THE UPWARD revision to American GDP on August 27th provided a shot in the arm to global stockmarkets, which have endured their most volatile week of trading in years. The American economy is now thought to have grown by 3.7% at an annual rate in the second quarter, a much higher estimate than the 2.3% that was given in an initial evaluation of the quarter. After so much bad news about the Chinese economy, which has been a factor behind the meltdown of Chinese share indices, the US figure came as a relief to markets. Commodities also rallied: Brent crude soared by 10%, its biggest one-day gain in over six years, to ... (full story)