RE: copper at 4.22swpb, if you look at the news releaseS from June 17, they actually did receive an offer even though it was non binding, and this is probably related to the offer made by a Vale subsidiary back in April 2011 for a cash buyout. I don't follow these companies so this is just from a quick look at the NRs. I could be wrong, but that's what it looks like. So there was already a deal in the workings.
I have rarely seen companies mention possible deals or interest unless it is very generic, as did Candente with Joanne Freeze and Sean Waller indicating that there was interest in CN by several companies. But no specifics. Look back to when there was a rumour from an newspaper article saying the Koreans were in talks. The company declined to make comments.
If you don't follow that rule, you will eventually get stuck in a difficult situation. If you start commenting on such things, then at the next rumour you will have to answer true/false. Then the next time you WILL have to comment again, otherwise the rumour machines will get into gear.
There may be people who talk when they are not supposed to as in this case, the Vale representative declined to be named as he was not supposed to talk, due to the companies' "no comment" policy.
Just think of the effect on a companies' share price if there is a NR indicating interest. Price pops, speculators and traders start to show up, investors start pilling on. If the show of interest ends up being just that and no deal comes through the stock will tank and many investors get hurt in the process. That is one reason why they have certain rules in place, some written rules, some unwritten.
JMHO
P-Air