Prime Day begins with a bang

Amazon's Prime Day isn't over yet, but the one-day sale is gathering steam and prompting other retailers to join in.

Macy's and Walmart are among the most aggressive, each launching deals and free shipping aimed to compete with Amazon's. But the vast majority of dollars spent on July 12, in total, will be on Amazon (NASDAQ:AMZN) in categories such as electronics and apparel, according to the NPD Group's Checkout Tracking.

Prime Day is a 24-hour shopping event that offers a constantly changing stream of deals, with a new one released every five minutes, for members of Amazon Prime.

Last year, Prime Day sales were higher than Black Friday for the online retailer and catapulted the event to the rank of fourth-busiest shopping day of the year after Thanksgiving, Cyber Monday and Black Friday. And according to Slice, Prime Day was the second-largest sales day for Amazon in 2015, with total Amazon sales (including both first-party and Marketplace sales) coming in 3.5 percent higher than Black Friday 2015.

Sales on Prime Day 2015 were four times higher than the average day during the rest of July 2015, reports Slice.

Amazon released a sneak peak several hours before the midnight start and has added more popular items like TVs and electronics based on customer feedback from last year. But early reports reveal some level of dissatisfaction with both the deals and a website glitch that kept shoppers from adding sales items to their carts.

The real goal of the day likely goes beyond realizing sales gains, and is in growing Prime membership. Amazon doesn't release numbers but it's estimated membership is close to 55 million, and Prime Day is designed to boost membership and get existing members to spend more.

For more:
- see this CBC News story
- see this (NSFW) Gizmodo story
- see this Washington Post story
- see this report by Slice

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