Global oil prices tumbled more than four per cent to fresh five-year lows on mounting oversupply worries as global economic growth slows. The main US futures contract, West Texas Intermediate for delivery in January, fell 2.79 dollars, settling at 63 dollars a barrel on the New York Mercantile Exchange, its lowest close since late July 2009. Investment bank Morgan Stanley, in a research note on the crude oil outlook projected that the market oversupply situation will peak in the second quarter of 2015 without OPEC intervention to tighten output.