There are no sectors making gains today, as the markets have dropped sharply into the red on the back of economic concerns.Comments from Moody's this morning have set nerves on edge. The ratings agency still sees the UK's outlook as stable, but adds "As we've been saying for a while, in a situation of lower growth combined with weaker than expected fiscal consolidation, we would reconsider our stance." Meanwhile, the mining sector is among the worst performing sectors, helped lower by sharp falls for African Barrick Gold and Antofagasta. Antofagasta is heading the fallers on the FTSE 100, losing more than 5%, after warning that the ramp-up of the Esperanza plant in northern Chile is taking longer than expected, causing the group to scale back its total copper production guidance for 2011.Mining firm African Barrick Gold has taken a tumble, and leads the fallers on the FTSE 250 after it responded to reports of a new "Super Profits Tax" on the mining industry in Tanzania, saying it is unaware of any such tax.Falling metals prices is most likely partly attributable to the decline in the sector as well.---BCTop performing sectors so far todayAlternative Energy null 0.00%Leisure Goods null 0.00%Gas, Water & Multiutilities 4,604.74 -0.18%Real Estate Investment & Services 1,709.49 -0.18%Oil & Gas Producers 8,186.91 -0.29%Bottom performing sectors so far todayPersonal Goods 20,936.51 -2.26%Industrial Engineering 7,160.03 -2.12%Industrial Transportation 2,545.44 -2.09%Chemicals 7,448.02 -1.91%Industrial Metals & Mining 7,674.07 -1.85%