Global markets buckled, with stocks plunging from Tokyo to London and Chicago, as the BBC projected a victory for the “Leave” campaign with most votes counted in Britain’s referendum on membership of the European Union. The pound fell the most on record, while haven assets jumped.Sterling tumbled 10 percent, the euro slid by the most since it was introduced in 1999 and the yen had its biggest surge since 1998. South Africa’s rand led losses among the currencies of commodity-exporting nations, sliding more than 6 percent as oil sank to about $47 a barrel and industrial metals slumped. Gold soared with U.S. Treasuries as investors piled into haven assets. Futures on the FTSE 100 Index plunged with S&P 500 Index contracts as Asian stocks dropped by the most in five years.