Bhp are free to buy as much NOT stock as they wish as they have no bid on the table. Wyloo cannot accumulate any as they are subject to takeover regulations. Why would BHP not accumulate a significant percentage of stock to take on Wyloo with lots more firepower. If this was happening we would see an in explicably large number of trades every day, high volumes of similar numbers of stock. Check out the recent trades posts, could it be they are coming back for another swing at twiggy?