Japanese online shopping mall operator Rakuten Inc. was selling roughly US$575 million worth of shares in Ctrip.com, China's largest online travel agency, in a secondary stock offering, sources familiar with the deal said on Tuesday.

Rakuten was selling 13.29 million American depositary receipts (ADRs) in Nasdaq-listed Ctrip.com, or 20.11 percent of total shares outstanding, in a deal led by Morgan Stanley and co-managed by Citigroup. Pricing of the offering of existing shares is planned for Thursday.

Ctrip.com shares closed at US$43.28 on Monday.