Bristol-Myers Squibb offers $4.5 billion for ImClone

NEW YORK Bristol-Myers Squibb may acquire ImClone Systems in a proposed deal announced Thursday.

Bristol-Myers, which owns about 17 percent of ImClone and partnered with it in 2001 to develop the cancer drug Erbitux, has offered to buy it for $4.5 billion. ImClone has yet to comment on the proposal. Erbitux's second-quarter global sales rose 33 percent to $423.3 million.

Investor Carl Icahn is the biggest ImClone shareholder after BMS, with a 13 percent stake as of March 31, according to Bloomberg data. He reportedly paid an average of $33.45 per share for his stake, according to a filing with the Securities and Exchange Commission. At that rate, he could make $390.4 million if he sells at the offer price.

ImClone shares increased by 38 percent, to $17.65, in morning trading Thursday.