As shoppers gear up for Amazon Prime Day beginning Monday evening, the biggest sales day of the year for the company, Jack Ma is probably snickering somewhere.

That’s because his Alibaba has its own Prime Day — and it’s exponentially bigger.

November 11 is known as Singles Day in China and it has become a major shopping holiday for the e-commerce giant. Singles Day began as an anti-Valentine’s Day founded by college students in the 1990s, according to the Communist Party-owned People’s Daily.

Last year, Alibaba racked up almost $18 billion in sales during the 24-hour event.

To be fair, Prime Day is only in its infancy, while Alibaba’s bonanza has been around since 2009, when the company began using the “holiday” to promote sales during the usually slow period before the Lunar New Year season.

Prime Day began on July 15, 2015, to commemorate the Seattle, Washington-based company’s 20th birthday. Its inaugural event was a success, exceeding Amazon’s Black Friday sales, while the second edition last year was declared “the biggest day ever for Amazon” in a press release.

Amazon’s stock was up almost 2 percent in trading Monday. Prime Day officially kicks off Monday night at 9 pm ET and has been expanded by six hours this year to 30 hours.

One key difference between the two events is that Prime Day is open only to Amazon Prime subscribers, while Alibaba’s is open to all shoppers. Amazon’s event in many ways serves as a recruiting tool for new Prime members, by far its most valuable customers.

“The other piece of this is the attraction to become a Prime member,” said Kerry Rice, a senior analyst at Needham & Company. “Certainly revenue is important. But there’s a lot of data points out there that Prime members spend more than non-Prime, are retained longer.”

It’s difficult to say exactly how Prime Day affects the company’s bottom line because the company does not release figures from it. However, retail firm FBIC predicted the company could generate $525 million in sales last year.

Jeff Bezos‘ behemoth did release some numbers about the day, including a more than 50 percent increase in orders from the United States from 2015 and a record day for Fire TV, Fire tablets, Kindles and Alexa-enabled devices. In addition, more than 1 million customers used the Amazon app for the first time on last year’s Prime Day.

Rice said Amazon might have learned from Alibaba’s Singles Day success, but still has some catching up to do to reach Alibaba’s spectacle.

“Alibaba’s is a little bit more progressed,” he said. “They have celebrities; there’s a whole online kickoff. They’ve made it a pretty big affair. Amazon has not quite gone to that length.”

Indeed, some of Alibaba’s figures from Singles Day are eye-popping. The company ran up $17.8 billion in sales, roughly the same as the entire country of Spain’s e-commerce sales in 2016, according to eMarketer’s research.

More items were bought on Alibaba’s platform in that 24 hours than the entire combined Black Friday and Cyber Monday sales in the United States.

Cyber Monday saw sales top $3.4 billion in the United States last year, or less than one-fifth of Alibaba’s sales from Singles Day.

$1 billion worth of orders were placed in the first five minutes of Alibaba’s event.

Amazon’s total revenue last year was $136 billion, meaning Alibaba’s single day of sales would account for more than 10 percent of Amazon’s total annual revenue — and that includes the vast array of Amazon’s ecosystem.

The goals for the companies remain the same, however: to generate sales.