NEW YORK, July 10 (Reuters) - Amazon.com shares rose on Monday ahead of the world's largest online retailer's own version of Black Friday, while its new service to help set up 'smart homes' weighed on rival Best Buy Co Inc.
Prime Day, a 30-hour sale set to start at 9:00 p.m. EDT (0100 GMT Tuesday), is Amazon's biggest marketing push of the year, with deals to draw new subscribers to its Prime shopping club. U.S. members pay $99 per year for streaming video and two-day shipping.
Amazon shares closed up 1.8 percent at $996.47 on Nasdaq.
"Prime Day is the big overriding story and what's moved the stock up today," said Trip Miller, managing partner at Gullane Capital Partners in Memphis, Tennessee, which has a long position in Amazon.
Miller said Amazon's dominance could be seen in how a long list of retailers' shares fell on Monday.
Baird Equity Research analysts have estimated that Prime has about 60 million U.S. members, based on an April survey. Amazon does not disclose the number.
"It's a real test to see if they can raise that number," said Kim Forrest, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh.
She said an Amazon disclosure on the number of subscribers and their location "would be telling, to see how big of a phenomenon this is."
Among the stocks hurt by Amazon was Best Buy, which fell 6.3 percent to end at $54.23 in its largest daily percentage drop since late May 2016.
The decline was partly prompted by reports of an Amazon service launched earlier this year, similar to one from Best Buy, that helps customers set up a 'smart home' with Amazon's voice-controlled assistant Alexa, analysts said.