Overstock.com (OSTK, news, chart) calls are active on dubious chatter that Amazon.com (AMZN) might be eyeing the company. Shares are up 17 cents to $20.06 and 5,275 OSTK calls have traded, compared to 792 puts. The August 22.5s, which come off the board a week from Friday, are the most actives. 3,975 contracts have traded, with 65 percent of today’s volume trading offerside.