question,,,, friend of mine was told by her broke

question,,,, friend of mine was told by her broker not to purchase any more of CRGP because once a merger is final, shares traded after that date (refering to Sept 10th) are worthless and won't be counted in any buy out or transfer to the new company. I can't imagine this is correct because it's still trading. Grey market is matched trades so i dont see why they told her that. And, I'd like to pick up a few more shares myself... Any truth to what she was told?