HONG KONG (Reuters/IFR) - Chinese online group discounter Pinduoduo Inc PDD.O priced its U.S. initial public offering (IPO) at $19 per American depositary share (ADS), raising $1.63 billion in the second-biggest U.S. float by a Chinese firm this year, according to three people familiar with the situation.

The pricing values money-losing Pinduoduo - which counts Chinese internet giant Tencent Holdings Ltd 0700.HK as a main backer - at $23.8 billion including all outstanding share options, compared with a valuation of $15 billion following a funding round in April.

The fast-growing company allows consumers to group together to get better discounts from merchants selling goods as varied as clothes, kitchenware and gadgets. It offered about 85.6 million ADS or about 6.8 percent of its enlarged share capital, at $16 to $19 each.

Pinduoduo declined to comment on the pricing. The people declined to be named because they were not authorised to speak to the media.

Pinduoduo is the latest Chinese tech firm tapping international capital markets to bolster coffers amid ever-intensifying competition with domestic rivals, notably e-commerce heavyweights Alibaba Group Holding Ltd BABA.N and JD.com Inc JD.O.

It is also joining several sizable Chinese listings in New York this year even as Sino-U.S. trade tensions involving tit-for-tat tariffs rattle global markets.

Chinese video streaming service provider iQiyi Inc IQ.O raised $2.42 billion from a Nasdaq IPO in March, and Tencent Music Entertainment, China's largest music-streaming firm, aims to raise up to 4 billion in a U.S. IPO planned for October.

Set up by former Google engineer Colin Huang in 2015, Pinduoduo will begin trading on Nasdaq under the symbol PDD on Thursday.

It said in U.S. regulatory filings that it had attracted over 300 million active buyers and more than 1 million merchants to its platform.

Due to low-priced products and a large user base in China’s smaller cities, the firm’s gross merchandise volume exceeded 100 billion yuan ($14.98 billion) last year. Alibaba’s Taobao marketplace took five years to reach that milestone, while JD.com took 10 years.

Investors and analysts also attribute its rapid growth to the online traffic derived from Tencent’s messaging-to-shopping app WeChat, which helps direct many of its more than 1 billion users to Pinduoduo.

“We believe WeChat accounts for the majority of buyer traffic, and Pinduoduo could not have built up its large user base cost-effectively and rapidly without WeChat,” wrote Arun George, a technology analyst who publishes on independent research platform Smartkarma.

Pinduoduo’s revenue has grown sharply, reaching 1.38 billion yuan in January-March from 37 million yuan in the same period a year prior. Its net loss, however, remained broadly steady at 201 million yuan.

China Renaissance, CICC, Credit Suisse and Goldman Sachs are advising Pinduoduo.