The FTSE 100 opened up nearly 2% down with the banks falling heavily in early trading. The dive follows a tumble on Wall Street on Friday and Asia on Monday on the back of concerns over the global economy, as US payrolls were worse than expected. Meanwhile, Christine Largarde, the head of the International Monetary Fund, warned that economies in the US and Europe need to spur growth or face a "threatening downward spiral". "we see that there has been, particularly over the summer, a clear crisis of confidence that has seriously aggravated the situation. Measures need to be taken to ensure that this vicious circle is broken," she said in an interview with a German newspaper.RBS and Barclays were dragging the blue chip index down over concerns of the multi-billion pound legal case regarding the subprime mortgage crisis in the US.There were no risers in the opening minutes.FTSE 100 mining giants Rio Tinto and Anglo American dropped after announcing that they are to offload their respective interests in South Africa-focused copper miner Palabora Mining Company.Charter International was rising higher on the FTSE 250 after confirming that US manufacturing group Colfax is in preliminary discussions with the group regarding a possible all-cash offer. Sector peer Melrose, which last week upped its bid for the firm, was lower.Energy services company Hunting opened lower after completing the acquisition of the business and assets of W L Doffing, a machine services provider, for a cash consideration of $20.8m (£12.8m).Insulation products supplier Superglass tumbled after it warned that company expectations for the year are slightly reduced from the trading update in June as market weakness and cost pressures continue to affect margins.Kofax fell as it reported a 12% increase in total revenues to $243.9m (£151m) in the year ended 30 June, just shy of the $244-246m range the company expected.West African focused-gold miner Cluff Gold was a rare riser as it announced a significant increase in the resource estimate for its wholly owned Baomahun Gold Project in Sierra Leone.BCFTSE 100 - RisersFTSE 100 - FallersRoyal Bank of Scotland Group (RBS) 22.97p -7.53%Barclays (BARC) 153.50p -7.08%Lloyds Banking Group (LLOY) 31.71p -4.26%Antofagasta (ANTO) 1,249.00p -3.92%Eurasian Natural Resources Corp. (ENRC) 634.00p -3.72%Kazakhmys (KAZ) 1,002.00p -3.65%Xstrata (XTA) 982.00p -3.58%Man Group (EMG) 212.00p -3.20%Legal & General Group (LGEN) 97.70p -3.17%Johnson Matthey (JMAT) 1,604.00p -3.08%