FTSE 100 flounders as miners, exporters drag; Metro Bank plummets

(Reuters) - The FTSE 100 ended lower for the third straight session as copper miners fell and exporter stocks struggled despite weakness in sterling, while Metro Bank tanked after an accounting error caused quarterly profit to halve.Strong results from Shell and Smith & Nephew capped losses, but the FTSE 100 was still held to a one-month low, falling 0.5 percent. The FTSE 250 was 0.6 percent lower.Sterling had initially gained on upbeat Brexit sentiment, but its rise was halted after the Bank of..