NEW YORK (AP) — The gravitational pull of Amazon Prime Day is so strong on shoppers it’s benefiting other retailers as well, according to an early analysis from a key data group.

On Monday, the first day of its 48-hour sales event, large retailers, those that generated annual revenue of at least a billion dollars, enjoyed a 64% increase in online sales compared with an average Monday, according to Adobe Analytics, which measures 80 of the top 100 retailers on the web in the U.S. That compares to last year’s 54%. In addition, niche retailers, those with annual revenue of less than $5 million, had a 30% increase in online sales.

Amazon’s fifth annual Prime Day, which this year began Monday afternoon, was created to drum up sales during sluggish summer months and sign up more users for the company’s membership program.

Other retailers have introduced sales to compete against Prime Day. Walmart has a “summer savings event” through Wednesday. Best Buy, eBay, Target and other retailers are also offering discounts.

The Seattle e-commerce behemoth said it was offering more than a million deals. Amazon’s own products, like its Fire tablets and Echo smart speakers, are usually among the strongest sellers.

The events have also helped to encourage shoppers to make back-to-school shopping purchases ahead of that season.

This year, some used the high-profile event as a way to garner attention for their protests against Amazon.

At a warehouse in Shakopee, Minnesota, Amazon workers staged a protest Monday to raise awareness of what they say are unfair working conditions. A group of tech workers in Seattle, called Amazon Employees for Climate Justice, is supporting the strike. Amazon said late last night that roughly 15 workers participated in the event outside of the Shakopee fulfillment center.

On Twitter, Massachusetts Senator and presidential candidate Elizabeth Warren voiced her support for the workers as well.

Amazon says it already offers what the workers are asking for.

“We provide great employment opportunities with excellent pay — ranging from $16.25-$20.80 an hour, and comprehensive benefits including health care, up to 20 weeks parental leave, paid education, promotional opportunities, and more,” spokeswoman Brenda Alfred said.

The company has faced labor unrest before in Shakopee and in Europe .

In New York, a coalition of labor groups planned to deliver 250,000 petitions to Amazon founder Jeff Bezos’ Manhattan home calling on the company to cut business ties with ICE and end abusive working conditions in its warehouses. And some on Twitter called for a blanket boycott of Amazon during Prime Day.

San Diego State University Marketing Professor Steven Osinski said the protests were unlikely to have an effect on sales, however.

“Americans liking discounts will trump worrying about higher wages for two days,” he said.

The company counts more than 100 million subscribers to its Prime loyalty program, which costs $119 a year and provides free two-day shipping, free streaming movies, TV shows, music and other perks.