Also known as "Single's Day" for the repeated "1" in November 11, the event launched in 2009 by sector leader Alibaba has become a key date for Chinese manufacturers and retailers, accounting for a significant share of annual orders for many businesses.
This year's display of raw consumer power kicked off at midnight and by 10 AM (0730 IST) more than USD 16 billion in transactions had been processed by Alipay, Alibaba's online payment system.
The event has been adopted by Alibaba rivals such as JD.com, with merchants engaging in a cut-throat battle to slash prices and move goods.
Alibaba said that five minutes after midnight Alipay was processing 256,000 payment transactions per second, doubling last year's high-water mark.
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"At 12:07:23 AM, the number of payment transactions processed by Alipay surpassed 100 million, equivalent to the total number of payment transactions processed during 2012," Alibaba said.
More than half of China's 1.3 billion people are said to use smartphones and the devices have become central to daily life, used for messaging, shopping, news and entertainment, ordering taxis and meals, and serving as digital wallets for a range of point-of-sale purchases.
Double 11's transaction volume is pumped up by many Chinese holding off on purchases of everyday items like rice and toilet paper to take advantage of the price-slashing.
Alibaba seized on Double 11 as China's online answer to the late-November US "Black Friday" shopping rush.
It found a sweet spot combining China's burgeoning spending power, the Chinese love of a good bargain, and the growing national addiction to one-click smartphone payments.
Alibaba and JD stock have both doubled this year as revenues surged.
Alibaba is investing heavily in creating an entire user ecosystem encompassing cloud computing, artificial intelligence, and automated stores using face-recognition, and is pushing into overseas markets.
But environmentalists complain of ecological harm, accusing Alibaba and other e-commerce companies of fuelling a culture of excessive over-consumption and mountains of waste.