AS the late Wall Street legend Bruce Wasserstein was famed for saying, it’s time for BHP Billiton’s advisers to start “bidding ‘em up”. Because there is quite simply no way the miner will get its hands on Canada’s Potash for $130 (£83.32) a share, an offer that values the fertiliser giant at around $40bn.

There’s no doubt that the acquisition makes sense for BHP. As the world’s population continues to grow, food stuffs – and therefore fertiliser – will be in much demand. The deal, if it goes through, will be earnings enhancing in its second year, says BHP. So the strategy is right, but the maths is wrong.

The market knows this: Potash shares are already trading at a 15 per cent premium to the bid. So how high can BHP afford to go without crimping its chances of making the deal earnings accretive? Analysts at Standard & Poor’s say the miner could raise its offer to around $160 a share and still see the benefits on its bottom line.

That said, BHP can afford to keep its powder dry – for now. Although Potash is hoping for a white knight, the fact is none of the potential saviours will be able to move quickly. This is now a waiting game.