The Chinese retailer Alibaba Group said on Monday that sales for its annual Singles’ Day shopping blitz have crossed the $30bn mark, putting the event on track to set a record in its 11th year.

The figure is equivalent to over 80% of US rival Amazon’s online store sales in the latest quarter and matches takings across Alibaba’s e-commerce platforms on Singles’ Day last year.

Sales growth for the full 24-hour event, however, is likely to fall short of the year earlier, analysts said, held back by a slowing overall e-commerce industry in China at a time when the country’s economic expansion is heading toward a historic low.

The event, a gauge of Chinese consumer sentiment, has also become a shop window this year for Alibaba as the firm plans to sell $15bn worth of shares in Hong Kong this month. The US-listed firm has spent big to diversify its business yet still earns over four-fifths of revenue from e-commerce.

Alibaba turned China’s informal Singles’ Day into a shopping event in 2009 and built it into the world’s biggest online sales fest, dwarfing Cyber Monday in the United States which took in $7.9bn last year. The name is a play on the date, 11 November, rendered 11/11 – or Double Eleven, as the event is also known.

The event has since been replicated at home and abroad, with Singles’ Day promotions found at rivals such as China’s JD.com and Pinduoduo Inc as well as South Korea’s 11thStreet and Singapore’s Qoo10.

But sales growth for Alibaba on Singles’ Day has weakened as China’s economy slowed. Last year, it posted a 27% year-on-year sales increase, the lowest in the event’s 10-year history. Citic Securities forecasts sales to rise 20-25% this year.

The Chinese retail juggernaut, with a market value of $486bn, kicked off this year’s 24-hour shopping bonanza with a live performance by pop star Taylor Swift followed by live-streamed marketing of over 1,000 brands.

Sales hit $1bn after one minute and eight seconds and reached 158.31bn yuan ($22.6bn) in the first nine hours, up 25% from the same point last year, Alibaba said. The firm also said 84 brands including those of Apple, L’Oreal and Fast Retailing’s Uniqlo each made over 100m yuan in sales in the first hour.

Over half of merchants on its Tmall marketplace used live streaming to sell products during the event, and sales generated through the medium surpassed 10bn yuan at 8.55am (0055GMT), Alibaba said.

Singles’ Day is known to be a stressful time for Alibaba employees with workers sleeping at the office to keep up with orders.

This year, at Alibaba’s campus in Hangzhou, workers bustled around in red T-shirts with the slogan “Make 11 happen.”

Percussion echoed through halls as departments banged large drums each time a sales record was broken. Pink rice cakes “dingshenggao”, or “victory cakes” eaten by Yue Army soldiers during the Song Dynasty – filled the office snack bars.

This was the first time Alibaba’s Singles’ Day is being held since its flamboyant co-founder Jack Ma resigned as chairman in September to “start a new life”.