If BHP Billiton’s $39bn bid for PotashCorp was a flash of the black Amex, yesterday’s full-year results were a comprehensive reminder of the group’s considerable spending power. The ratio of net debt to earnings before interest, tax, depreciation and amortisation, perhaps the best indicator of a company’s ability to add debt, was a mere 0.1 at the end of June – half the level of a year earlier.

Few other private enterprises on earth, in short, could realistically contemplate what BHP is attempting to do to PotashCorp.

On a rough calculation, BHP could lift its 16 per cent premium over the target’s pre-bid share price to 40 per cent – which is, appropriately enough, exactly where PotashCorp is trading – before the pro forma ratio of net debt to ebitda of about 1.8 times began to stretch beyond that of peers such as Xstrata (1.5) or Anglo American and Rio Tinto (both 1.7).