If the collapse of the BHP Billiton/Rio Tinto merger was all about debt (if you believe BHP) and antitrust issues (Rio), then why did mining stocks round the world fall as BHP’s chairman Don Argus read the deal’s last rites on Tuesday, and slip even further on Wednesday?

The management on both sides should face up to facts: commodity stocks were the last domino to fall and will probably be the last to stand up again. The main reason the deal was unworkable was that miners must cope with asset writedowns and falling cash flows from operations. That makes this a terrible time to sell businesses to appease regulators and to service debt.