Wasn't that too low? ImClone Said

Bristol-Myers offered last week to acquire the ImClone shares it does not already own in a deal that values the company at $5.2 billion.

Activist investor Carl Icahn, who is chairman of ImClone and a large shareholder of the company, told its board that he opposed Bristol-Myers' offer because he believes it "greatly undervalues the company."

"We all expected Carl would come back and say the initial offer was inadequate," said Cowen & Co analyst Eric Schmidt. "There has been posturing on both sides."

ImClone shares fell 1.1 percent to $64.60 in morning trading on Monday. Analysts said last week that ImClone could fetch much more than what Bristol-Myers had offered.

ImClone said its board had been discussing the possibility of splitting the company in two, separating its Erbitux cancer treatment and its drug-development pipeline businesses.

Erbitux is approved for colorectal and head and neck cancer in the United States, and Canada, while a recent approval for the drug in Japan and new lung cancer data are expected to drive sales.

ImClone said it believed the pipeline business "may be extremely valuable and significantly increase stockholder value as a separate business.