A London hedge fund Armajaro has bought 240.100 tons of cacao, a large chunk of the world’s stocks of cocoa beans, which led the prices to their highest level in 33 years. THis purchase is the biggest delivery from London’s Liffe exchange since 1996 and equal to about 7 per cent of annual global production.

Armajaro’s bold bet on higher prices comes as cocoa prices have risen 150 per cent over the past two-and-a-half years, prompting recession-hit chocolate makers to reduce the size of...