By Jacqueline Corba

Amazon made company history in its biggest shopping holiday yet: during the fourth annual "Prime Day," the company lured more Prime members on a single day than ever before. So it's officialーPrime #FOMO is real.

Forrester Retail Analyst Sucharita Kodali said Amazon ー now valued at nearly $900 billion ー has a simple value proposition: "It's a good enough solution at a very attractive price," Kodali told Cheddar on Wednesday.

Amazon's discount day launched in 2015 and has since expanded to span 36 hours across 17 countries. In total, Prime members purchased 100 million products during the holiday this year.

Other retailers, eager to compete, are adopting the company's methods and creating their own shopping holidays.

Zulily, for example, will kick off its "Thrill Week" on July 23, featuring a scavenger hunt for consumers to find deals and steals.

"What we want to do is give them a 'Zulily on steroids' type experience, where every single day there's a treasure hunt on the site," Zulily Vice President of Brand Marketing Naama Bloom told Cheddar on Wednesday. "It's really about providing a fun, exciting, and entertaining shopping experience."

Even if Bloom isn't concerned, smaller companies may have cause to worry.

According to Adobe Analytics data, large retailers with more than $1 billion in annual revenue saw a 54 percent increase in sales, while smaller niche retailers saw an 18 percent decrease in sales on Prime Day.

"The challenge for a lot of these brands is that if consumers want the brand, consumers are often agnostic for where the transaction happens," said Forrester's Kodali. "More of them, I expect, are going to choose to just have their best products available only direct-to-consumer, because that's where the margins are the biggest."

"Ultimately the question for Amazon is, how do you provide enough value to the brands so that you don't scare them away."

For the full segment, click here.