Top global miner BHP Billiton killed its $39 billion bid for Potash Corp, the world's biggest deal this year, and said on Monday it would return $4.2 billion to investors through a share buyback.

Canada blocked BHP's bid for the world's largest fertilizer maker on Nov. 3 and gave BHP a month to prove the takeover would benefit Canada.

BHP gave up the fight in its third straight failure to seal a major acquisition under Chief Executive Marius Kloppers, and bowed to calls from some shareholders for a return of capital, signaling it has limited opportunities for other big takeovers.

BHP said it would book $350 million in costs for the Potash Corp deal.

Kloppers has long said the company would prefer to spend its cash pile on development projects and acquisitions rather than giving it back to shareholders.