Amazon reported quarterly revenue of $187.8 billion earlier this month, while Walmart reported its own earnings Thursday afternoon, posting a top line of $180.5 billion.

For what it’s worth, Walmart still leads Amazon in annual sales, but the e-commerce giant is expected to catch up there, too. FactSet projects Walmart will post $708.7 billion in revenue for the fiscal year, while Amazon may notch $700.8 billion.

Walmart has topped the Fortune 500 since 2013, where it has remained through today. LSEG senior analyst Tajinder Dhillon said Walmart has produced the highest quarterly revenues of any company since 2012, when it beat Exxon Mobil, CNBC reported. 

The Bentonville, Ark.–based retailer doesn’t get to boast every superlative. Amazon eclipsed Walmart as the largest retailer by market capitalization in July 2015 when its shares rose nearly 10% to give it a market value of $247.6 billion. At the time, Walmart’s was $230.5 billion. In the decade since, both companies have seen an astronomical rise in value: Amazon’s market cap is now $2.5 trillion; Walmart’s is north of $823 billion.

Amazon’s rise sends a clear signal to the competition.

“From the competitive point of view, it shows a nimble and responsive company,” Neil Saunders, managing director of GlobalData Retail, told Fortune.

At the same time, Amazon’s footprint wasn’t formed overnight. “It is a milestone, and it is significant,” Saunder said. “But it’s not like Amazon has gone from nothing to suddenly this position.”

Walmart, in its quiet period before earnings, declined Fortune’s request for comment. Amazon did not respond to a request for comment.

Amazon’s edge

Comparing the success of Amazon to Walmart’s is, in some ways, like comparing apples to oranges, Saunders said. While both companies have made their mark on retail, Amazon owes a chunk of its recent success to its cloud computing business AWS, which generated $90 billion in revenue in 2023. Its online advertising likewise boosted the company, jumping 19% year over year in the third quarter of 2024 to $14.3 billion.

Meanwhile, Walmart has continued its pivot on omnichannel strategy, balancing its brick-and-mortar business with e-commerce. It’s taken a “leaf out of Amazon’s playbook,” Saunders said, particularly in U.S. advertising, which grew 30% in the 12 months leading up to August 2024.

“This all-rounded approach—where retail is at the heart of the business, but other things generate revenue around it—is a model that’s been really successful, and it’s been an exemplar for other retailers to really copy Amazon in that strategy,” he said.

The copycatting goes both ways. Groceries from Walmart and subsidiary Sam’s Club make up 30% of the U.S.’s grocery sales, compared to Amazon’s 3%. After years of continuing to futz with its grocery strategy, Amazon has made some significant strategic and leadership moves. Last August, it launched a subscription model for Prime and Prime Access members to get an annual unlimited grocery delivery subscription for orders over $35 at Whole Foods, Amazon Fresh, and select other stores. And earlier this month, Amazon announced Whole Foods Market CEO Jason Buechel would now lead its worldwide grocery stores unit, while maintaining his current CEO role and reporting to worldwide Amazon stores CEO Doug Herrington.

Amazon may have passed Walmart for now, but it’s a victory with an inevitable expiration date, according to Saunders. A new retailer will likely master the formula for success and unseat Amazon in a matter of decades, something Amazon founder and executive chairman Jeff Bezos has admitted to.

“Amazon is not too big to fail,” Bezos reportedly said in a November 2018 all-hands meeting. “In fact, I predict one day Amazon will fail. Amazon will go bankrupt. If you look at large companies, their life spans tend to be 30-plus years, not a hundred-plus years.”