Already a 17% shareholder, Bristol-Myers Squibb laid down a $4.5 billion offer to buy the rest of ImClone shares, the Wall Street Journal reports. The $60-a-share offer, sent to ImClone chairman Carl Icahn today, is a 29% premium on yesterday's closing price and makes Bristol the second pharma giant to gun for its biotech partner in as many weeks.
The news sent ImClone’s stock rocketing to a four-year high of $65.36, meaning investors believe that Bristol will have to up the ante to close a deal. ImClone stock has risen more than 40% in the past year—thanks to the good buzz surrounding its Erbitux cancer treatment—but it’s still probably best known as the stock that landed Martha Stewart in jail. (Read more mergers and acquisitions stories.)