Updated from 11:57 to include newer numbers from Alibaba and further commentary from an analyst.

Chinese e-commerce giant Alibaba (BABA) - Get Report is off to a very strong start on Singles Day, China's biggest shopping day of the year.

The e-commerce giant said that it had reached $1 billion in gross merchandise volume (GMV) just 8 minutes into Nov. 11 in China, $2 billion in 16 minutes, and passed $2.7 billion -- the total amount spent by U.S. shoppers on Cyber Monday last year -- after just 25 minutes. Alibaba passed $3 billion in sales in 30 minutes and hit $5 billion of GMV in 90 minutes.

The company expects the pace to continue at 120,000 orders at peak per second, up from 80,000 at peak per second in 2014.

"Early numbers from Alibaba indicate they will have another nice year of growth," Wedbush analyst Gil Luria said.

On top of the fast growth, Alibaba also said it was seeing the majority of the action coming from mobile, with 72% of the total GMV in the first 90 minutes happening on a mobile device. There were more than 27 million mobile buyers in the first hour.

"This year, Alibaba Group has transformed 11.11 into an unprecedented mobile shopping experience," said Daniel Zhang, chief executive officer of Alibaba Group.

Last year, $9.3 billion worth of orders were placed on Alibaba on Singles Day. And this year, Alibaba could surpass the $10 billion mark.

SunTrust analyst Bob Peck estimates that Alibaba will generate $12 billion in GMV this Singles Day.

What is today one of the largest sales events in the world first started out as an anti-Valentine's Day of sorts, created by a group of students at Nanjing University in the 1990s. The four 1s in 11/11 -- Singles Day takes place on Nov. 11 -- symbolize singles, so single people are encouraged to celebrate the day by buying things for themselves.

The day took off, and like any holiday, became a ripe opportunity for brands. In 2009, Alibaba took advantage of the day and helped turn it into a huge commercial event.

And Alibaba's not the only one that will benefit from the big day. JD.com (JD) - Get Report , a longtime rival of Alibaba, is also capitalizing on Singles Day this year with its own sales and promotions. While JD.com did not disclose how much GMV last year's Singles Day generated for the company, it did say that GMV more than doubled that of the previous year's Singles Day, and that the marketplace placed more than 14 million orders during the event, up 120% from 2013's Singles Day.

"No company can own a day," said Wedbush's Luria. "That's why JD should have a very successful day as well. As of last year it was very much an Alibaba event. I would expect starting this year for it to be a broader event than just Alibaba."