My understanding is that the shares are sold with

My understanding is that the shares are sold with a "due bill" attached to them. When the divi issuing date comes about (Oct 30), the seller is required to pay the due bill (the divi shares) to the buyer - if that is not done voluntarily, I suspect it would be done much like a margin call. The brokerage would have the right to sell some of the seller's other holdings to cover the cost of buying the divi shares and passing them on to the buyer - at the price of the shares at the time the divi shares are bought.

I don't think you are one of the folks that signed the agreement to wave your rights to the divi, but if you are, congratulations for being a major investor in GNBT!