LONDON  To some, he is a real-life Willy Wonka. To others, he is a Bond-style villain bent on taking over the world’s supply of chocolate.

In a stroke, a hedge fund manager here named Anthony Ward has all but cornered the market in cocoa. By one estimate, he has bought enough to make more than five billion chocolate bars.

Chocolate lovers here are crying into their Cadbury wrappers  and rival traders are crying foul, saying Mr. Ward is stockpiling cocoa in a bid to drive up already high prices so he can sell later at a big profit. His activities have helped drive cocoa prices on the London market to a 30-year high.

Mr. Ward, 50, is not some rabid chocoholic, former employees say. He simply has a head for cocoa. And, through his private investment firm, Armajaro, he now controls a cache equal to 7 percent of annual cocoa production worldwide, a big enough chunk to sway prices.