Soured Shredded Wheat deal leaves cloud over Falls plant. (breakfast cereal plant in Niagara Falls, New York)

General Mills Inc. and RJR Nabisco Holdings Corp., citing antitrust concerns, called off the sale of Nabisco's North American cold cereal business to General Mills in what would have been a $450 million deal.

The transaction, which would have transferred ownership of Shredded Wheat brand cereals to General Mills, would have ended Shredded Wheat's celebrated century-long existence in Niagara Falls, N.Y., where it originated.

The cereal would have continued to be made across the border in Niagara Falls, Ont.

The decision to terminate the sale has uncertain implications for the Niagara Falls, N.Y., plant and its 260 employees.

"At this point, whether …