Fishing for takeover plays in the wake of the American Cyanamid deal, investors last week latched on to Chiron Corp., driving CHIR shares up 17 percent.

The stock climbed $9.625 on volume of 5.6 million shares, including runs of 2.2 million shares on Tuesday and 1.1 million shares on Friday. The stock was traded in large blocks, implying that buyers were either institutional or corporate.