Vincor will issue a formal response to the Constellation bid in the next nine days. The wine company has written to all of its shareholders this week, advising them to do nothing with their shares until Vincor issues a formal recommendation.

Constellation's bid for North America's fourth largest wine company is open until 28 November.

"Your board of directors is reviewing the Constellation offer and considering alternatives to it with a view to making a formal recommendation to you - our shareholders," Donald Triggs and Mark Hilson, president and CEO, and chairman of the special committee of the board respectively, said in the letter.

"The special committee and its financial advisors are currently in active discussions with numerous interested parties regarding the purchase of Vincor," the letter continued. "We will be sending to you our more detailed response to the Constellation offer by 4 November, making a formal recommendation to our shareholders."