SHANGHAI  Wal-Mart and five other companies have agreed to invest $500 million in 360buy.com, a fast-growing online retailer in China, the Chinese company said.

Liu Qiangdong, the founder and chief executive 360buy, announced the investment of about 3.3 billion renminbi on his Chinese Twitter-style microblog last week. On Monday, a spokeswoman for 360buy, Li Jing, confirmed that Wal-Mart was one of the new investors that had pledged a combined $500 million to back the privately owned company, which is based in Beijing.

Ms. Li declined to divulge the value of the investment by Wal-Mart, the world’s leading retailer. She said a formal announcement with more details could be made within weeks.

Kevin Gardner, a spokesman for Wal-Mart, which is based in Bentonville, Ark., said in an e-mail Saturday that the retailer had made no announcement and did not comment on rumors or speculation.