Though Amazon's (AMZN) margins have been hurt by the cost of supporting Prime shipping, RBC's...

|By:, SA News Editor

Though Amazon's (AMZN) margins have been hurt by the cost of supporting Prime shipping, RBC's Ross Sandler believes Prime will be a long-term positive for Amazon, following a survey. Sandler, who estimates Amazon has 15M Prime subscribers worldwide (in spite of reports of just 3M-5M), says his survey indicates Prime users increase order activity by an estimated 153% after signing up (though average transaction size is likely also lower).