(This November 11 story corrects to say "above", not "below", in 6th paragraph)

By Josh Horwitz

HANGZHOU, China (Reuters) - Chinese retailer Alibaba Group Holding Ltd's sales for its 24-hour Singles' Day shopping blitz hit a record $38.4 billion, more than U.S. rival Amazon.com Inc's haul last quarter from online store sales.

But sales growth for the annual shopping festival eased to 26%, the weakest since the event started in 2009, held back by a slowing e-commerce industry in China as the country's economic expansion heads toward a historic low.

The event https://tmsnrt.rs/2WTFm7V, a gauge of Chinese consumer sentiment, has also become a shop window this year for Alibaba as it plans to sell $15 billion worth of shares in Hong Kong this month. The U.S.-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 $7.9 billion last year. The name is a play on the date, Nov. 11, 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 Inc and Pinduoduo Inc as well as South Korea's 11thStreet and Singapore's Qoo10.

Alibaba said on Monday its gross merchandise volume or GMV for the whole event came in at 268.4 billion yuan ($38.4 billion), up 26% from last year and above Citic Securities' forecasts for a 20-25% expansion.

In 2018, it posted a 27% sales increase.

CELEBRITY START

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

The firm said 84 brands including those of Apple Inc, L'Oreal SA and Fast Retailing Co Ltd's Uniqlo each made over 100 million 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 10 billion yuan at 8.55 a.m. (0055 GMT), Alibaba said.

"Nearly all our brands have opted for livestreaming promotions some time this year," says Josh Gardner, who helps overseas companies sell products on Tmall as CEO of Kung Fu Data.

"It's more entertaining than browsing through a product detail page. Traffic from livestreaming is easy to convert into transactions, and Tmall has supported stores that run livestreaming activities with resources."

One vendor, New Zealand-based nutritional supplement maker Clinicians, broadcast livestreams from a booth set up on Alibaba's campus. According to Carlos Zhao, China market manager, the company has seen a 40% jump in sales after it started livestreaming in China six months ago.

"This is a product form from new Zealand, everything is in English, and so many people are selling similar products, so customers wonder, 'Which one do I choose from?'" he told Reuters. "Having a livestreamer can help to break those barriers."

Tmall has said it expects over 500 million users to make purchases this year, about 100 million more than last year. It has also put more emphasis this year on promotions targeting areas outside of China's massive first- and second-tier cities.

"The younger generation is buying more, and the customer from rural areas, the customers from lower-tier cities, they are buying imported products," Tmall General Manager Alvin Liu told reporters.

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 bustle around in red t-shirts with the slogan 'Make 11 happen'.

Percussion echoes through halls as departments bang large drums each time a sales record is broken. Pink rice cakes – dingshenggao, or 'victory cakes' eaten by Yue Army soldiers during the Song Dynasty - fill the office snack bars.

This is 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".

(Reporting by Josh Horwitz in Hangzhou; Additional reporting by Brenda Goh in Shanghai and Cheng Leng in Beijing; Editing by Christopher Cushing, Emelia Sithole-Matarise and Himani Sarkar)