The mining sector is being weighed lower by blue chip Anglo American which is losing nearly 3%. The group is in the red despite reporting that underlying earnings leapt to $4.98bn last year from $2.57bn in 2009 on revenue up 34% to $32.93bn.It's also agreed a 50:50 joint venture with Lafarge to merge the pair's UK cement, aggregates, ready-mixed concrete, asphalt and contracting businesses to create a British construction materials firm.Sector peers Rio Tinto and Vedanta Resources are also lower, after taking fright at further attempts by the Chinese authorities to cool down the Chinese economy. China has raised bank reserve requirements by half a percentage point, to a record level of 19.50%. It's the fifth hike in the requirement since October and is designed to stop the banks having too much cash sloshing around to lend to customers.Meanwhile, the electricity sector is the best performing sector, with coal-fired power plant operator Drax and energy provider Scottish & Southern Energy both providing a spark.Top performing sectors so far todayElectricity 7,464.03 +1.27%Tobacco 28,488.74 +1.27%Industrial Metals & Mining 8,406.71 +1.15%Food & Drug Retailers 4,833.79 +1.00%Automobiles & Parts 5,024.50 +0.84%Bottom performing sectors so far todayMining 26,370.85 -2.48%Oil Equipment, Services & Distribution 24,658.10 -1.54%Banks 5,201.56 -1.51%Chemicals 6,780.52 -1.32%Industrial Engineering 6,573.02 -1.05%