Wang Jianlin, chairman of Dalian Wanda Commercial Properties, attends a ceremony during the debut of the company at the Hong Kong Stock Exchange Dec 23, 2014. [Photo/Agencies]

China's Dalian Wanda Group Co, whose real estate arm just raised about $3.7 billion in a Hong Kong share sale, announces to invest in a Chinese third-party payment platform to step into the nation's O2O market, sources familiar with the deal said.

According to the source, the deal made by the China's biggest commercial real estate developer, with 99Bill Corp, a Chinese payment processor similar to PayPal, reaches to more than $300 million.

The Beijing-based property conglomerate is diversifying into e-commerce as it seeks to maintain profitability during China's property downturn.

The company's WeChat account has posted a statement to confirm the deal while there isn't any sepcific trading volume has been mentioned in the news release.

Dalian Wanda's investment is expected to be valued at more than 2 billion yuan ($322.55 million), the source said.

The 99Bill tie-up will put property billionaire Wang Jianlin, Dalian Wanda's chairman, into direct competition with Alibaba Group Holding Ltd Executive Chairman Jack Ma and his Alipay unit, which controls about 80 percent of China's mobile payment market.

Alipay settled $788 billion in transactions in the year ended on June 30.

Wang has said he was preparing to shift the focus of the conglomerate towards entertainment, tourism and online businesses. He said at a conference this month that he would announce plans for transforming the group early next year.

In August, Dalian Wanda teamed up with two Chinese Internet giants, Tencent Holdings Ltd and Baidu Inc, to launch an e-commerce joint venture that could leverage the group's 104 Wanda Plaza shopping malls, 72 luxury hotels and 150 movie theaters in 111 Chinese cities.

Dalian Wanda is investing 5 billion yuan and holds a 70 percent stake in the venture, which is promoting the use of e-vouchers, e-coupons and e-tickets at the group's properties.

"O2O (online to offline) is the biggest pie in e-commerce," said Wang. "This is just the beginning."

Wang Jianlin ranks 3rd on Asia's rich list, trailing Li Ka-shing and Jack Ma

A poor performance by Dalian Wanda Commercial Properties shares on their Hong Kong debut is expected to merely dent the personal wealth of Wang Jianlin, chairman of holding company Dalian Wanda Group.

His ranking as the second-richest man on the Chinese mainland is widely thought to have remained unchallenged.

However, the unexpected shares setback has put him further behind Jack Ma of Alibaba on the rich list.