Britain's main benchmark index fell for second day on Tuesday led down by heavyweight materials stocks as metal prices weakened, Reuters reported. Stronger global economic growth is generally positive for stocks, the performance of which depends on corporate profits. Yet the FTSE's exposure to basic materials stocks, which account for nearly 10 percent of the index's weight, mean it could underperform if metal prices continue to fall. Basic materials stocks knocked 5.3 points of the FTSE, which was down 15.28 points, or 0.2 percent, at 6,580.30 points at 0853 GMT. The British index has fallen roughly 2 percent over the past month, lagging a small rise for the STOXX Europe 600.