I would have thought the formula is very simple regardless of...

I would have thought the formula is very simple regardless of the size of company leading to tonnage of production. End of day revenue - total operational cost should be sustaining to settle other costs like financing debts etc which again will lead to high grade mining to be simplistic.

If spot IO drops to the consensus target of $80/tonne and stays there for a longer period than expected, those with surplus cash will see better value reflected in their SP while others that are risky to not able to maintain the accumulated debts will suffer. This is just one scenario that can happen unless you are able to forecast 100% the IO future spot price. You can't just keep cutting cost to the bone and still maintain a healthy cash flow which has already tested FMG last year.

Gina like all other wanna be IO will have done their 'homework' at the time of decision and calculated that based on certain assumptions they could still make money all factors considered. The massive lead time projects also depends to a certain degree timing and luck is all I can say.