household Goods 6,248.38 -1.09%Gas, Water & Multiutilities 4,090.45 -0.83%Mobile Telecommunications 3,131.17 -0.32%Forestry & Paper 3,878.77 -0.22%