China's securities regulator said on Friday it was concerned by the huge valuation gap between domestic and overseas stocks and speculation on shares in shell companies, potentially bad news for firms looking to go home to cash in on rich valuations.

Dalian Wanda Commercial Properties, owned by China's richest man Wang Jianlin, had been looking to delist from the Hong Kong bourse just 15 months after its debut, unhappy with its share performance and preferring to place its bets on an upcoming Shanghai listing.

It was not immediately clear if a final decision had been taken by Wanda Group to drop the take-private plan, the sources told Reuters. One of the issues is an agreement already signed by Wanda Group with prospective investors to raise $4 billion for the buyout and they have already paid part of that sum upfront.

Wanda Commercial did not immediately respond to a request for comment.

(Reporting by Clare Jim; Editing by Lisa Jucca)