Encana CEO Randy Eresman

Encana CEO Randy Eresman

Dave Olecko/Bloomberg

Randy Eresman, chief executive officer of EnCana Corp., is seen in this April 25, 2007 photo. Eresman’s departure “makes it more vulnerable” to a takeover, said Daniel Cheng, a money manager at Matco Financial Inc. in Calgary, who helps oversee C$375 million ($373 million), including Encana shares.