Dive Brief:

• As retailers piggy-backed onto Amazon's Prime Day sales this year, U.S. e-commerce surpassed $11 billion ($5.6 billion on day one and $5.4 billion on day two), according to number-crunching from the Adobe Digital Economy Index. Amazon itself said it was the two biggest days ever for its small- and medium-sized marketplace sellers. 

• Total online spend across the industry for the two-day event — representing 6.1% growth over last year's $10.4 billion — also beat last year's $10.9 billion Cyber Monday, which is the biggest U.S. online shopping day by Adobe's measure. Amazon alone may have notched between $11 billion to $12 billion globally, up as much as 16% over last year, with U.S. sales of $8 billion to $8.5 billion, according to Telsey Advisory Group analysts.

• However, the e-commerce giant's average Prime Day order size fell to $44.75, from $54.64 in 2020 and $58.91 in 2019, according to Numerator research. Amazon didn't immediately return requests for details on total Prime Day sales or average order size.

Dive Insight:

It looks like Amazon took the bulk of Prime Day's revenue windfall, and the e-commerce giant added to its membership base.

Ten percent of those shopping at the retail giant during the sale joined Amazon Prime since the onset of the pandemic, with 2% of those joining for Prime Day this year in order to partake of the sale, which is limited to members, Numerator found.

But the early summer event had consumers shopping at other retailers of all sizes as well.

Revenue was up 29% at larger online retailers and 21% at smaller ones, according to a statement from Adobe Digital Insights Director Taylor Schreiner. Morgan Stanley researchers even expect to see brick-and-mortar store traffic improvements due to the sale, according to a June 24 client note. Retailers with BOPIS services enjoyed "a 10% boost in conversion compared to an average June day," while those without saw a conversion bump of just 3%, Adobe found.​ 

More than half of Prime Day shoppers stuck with Amazon, while a quarter browsed Walmart and 21% considered Target, according to Numerator. Otherwise, 10% considered club stores, 9% department stores, 8% Best Buy and 7% grocery stores, per that report.

​Several analysts said results from the two-day promotion benefited from the easing of pandemic-related restrictions, the pandemic's lingering boost to e-commerce, a strengthening economy and back-to-school shopping lists. And retailers didn't have to discount their merchandise all that much to make a sale, according to the Telsey team.

"Broadly, we believe retail promotions were flat to down relative to Prime Day 2020 — especially in apparel and select home products — likely reflecting strong current business trends, lean inventory, and expectations for a solid 2H21, particularly back-to-school and work," Telsey analysts led by Joseph Feldman said Wednesday. "In addition, we believe many retailers either strategically planned their promotions and/or pulled them forward."

Adobe similarly found diminished discounts, with pricing consistent throughout the sale. Toys and appliances were discounted the most, and televisions, sporting goods and electronics the least, per the firm's report. The sales momentum on the second day "despite relatively muted discounts across most categories, [suggests] that there's a pent up demand for online shopping as consumers look forward to a return to normalcy," Adobe's Schreiner said.​

Still, price-slashing was the name of the game, and not even luxury brands doing business through Amazon escaped that. Eight of the 35 brands on Amazon's Luxury Stores platform were tagged with "Summer Sale" prices during Prime Day, Wells Fargo analysts led by Ike Boruchow noted Wednesday.

"Amazon initially sold 'Luxury Stores' to brands indicating that their brand equity would be insulated from the low prices and discount frenzy on the separate platform, but it appears that the pressure to discount remains," Boruchow said.